Method for estimating the amount of carbon dioxide absorbed by carbon dioxide-absorbing sludge fine powder

Abstract

[Problem] To provide a method for estimating the carbon dioxide absorption amount of a carbon dioxide-absorbed sludge fine powder. [Solution] The carbon dioxide absorption amount is estimated in relation to a carbon dioxide-absorbed sludge fine powder obtained by carbon dioxide being absorbed into a sludge fine powder recovered from unused concrete. A method for estimating the carbon dioxide absorption amount according to the present invention uses an estimation index comprising either the specific surface area or the ignition loss. Additionally, in relation to the carbon dioxide-absorbed sludge fine powder which is subject to estimation, an estimation index is measured for the sludge fine powder before carbon dioxide absorption to obtain a pre-absorption measurement value, and an estimation index is measured for the carbon dioxide-absorbed sludge fine powder to obtain a post-absorption measurement value. The carbon dioxide absorption amount is estimated from the pre-absorption measurement value and the post-absorption measurement value.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a carbon dioxide-absorbing sludge fine powder obtained by absorbing carbon dioxide into sludge fine powder recovered from unused concrete composed of residual concrete or returned concrete, and to a method for estimating the amount of carbon dioxide absorbed.

Background Art

[0002] Concrete, mortar, etc. placed at a construction site or the like are manufactured at a ready-mix concrete plant and transported by a truck agitator. Concrete that has not been used at the construction site or that has failed in the acceptance inspection is returned to the plant as so-called residual concrete or returned concrete. It has been reported that such so-called unused concrete reaches 2 to 3% of the total concrete. Conventionally, these have been treated as industrial waste, but as the treatment cost becomes high and it also leads to an environmental load, effective utilization of unused concrete has been demanded.

[0003] In recent years, in order to prevent global warming, reduction of carbon dioxide emissions has been required in various fields of industry. Looking at the cement manufacturing industry, which accounts for about 4% of the total carbon dioxide emissions in Japan, the carbon dioxide emissions from cement manufactured by high-temperature firing are large, reaching about 766 kg / ton in terms of the unit consumption. In order to suppress the carbon dioxide emissions, establishment of technologies such as reducing the amount of cement used or substituting a part of the cement with a binder made of other low-carbon materials is expected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Patent Document 1 describes a method for recovering sludge fine powder with a high proportion of unhydrated cement from unused concrete such as residual concrete and returned concrete. Specifically, water is added to unused concrete to make a slurry, gravel and sand are removed from this slurry, and then fine sand is removed using a wet cyclone to obtain sludge water. Next, the sludge water is dewatered to obtain a dewatered cake, and this dewatered cake is placed in a rotating drum and crushed and dried simultaneously while supplying high-temperature air. Since crushing and drying are performed simultaneously, the progress of the hydration reaction is suppressed, and high-quality sludge fine powder with a high proportion of unhydrated cement is obtained. Sludge fine powder can be used as a binder that can replace part of the cement, as proposed in Patent Document 2, for example. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The sludge powder described in Patent Document 1 can be obtained from unused concrete that would otherwise be waste, and it consumes little fuel during crushing and drying. Therefore, replacing part of the cement with sludge powder in a water-curable hardened body is advantageous because it can reduce carbon dioxide emissions. In other words, sludge powder can be said to be a binder for low-carbon materials. The inventors produced carbon dioxide-absorbing sludge powder by exposing such sludge powder to high concentrations of carbon dioxide for absorption. They then conducted experiments to obtain a water-curable hardened body using carbon dioxide-absorbing sludge powder as a binder. The experiments revealed that when carbon dioxide-absorbing sludge powder is used as a binder, the fluidity is improved compared to when sludge powder that has not absorbed carbon dioxide is used as a binder, and the strength is substantially the same. In other words, it was found that carbon dioxide-absorbing sludge powder reduces carbon dioxide emissions substantially more than sludge powder, can be used as a binder, and has excellent workability.

[0007] Incidentally, it has been found that the degree of improvement in the fluidity of carbon dioxide-absorbing sludge powder compared to sludge powder varies depending on the amount of carbon dioxide absorbed. Therefore, the amount of carbon dioxide absorbed is an important indicator for controlling the quality of carbon dioxide-absorbing sludge powder. The amount of carbon dioxide absorbed in carbon dioxide-absorbing sludge powder can be measured, for example, by differential thermogravimetric analysis. That is, the carbon dioxide-absorbing sludge powder is heated so that its temperature gradually rises, and its mass is measured each time. Since carbon dioxide is separated within a specific temperature range, the amount of carbon dioxide absorbed can be determined by assuming that the mass decrease within this temperature range is the mass of carbon dioxide. However, measuring by differential thermogravimetric analysis requires specialized analytical equipment and is time-consuming. Therefore, it is difficult to adopt this method in the manufacturing site of carbon dioxide-absorbing sludge powder. This is because it is cumbersome as it would have to be measured every time carbon dioxide-absorbing sludge powder is manufactured. There are other methods for evaluating the amount of carbon dioxide absorbed in carbon dioxide-absorbing sludge powder, such as the coulometer method which measures the dissolved inorganic carbon concentration, but for similar reasons, all of these are difficult to adopt in the manufacturing site.

[0008] The present invention aims to provide a method for estimating the amount of carbon dioxide absorbed by carbon dioxide-absorbing sludge fine powder, which is an important indicator for controlling its quality. [Means for solving the problem]

[0009] The present invention relates to carbon dioxide-absorbing sludge powder obtained by absorbing carbon dioxide into sludge powder recovered from unused concrete consisting of residual concrete or returned concrete, and is configured as a method for estimating the amount of carbon dioxide absorbed. The sludge powder is manufactured by a slurrying step of adding water to unused concrete to make a slurry, a separation step of separating and removing gravel and sand from the slurry to obtain sludge water, a fine sand removal step of separating and removing fine sand from the sludge water using a wet cyclone to obtain concentrated sludge water, a dewatering step of dewatering the concentrated sludge water to obtain a sludge cake, and a crushing and drying step of placing the sludge cake in a rotating drum and supplying hot air to crush and dry it to obtain sludge powder. Carbon dioxide-absorbing sludge powder is obtained by absorbing carbon dioxide into such sludge powder. The carbon dioxide absorption estimation method of the present invention uses an estimation index consisting of either specific surface area or loss on ignition. Then, regarding the carbon dioxide-absorbing sludge fine powder to be estimated, the estimation index is measured on the sludge fine powder before carbon dioxide absorption to obtain the pre-absorption measurement value, and the estimation index is measured on the carbon dioxide-absorbing sludge fine powder to obtain the post-absorption measurement value. From these pre-absorption measurement value and post-absorption measurement value... Based on a predetermined linear function determined in advance during the preparation stage. It is configured to estimate the amount of carbon dioxide absorbed. The preparation stage involves obtaining pre-absorption and post-absorption measurements for multiple sludge fine powders produced from multiple different unused concretes, as well as carbon dioxide-absorbing sludge fine powders that have absorbed carbon dioxide. The amount of carbon dioxide absorbed is then measured to obtain actual carbon dioxide values. A linear function, which is the correlation between the change in the estimated index and the amount of carbon dioxide absorbed, is then determined from the actual carbon dioxide values, pre-absorption measurements, and post-absorption measurements. [Effects of the Invention]

[0010] This invention makes it possible to easily estimate the amount of carbon dioxide absorbed by carbon dioxide-absorbing sludge fine powder. [Brief explanation of the drawing]

[0011] [Figure 1] This is a flowchart showing the method for producing carbon dioxide absorbing sludge fine powder according to the first embodiment of this implementation. [Figure 2] This graph shows the changes in temperature and mass when differential thermogravimetric analysis is performed on carbon dioxide absorption sludge fine powder. [Figure 3]This graph shows the relationship between carbon dioxide absorption amount and specific surface area for several carbon dioxide-absorbing sludge fine powders. [Figure 4] This graph shows the relationship between the change in the specific surface area of ​​carbon dioxide-absorbing sludge powder relative to the specific surface area of ​​sludge powder, and the amount of carbon dioxide absorbed by the carbon dioxide-absorbing sludge powder. [Figure 5] This graph shows the relationship between carbon dioxide absorption and ignition loss for several carbon dioxide-absorbing sludge fine powders. [Figure 6] This graph shows the relationship between the change in ignition loss of carbon dioxide absorbing sludge powder and the amount of carbon dioxide absorbed by the carbon dioxide absorbing sludge powder, compared to the ignition loss of sludge powder. [Modes for carrying out the invention]

[0012] This embodiment will now be described. The present invention is a method for estimating the amount of carbon dioxide absorbed by carbon dioxide absorbing sludge fine powder. In other words, it is a method for estimating the amount of carbon dioxide contained in carbon dioxide absorbing sludge fine powder. First, the carbon dioxide absorbing sludge fine powder according to this embodiment will be described.

[0013] <Carbon dioxide absorbing sludge fine powder> Concrete is manufactured by mixing Portland cement, aggregates such as gravel and sand, water, and admixtures using a forced-mix mixer. The concrete manufactured in this way is transported to the construction site and poured, but some may remain unused or fail acceptance inspections. Such concrete is returned to the ready-mix concrete plant or sent to other processing facilities as leftover concrete or returned concrete. In other words, it is unused concrete. The carbon dioxide absorbing sludge fine powder according to this embodiment is manufactured by processing such unused concrete.

[0014] In the method for manufacturing carbon dioxide-absorbing sludge fine powder, first, as shown in FIG. 1, a slurrying step S1 is carried out. That is, water is added to unused concrete to make it into a slurry. This enables the cement component to dissolve sufficiently in the water added. The slurry may contain washing wastewater obtained by washing the mixer of a truck agitator and washing wastewater in a ready-mix concrete plant.

[0015] Next, an aggregate separation step S2 is carried out. This is a step of removing solid components such as aggregates from the slurry obtained in the slurrying step S1. It is carried out by a plurality of vibrating sieves with different mesh sizes, and the slurry is sequentially processed to separate aggregates such as gravel and sand. The recovered aggregates will be reused. The undersize remaining after the aggregates are separated is sludge water containing a large amount of cement component.

[0016] Next to the aggregate separation step S2, a fine sand removal step S3 is carried out. In this embodiment, this step is carried out by a wet cyclone to remove fine sand, that is, fine sand components, from the sludge water. That is, concentrated sludge water is obtained. The concentrated sludge water obtained by this step is processed in the next dehydration step S4. However, when the cement component contained in the concentrated sludge water is thin, it may be sent back to the slurrying step S1 and reused as water for slurrying other unused concrete. By doing so, the sludge water will have the cement component concentrated.

[0017] A dehydration step S4 is performed on the concentrated sludge water. That is, the concentrated sludge water is treated by a filter press to obtain a sludge cake. At this time, supernatant water is also obtained, which can be reused as the mixing water for concrete. Next, a crushing and drying step S5 is performed on the sludge cake. Any device can be used as long as it can crush and dry the sludge cake while it is operating. However, in this embodiment, a predetermined rotating drum that can efficiently perform crushing and drying is used. The rotating drum is provided with crushing and stirring blades that rotate at high speed inside, and hot air is supplied. The sludge cake is put into the rotating drum, rotated, and hot air is supplied. Then, the sludge cake is crushed by the crushing and stirring blades and dried by the hot air to obtain sludge fine powder.

[0018] For the sludge fine powder thus obtained, a carbon dioxide absorption step S6 is performed. In the carbon dioxide absorption step S6, the sludge fine powder is placed in a container equipped with stirring means, high-concentration carbon dioxide is supplied into the container, and the temperature inside the container is raised to 50°C or higher. When the sludge fine powder is exposed to carbon dioxide while being stirred for a predetermined time, for example, 30 minutes or more, or 1 hour or more, the sludge fine powder absorbs carbon dioxide. That is, carbon dioxide-absorbed sludge fine powder is obtained.

[0019] <Carbon Dioxide Absorption Amount Estimation Method According to the First Embodiment> The inventors of the present invention investigated various physical property changes in sludge fine powders of various qualities and carbon dioxide-absorbed sludge fine powders obtained by absorbing carbon dioxide into them, and found that there is a correlation between a predetermined physical property change and the amount of carbon dioxide absorption. As the physical property in which the correlation was found, the inventors selected the specific surface area and established a carbon dioxide absorption estimation method according to the first embodiment. The carbon dioxide absorption estimation method according to the first embodiment estimates the amount of carbon dioxide absorption (CA) absorbed in the carbon dioxide-absorbed sludge fine powder from the specific surface area (SS) of the sludge fine powder and the specific surface area (CS) of the carbon dioxide-absorbed sludge fine powder. It can be expressed by the following formula 1 using the function f(). CA = f(SS, CS) (Formula 1) However, the amount of carbon dioxide absorbed (CA) shall be treated as the percentage of the weight of carbon dioxide relative to the weight of the sludge fine powder. Since the specific surface area is an indicator for estimating the amount of carbon dioxide absorbed, it can be considered an estimation indicator.

[0020] <Preparation Stage> To investigate the correlation between the change in specific surface area, an estimated indicator, and the amount of carbon dioxide absorbed, the following experiment was conducted. Experimental method: Six types of unused concrete, A, B, C, D, E, and F, with different time intervals since mixing, were used as experimental subjects. Steps S1 to S5 of the carbon dioxide absorbing sludge powder manufacturing method according to this embodiment, shown in Figure 1, were performed on these unused concretes A-F to obtain sludge powders A0, B0, C0, D0, E0, and F0 that had not absorbed carbon dioxide. These sludge powders A0-F0 were each placed in experimental containers, and the carbon dioxide concentration in the containers was adjusted to 80% by volume relative to air, and the temperature inside the containers was set to 50°C to allow carbon dioxide absorption. For sludge powders A0-C0, carbon dioxide absorbing sludge powders with absorption times of 1 hour, 3 hours, and 24 hours were obtained. The sludge powders with an absorption time of 1 hour were designated carbon dioxide absorbing sludge powders A1, B1, and C1; those with 3 hours were designated carbon dioxide absorbing sludge powders A3, B3, and C3; and those with 24 hours were designated carbon dioxide absorbing sludge powders A24, B24, and C24. In other words, the designation will be a combination of an English letter (A-F) indicating the type of unused concrete and a number (0-24) indicating the carbon dioxide absorption time. On the other hand, for sludge powders D-F, carbon dioxide absorbing sludge powders with carbon dioxide absorption times of 3 hours, 6 hours, 12 hours, 18 hours, and 24 hours were obtained. These were similarly designated as D3-F24. The amount of carbon dioxide absorbed and the specific surface area were measured for sludge powders A0-F0 and carbon dioxide absorbing sludge powders A1-F24. These are summarized in Table 1.

[0021] [Table 1]

[0022] The amount of carbon dioxide absorbed (%) was measured by differential thermogravimetric analysis. Figure 2 shows a graph of the change in mass loss (%) with respect to temperature (°C) when differential thermogravimetric analysis was performed on sludge powder D0 produced from unused concrete D and carbon dioxide absorbing sludge powders D3 to D24. Here, the mass loss in the temperature range of 600°C to 800°C was judged to be the mass of carbon dioxide and was considered to be the amount of carbon dioxide absorbed by the carbon dioxide absorbing sludge powder. The specific surface area was measured according to the method specified in JIS R5201, that is, measured using a Blaine permeation apparatus.

[0023] <Example of a carbon dioxide absorption estimation method according to the first embodiment> Equation 1, shown above, indicates that the amount of carbon dioxide absorbed (CA) is given by a function f() that takes the specific surface area (SS) of the sludge powder and the specific surface area (CS) of the carbon dioxide absorbing sludge powder as arguments. However, the specific function f() has not been explained. As an example of a function f() that realizes Equation 1, supervised learning type machine learning can be used. The specific surface areas of sludge powders A0 to F0 and the specific surface areas of carbon dioxide absorbing sludge powders A1 to F24 are used as input data, and the carbon dioxide absorption amounts corresponding to each carbon dioxide absorbing sludge powder A1 to F24 are used as training data to train the neural network. Then, the trained neural network realizes the function f() and, when the specific surface areas of an unknown sludge powder and a carbon dioxide absorbing sludge powder are input, it outputs the amount of carbon dioxide absorbed. In other words, the amount of carbon dioxide absorbed can be estimated.

[0024] <Analysis of correlations> The inventors obtained the graphs shown in Figure 3 from the results in Table 1. The sludge powder A0, carbon dioxide absorbing sludge powders A1, A3, and A24 obtained from unused concrete A were combined into a single graph, and similarly, the sludge powder B0, carbon dioxide absorbing sludge powders B1, B3, and B24 obtained from unused concrete B were combined into a single graph, and so on, to obtain graphs for the A series through the F series. From the graphs in Figure 3, it could be seen that for each series (A to F), the specific surface area decreased linearly as the amount of carbon dioxide absorbed increased, and that the slope of the graphs was generally the same.

[0025] <Linear function equation for realizing the carbon dioxide absorption estimation method according to the first embodiment> Therefore, the inventors made the function f() in Equation 1 a linear function and created the following Equation 2. CA=a1(CS-SS)+a2 (Formula 2) However, CA: Carbon dioxide absorption (%) CS: Specific surface area of ​​carbon dioxide absorbing sludge fine powder SS: Specific surface area of ​​sludge fine powder a1, a2: constants For the experimental data in Table 1, the change in specific surface area, i.e., the difference between the specific surface area CS of the carbon dioxide-absorbing sludge powder and the specific surface area SS of the sludge powder, was plotted on the x-axis, and the amount of carbon dioxide absorbed CA was plotted on the y-axis to obtain the graph in Figure 4. The constants a1 and a2 in Equation 2 were determined by the least squares method, and Equation 3 was obtained. CA=-0.002(CS-SS) (Formula 3) However, CA: Carbon dioxide absorption (%) CS: Specific surface area of ​​carbon dioxide absorbing sludge fine powder SS: Specific surface area of ​​sludge fine powder By inputting the specific surface areas of the unknown sludge powder and the carbon dioxide-absorbing sludge powder into Equation 3, the amount of carbon dioxide absorbed can be obtained. In other words, the amount of carbon dioxide absorbed can be estimated.

[0026] <Modified example of the carbon dioxide absorption estimation method according to the first embodiment> Although the carbon dioxide absorption estimation method according to the first embodiment can be realized by Equation 3, the function f() in Equation 1 may be realized by other mathematical formulas. For example, it can be constructed from a quadratic equation, a higher-order equation of degree cubic or higher, a polynomial, an exponential function, etc. In any case, since the specific surface area of ​​carbon dioxide absorbing sludge fine powders A1, A3, ... F24 decreases as the amount of carbon dioxide absorbed increases, the structure and form of the mathematical formula are not limited as long as it expresses this relationship.

[0027] <Method for estimating carbon dioxide absorption amount according to the second embodiment> As explained, the inventors investigated various physical property changes in sludge fine powders of different qualities and carbon dioxide-absorbing sludge fine powders obtained by absorbing carbon dioxide from them. In this investigation, it was found that, in addition to specific surface area, ignition loss also correlates with the amount of carbon dioxide absorbed. Therefore, the inventors selected ignition loss as an indicator and established a carbon dioxide absorption estimation method according to the second embodiment. The carbon dioxide absorption estimation method according to the second embodiment estimates the amount of carbon dioxide absorbed by the carbon dioxide-absorbing sludge fine powder (CA) from the ignition loss of the sludge fine powder (SW) and the ignition loss of the carbon dioxide-absorbing sludge fine powder (CW). This can be expressed by the function g() in the following equation 4. CA = g(SW, CW) (Equation 4) However, the amount of carbon dioxide absorbed (CA) shall be treated as the percentage of the weight of carbon dioxide relative to the weight of the sludge fine powder. Since the loss on ignition is an indicator for estimating the amount of carbon dioxide absorbed, this can also be considered an estimation indicator.

[0028] <Preparation Stage> The experiments described above yielded sludge powders A0-F0 and carbon dioxide-absorbing sludge powders A1-F24 for unused concrete A-F. These were heated at 950±25°C until constant weight was reached, and the mass loss was measured. In other words, the loss on ignition was measured. This is summarized in Table 2.

[0029] [Table 2]

[0030] <Example of a carbon dioxide absorption estimation method according to the second embodiment> As a specific function g() that realizes equation 4 shown above, supervised learning type machine learning can be used, similar to the first embodiment. The ignition loss of sludge powders A0 to F0 and the ignition loss of carbon dioxide absorbing sludge powders A1 to F24 are used as input data, and the carbon dioxide absorption amount corresponding to each carbon dioxide absorbing sludge powder A1 to F24 is used as training data to train the neural network. Then, the trained neural network realizes the function g() and, when the ignition loss of an unknown sludge powder and the respective carbon dioxide absorbing sludge powders are input, it outputs the carbon dioxide absorption amount. In other words, it is possible to estimate the amount of carbon dioxide absorbed.

[0031] <Analysis of correlations> The inventors obtained the graph shown in Figure 5 from the results in Table 2. The sludge powder A0, carbon dioxide absorbing sludge powders A1, A3, and A24 obtained from unused concrete A were combined into a single graph, and similarly, the sludge powder B0, carbon dioxide absorbing sludge powders B1, B3, and B24 obtained from unused concrete B were combined into a single graph, and so on, to obtain graphs for the A series through the F series. From the graph in Figure 5, it could be seen that for each series (A to F), the ignition loss increased linearly as the amount of carbon dioxide absorbed increased, and that the slope of the graphs was generally the same.

[0032] <Linear function equation for realizing the carbon dioxide absorption estimation method according to the second embodiment> Therefore, the inventors made the function g() in Equation 4 a linear function and created the following Equation 5. CA = b1(CW - SW) + b2 (Equation 5) However, CA: Carbon dioxide absorption (%) CW: Loss on ignition of carbon dioxide-absorbing sludge fine powder SW: Loss on ignition of sludge powder b1, b2: constants For the experimental data in Table 2, the change in ignition loss, i.e., the difference between the ignition loss CW and ignition loss SW of the carbon dioxide-absorbing sludge powder, was plotted on the x-axis, and the amount of carbon dioxide absorbed CA was plotted on the y-axis to obtain the graph in Figure 6. The constants b1 and b2 in Equation 5 were determined by the least squares method, and Equation 6 was obtained. CA=0.6594(CW-SW)-0.5618 (Formula 6) However, CA: Carbon dioxide absorption (%) CW: Loss on ignition of carbon dioxide-absorbing sludge fine powder SW: Loss on ignition of sludge powder By inputting the ignition loss of the unknown sludge powder and the carbon dioxide-absorbing sludge powder into Equation 6, the amount of carbon dioxide absorbed can be obtained. In other words, the amount of carbon dioxide absorbed can be estimated.

[0033] <Modified example of the carbon dioxide absorption estimation method according to the second embodiment> Although the carbon dioxide absorption estimation method according to the second embodiment can be realized by Equation 6, the function g() in Equation 4 may be realized by other mathematical formulas. For example, it can be constructed from a quadratic equation, a cubic or higher degree equation, a polynomial, an exponential function, etc. In any case, since the ignition loss of carbon dioxide absorbing sludge fine powders A1, A3, ... F24 increases as the amount of carbon dioxide absorbed increases, the structure and form of the mathematical formula are not limited as long as it expresses this relationship.

Claims

[Claim 1] A method for estimating the amount of carbon dioxide absorbed by carbon dioxide-absorbing sludge powder obtained by absorbing carbon dioxide into sludge powder recovered from unused concrete consisting of residual concrete or returned concrete, The sludge fine powder is produced by a slurrying process in which water is added to the unused concrete to make a slurry, A separation step to separate and remove gravel and sand from the slurry to obtain sludge water, A step to remove fine sand particles from the sludge water using a wet cyclone to obtain concentrated sludge water, A dehydration step to obtain a sludge cake by dehydrating the concentrated sludge water, The product is manufactured through a crushing and drying process, in which the sludge cake is placed in a rotating drum, hot air is supplied to crush and dry it, and fine sludge powder is obtained. The carbon dioxide absorption estimation method uses an estimation index consisting of either specific surface area or loss on ignition to obtain a pre-absorption measurement value for the carbon dioxide absorbing sludge fine powder to be estimated by measuring the estimation index for the sludge fine powder before carbon dioxide absorption, and obtains a post-absorption measurement value by measuring the estimation index for the carbon dioxide absorbing sludge fine powder, and estimates the amount of carbon dioxide absorbed from the pre-absorption measurement value and the post-absorption measurement value based on a predetermined linear function determined in the preparation step. The preparation step involves obtaining pre-absorption and post-absorption measurements for each of the multiple sludge fine powders produced from multiple different unused concretes and the carbon dioxide-absorbing sludge fine powders that have absorbed carbon dioxide, and measuring the amount of carbon dioxide absorbed to obtain an actual carbon dioxide value. The method for estimating carbon dioxide absorption involves determining the linear function, which is the correlation between the change in the estimation index and the amount of carbon dioxide absorbed, from the actual carbon dioxide value, the pre-absorption measurement, and the post-absorption measurement.

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