Co2 recovery apparatus, co2 recovery method, and control program

Abstract

To provide a CO2 recovery apparatus, a CO2 recovery method, and a control program capable of efficiently recovering CO2 without increasing energy consumption.SOLUTION: A CO2 recovery apparatus according to the present disclosure that alternately repeats CO2 adsorption by an adsorption unit and CO2 desorption by a recovery unit, comprises: a measurement unit that measures an adsorption amount of CO2 by the adsorption unit and a desorption amount of CO2 by the recovery unit; and a control unit that controls the desorption amount of CO2 by the recovery unit so that, when CO2 adsorption by the adsorption unit and CO2 desorption by the recovery unit are alternately repeated for three or more cycles, an average of residual ratios of CO2 adsorbed in CO2 adsorbents in at least the first to third cycles falls within a range of 40.9% to 80.6%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a CO2 recovery device, a CO2 recovery method, and a control program. [Background technology]

[0002] Development of CO2 recovery devices that recover CO2 (carbon dioxide) from the atmosphere is underway. For example, Patent Document 1 discloses a flue gas decarbonation system that determines the flow rate of carbon dioxide in flue gas from the flow rate of the flue gas and the carbon dioxide concentration in the flue gas, adjusts the ratio of the flow rate of a regenerated amine adsorption solution supplied to a carbon dioxide adsorption tower to the carbon dioxide flow rate to a constant value, and adjusts the ratio of the flow rate of steam from a heater to the flow rate of the amine adsorption solution to a constant value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3212524 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the equipment disclosed in Patent Document 1 had a problem in that if the desorption temperature set when desorbing CO2 from the adsorption solution that has adsorbed CO2 was increased in order to improve the CO2 recovery efficiency, energy consumption would increase.

[0005] The present disclosure has been made in consideration of the above background, and aims to provide a CO2 recovery device, a CO2 recovery method, and a control program that are capable of recovering CO2 efficiently without increasing energy consumption. [Means for solving the problem]

[0006] The CO2 recovery device according to the present disclosure has a CO2 adsorbent composed of a CO2 adsorbent containing an amino group and multiple porous carriers supporting the CO2 adsorbent, and includes an adsorption unit that adsorbs CO2 contained in gas supplied from the outside onto the CO2 adsorbent, and a capture unit that adjusts the temperature of the adsorption unit to a higher temperature than when CO2 was adsorbed, thereby desorbing and recovering the CO2 adsorbed on the CO2 adsorbent from the CO2 adsorbent. The CO2 recovery device alternately repeats the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit, and further includes a measurement unit that measures the amount of CO2 adsorbed by the adsorption unit and the amount of CO2 desorbed by the capture unit, and a control unit that controls the amount of CO2 desorbed by the capture unit so that the average residual rate of CO2 adsorbed on the CO2 adsorbent in at least the first to third cycles is within the range of 40.9% to 80.6% when the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit are alternately repeated three or more cycles. This CO2 capture device can capture CO2 efficiently without raising the desorption temperature more than necessary. In other words, this CO2 capture device can capture CO2 efficiently without increasing the energy consumption caused by the desorption temperature.

[0007] The CO2 residual rate is the ratio of the amount of CO2 adsorbed in the CO2 adsorbent after the CO2 is desorbed by the capture unit to the amount of CO2 adsorbed in the CO2 adsorbent before the CO2 is desorbed by the capture unit.

[0008] The CO2 adsorption conditions by the adsorption section in each cycle may be set to the same conditions, and the CO2 desorption conditions by the capture section in each cycle may be set to the same conditions.

[0009] The adsorption of CO2 by the adsorption section and the desorption of CO2 by the capture section may be alternately repeated five or more cycles.

[0010] The recovery unit may further be configured to desorb and recover the CO2 adsorbed in the CO2 adsorbent by adjusting the adsorption unit to a pressure lower than that during CO2 adsorption.

[0011] The recovery unit may further be configured to adjust the humidity of the adsorption unit to a higher humidity than when CO2 is adsorbed, thereby desorbing and recovering the CO2 adsorbed in the CO2 adsorbent from the CO2 adsorbent.

[0012] The plurality of porous supports may be applied to a substrate having a honeycomb shape and having a plurality of pores with an average pore diameter of 2 nm to 200 nm.

[0013] The plurality of porous supports may have a plurality of pores with an average pore diameter of 2 nm to 200 nm and may be in the form of pellets.

[0014] The plurality of porous supports may be composed mainly of either silica or alumina.

[0015] The CO2 adsorbent may be a polyamine containing any of polyethyleneimine, methylated polyethyleneimine, isopropylated polyethyleneimine, polyallylamine, pentaethylenehexamine, methylated pentaethylenehexamine, isopropylated pentaethylenehexamine, tetraethylenepentamine, methylated tetraethylenepentamine, and isopropylated tetraethylenepentamine, or an amino group-containing compound containing the polyamine.

[0016] The present disclosure provides a CO2 capture method using a CO2 capture device comprising a CO2 adsorbent composed of an amino-containing CO2 adsorbent and multiple porous supports supporting the CO2 adsorbent. The CO2 adsorbent comprises an adsorption section that adsorbs CO2 contained in a gas supplied from an external source onto the CO2 adsorbent, and a capture section that controls the adsorption section to a temperature higher than that during CO2 adsorption, thereby desorbing and capturing the CO2 adsorbed on the CO2 adsorbent. The method alternates between adsorption by the adsorption section and desorption by the capture section. The method controls the amount of CO2 desorbed by the capture section so that the average residual CO2 adsorbed on the CO2 adsorbent in at least the first, second, and third cycles is between 40.9% and 80.6%. This CO2 capture method achieves efficient CO2 capture without excessively high desorption temperatures. In other words, this CO2 capture method can capture CO2 efficiently without increasing the energy consumption caused by the desorption temperature.

[0017] The control program according to the present disclosure provides a CO2 recovery device including: an adsorption unit having a CO2 adsorbent constituted by a CO2 adsorbent containing an amino group and a plurality of porous carriers supporting the CO2 adsorbent, and causing CO2 contained in a gas supplied from the outside to be adsorbed onto the CO2 adsorbent; and a capture unit adjusting the adsorption unit to a temperature higher than that during CO2 adsorption, thereby desorbing and recovering the CO2 adsorbed onto the CO2 adsorbent, and alternately repeating the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit; The control program causes a computer to execute a CO2 capture process using a CO2 adsorbent. The control program causes the computer to execute the following steps: measuring the amount of CO2 adsorbed by the adsorption unit and the amount of CO2 desorbed by the capture unit; and controlling the amount of CO2 desorbed by the capture unit so that the average residual rate of CO2 adsorbed in the CO2 adsorbent in at least the first to third cycles is within the range of 40.9% to 80.6% when the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit are alternately repeated for three or more cycles. This control program can efficiently capture CO2 without unnecessarily increasing the desorption temperature. In other words, this control program can efficiently capture CO2 without increasing the energy consumption due to the desorption temperature. [Effects of the Invention]

[0018] The present disclosure makes it possible to provide a CO2 recovery device, a CO2 recovery method, and a control program that are capable of recovering CO2 efficiently without increasing energy consumption. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram showing a configuration example of a CO2 recovery device according to a first embodiment. [Figure 2] 3 is a flowchart showing the operation of the CO2 recovery apparatus according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing test results of the CO2 desorption rate in only one cycle of CO2 capture processing using the CO2 capture device according to the first embodiment. [Figure 4] 10 is a diagram showing test results of the CO2 adsorption amount and the CO2 desorption amount in each cycle of a plurality of cycles of CO2 capture processing by the CO2 capture device according to the first embodiment. FIG. [Figure 5] 2 is a diagram showing an example of the molecular structure of a CO2 adsorbent used in the CO2 adsorbent of the CO2 recovery device according to the first embodiment. FIG. [Figure 6] FIG. 10 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the first test. [Figure 7] FIG. 10 is a graph showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the first test. [Figure 8] FIG. 10 is a diagram showing the CO2 residual rate in each cycle of a CO2 capture process in multiple cycles, among the results of the first test. [Figure 9] FIG. 10 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the second test. [Figure 10] FIG. 10 is a diagram showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the second test. [Figure 11] FIG. 10 is a diagram showing the CO2 residual rate in each cycle of a multiple-cycle CO2 capture process, among the results of the second test. [Figure 12] FIG. 10 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the third test. [Figure 13] FIG. 10 is a graph showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the third test. [Figure 14] FIG. 10 is a diagram showing the CO2 residual rate in each cycle of a multiple-cycle CO2 capture process, among the results of the third test. [Figure 15] FIG. 10 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a multiple-cycle CO2 recovery process, among the results of the fourth test. [Figure 16]FIG. 10 is a diagram showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the fourth test. [Figure 17] FIG. 10 is a diagram showing the residual CO2 rate in each cycle of a multi-cycle CO2 capture process, among the results of the fourth test. [Figure 18] FIG. 10 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the seventh test. [Figure 19] FIG. 10 is a diagram showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the seventh test. [Figure 20] FIG. 10 is a diagram showing the CO2 residual rate in each cycle of a multi-cycle CO2 capture process, among the seventh test results. [Figure 21] FIG. 13 is a diagram showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the eighth test. [Figure 22] FIG. 10 is a graph showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the eighth test. [Figure 23] FIG. 13 is a diagram showing the CO2 residual rate in each cycle of a multiple-cycle CO2 capture process, among the results of the eighth test. [Figure 24] FIG. 1 is a diagram summarizing the results of several tests. [Figure 25] This figure shows the relationship between the ratio d / b of the amount of CO2 desorption in the 10th cycle to the amount of CO2 desorption in the 1st cycle and the ratio d / a of the amount of CO2 desorption in the 10th cycle to the amount of CO2 adsorption in the 1st cycle for multiple test results. [Figure 26] This figure shows the relationship between the average value c of the CO2 residual rate after the CO2 desorption process from the first to third cycles for multiple test results and the ratio d / b of the CO2 desorption amount in the 10th cycle to the CO2 desorption amount in the first cycle. [Figure 27] This figure shows the relationship between the average CO2 residual rate c after the CO2 desorption process from the first to third cycles for multiple test results and the ratio d / a of the CO2 desorption amount in the 10th cycle to the CO2 adsorption amount in the first cycle. [Figure 28] FIG. 10 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of a CO2 recovery process over multiple cycles, among the results of the 10th test. [Figure 29] FIG. 10 is a graph showing the change in total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the 10th test. [Figure 30] FIG. 10 is a diagram showing the CO2 residual rate in each cycle of a multiple-cycle CO2 capture process, among the results of the 10th test. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential means for solving the problems. For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0021] <First Embodiment> FIG. 1 is a block diagram showing a configuration example of a CO2 recovery device 1 according to a first embodiment. The CO2 recovery device 1 is a device that recovers CO2 by alternately repeating a CO2 adsorption process and a CO2 desorption process. Specifically, the CO2 recovery device 1 includes a CO2 adsorption unit 11, a CO2 recovery unit 12, a measurement unit 13, and a control unit 14.

[0022] The CO2 adsorption unit 11 adsorbs CO2 (carbon dioxide) contained in gas (exhaust gas or air) supplied from the outside into the CO2 adsorbent 111. The gas from which some of the CO2 has been captured by the CO2 adsorbent 111 is discharged to the outside of the CO2 recovery device 1.

[0023] The CO2 adsorbent 111 is composed of a CO2 adsorbent containing an amino group and a plurality of porous carriers supporting the CO2 adsorbent. The porous carrier is mainly composed of either silica or alumina and has a plurality of pores with an average pore diameter of 2 nm to 200 nm. For example, the porous carrier is applied to a substrate having a honeycomb shape. Alternatively, the porous carrier has a pellet shape.

[0024] The CO2 adsorbent is a polyamine containing any of polyethyleneimine, methylated polyethyleneimine, isopropylated polyethyleneimine, polyallylamine, pentaethylenehexamine, methylated pentaethylenehexamine, isopropylated pentaethylenehexamine, tetraethylenepentamine, methylated tetraethylenepentamine, and isopropylated tetraethylenepentamine, or an amino group-containing compound containing a polyamine.

[0025] The CO2 capture unit 12 desorbs and captures the CO2 adsorbed in the CO2 adsorbent 111 by adjusting the CO2 adsorption unit 11 (more specifically, the storage space for the CO2 adsorbent 111 provided in the CO2 adsorption unit 11) to a temperature higher than that during CO2 adsorption. Note that the CO2 capture unit 12 may desorb and capture the CO2 adsorbed in the CO2 adsorbent 111 by adjusting the CO2 adsorption unit 11 to a temperature higher than that during CO2 adsorption, or by adjusting the pressure of the CO2 adsorption unit 11 to a lower pressure or by circulating a gas such as water vapor to a lower CO2 partial pressure. For this reason, the CO2 capture unit 12 may include, for example, a temperature adjustment unit that adjusts the temperature of the CO2 adsorption unit 11, a pressure adjustment unit that adjusts the pressure of the CO2 adsorption unit 11, a humidity adjustment unit that adjusts the humidity of the CO2 adsorption unit 11, and the like.

[0026] The measuring unit 13 measures the amount of CO2 adsorbed by the CO2 adsorption unit 11 and the amount of CO2 desorbed by the CO2 capture unit 12. The measuring unit 13 also calculates the residual CO2 amount and CO2 residual rate, which will be described later, from the CO2 adsorption amount and CO2 desorption amount.

[0027] First, the measurement unit 13 measures the amount of CO2 adsorbed by the CO2 adsorbent 111 at the end of the CO2 adsorption process by the CO2 adsorption unit 11, based on the amount of CO2 remaining P adsorbed (residing) in the CO2 adsorbent 111 before the start of the CO2 adsorption process by the CO2 adsorption unit 11 and the amount of CO2 adsorbed Q adsorbed by the CO2 adsorbent 111 from the start of the CO2 adsorption process by the CO2 adsorption unit 11 to the end of the CO2 adsorption process. The amount of CO2 adsorption Q is calculated from the difference between the amount of CO2 contained in the gas before the CO2 capture process that is supplied from the outside to the CO2 adsorption unit 11 and the amount of CO2 contained in the gas after the CO2 capture process that is discharged from the CO2 adsorption unit 11 to the outside.

[0028] Thereafter, the measurement unit 13 measures the residual amount of CO2 T (=RS) remaining in the CO2 adsorbent 111 from the adsorbed amount of CO2 R adsorbed in the CO2 adsorbent 111 at the end of the CO2 adsorption process by the CO2 adsorption unit 11 and the desorbed amount of CO2 S desorbed from the CO2 adsorbent 111 by the CO2 desorption process by the CO2 capture unit 12. The measurement unit 13 then calculates a CO2 residual ratio T / R, which is the ratio of the residual CO2 amount T remaining in the CO2 adsorbent 111 after the CO2 desorption process by the CO2 capture unit 12 to the adsorbed amount of CO2 R adsorbed in the CO2 adsorbent 111 at the end of the CO2 adsorption process by the CO2 adsorption unit 11.

[0029] The control unit 14 controls the alternating repetition of the CO2 adsorption process by the CO2 adsorption unit 11 and the CO2 desorption process by the CO2 capture unit 12. The control unit 14 also sets the processing conditions (conditions such as temperature, pressure, and humidity) for the CO2 adsorption process and the CO2 desorption process.

[0030] Furthermore, the control unit 14 moves to the next cycle of CO2 capture processing in a state in which a portion of the CO2 adsorbed in the CO2 adsorbent 111 remains without being captured in the CO2 capture processing in any cycle.

[0031] Specifically, in the CO2 recovery process from the first cycle to the third cycle, the control unit 14 controls the amount of CO2 desorbed S by the CO2 recovery unit 12 so that the average of the residual rate T / R of CO2 adsorbed on the CO2 adsorbent 111 falls within the range of 40.9% to 80.6%. The derivation of the specific value of the CO2 residual rate T / R will be described later.

[0032] Thereby, when the CO2 recovery device 1 proceeds to the CO2 recovery process of the next cycle after recovering all the CO2 adsorbed on the CO2 adsorption unit 11 in the CO2 recovery process of a certain cycle, in the CO2 recovery process of the next cycle, a sufficiently high proportion of CO2 can be desorbed from the CO2 adsorbent 111 and recovered under low temperature conditions. That is, the CO2 recovery device 1 can efficiently recover CO2 without increasing the energy consumption caused by the desorption temperature.

[0033] <Operation of CO2 Recovery Device 1> Subsequently, the operation of the CO2 recovery device 1 will be described using FIG. 2. FIG. 2 is a flowchart showing the operation of the CO2 recovery device 1.

[0034] First, the CO2 recovery device 1 performs the CO2 recovery process of the first cycle. In the CO2 recovery process of the first cycle, the CO2 recovery device 1 starts the adsorption process of the CO2 contained in the gas supplied from the outside to the accommodation space of the CO2 adsorbent 111 (step S101). Specifically, the CO2 recovery device 1 adsorbs the CO2 contained in the gas supplied from the outside to the accommodation space of the CO2 adsorbent 111 onto the CO2 adsorbent 111. The gas from which a part of the CO2 has been recovered by the CO2 adsorbent 111 is discharged to the outside of the CO2 recovery device 1.

[0035] After a predetermined adsorption treatment time of, for example, about 5 minutes has elapsed, the CO2 recovery device 1 ends the CO2 adsorption treatment (step S102). At this time, the CO2 recovery device 1 adds the residual amount P of CO2 adsorbed (remaining) in the CO2 adsorbent 111 before the start of the CO2 adsorption treatment to the adsorbed amount Q of CO2 adsorbed in the CO2 adsorbent 111 from the start of the CO2 adsorption treatment to the end of the CO2 adsorption treatment, thereby calculating the adsorbed amount R of CO2 adsorbed in the CO2 adsorbent 111 at the end of the CO2 adsorption treatment (i.e., the adsorbed amount R of CO2 adsorbed in the CO2 adsorbent 111 immediately before the CO2 desorption treatment).

[0036] After the CO2 adsorption process is completed, the CO2 recovery device 1 then performs a CO2 desorption process. Specifically, the CO2 recovery device 1 first performs evacuation of the accommodation space of the CO2 adsorbent 111, oxygen purging, heating, and the like (step S103). As a result, in the CO2 desorption process, the accommodation space of the CO2 adsorbent 111 is adjusted to a higher temperature than in the CO2 adsorption process. Also, in the CO2 desorption process, the accommodation space of the CO2 adsorbent 111 may be adjusted to a lower pressure than in the CO2 adsorption process, or may be adjusted to a lower CO2 partial pressure by circulating a gas such as water vapor. As a result, the CO2 adsorbed by the CO2 adsorbent 111 begins to desorb (step S104).

[0037] Here, the CO2 recovery device 1 calculates the CO2 residual ratio T / R, which is the ratio of the CO2 residual amount T remaining in the CO2 adsorbent 111 after the CO2 desorption process to the CO2 adsorption amount R adsorbed in the CO2 adsorbent 111 at the end of the CO2 adsorption process (step S105).

[0038] The CO2 recovery device 1 then controls the desorption process so that the average value of the CO2 residual ratio T / R from at least the first to third cycles is within a range of the predetermined ratio α or less (and the predetermined ratio β or more) (step S106). Note that the CO2 recovery device 1 may control not only the desorption process but also the adsorption process so that the average value of the CO2 residual ratio T / R from at least the first to third cycles is within a range of the predetermined ratio α or less (and the predetermined ratio β or more). Thereafter, the CO2 recovery device 1 ends the CO2 desorption process and cools the storage space of the CO2 adsorbent 111 to lower the temperature (step S107). The predetermined ratios α and β satisfy the condition α>β and each exhibit a value within a range of 40.9% to 80.6%.

[0039] Thereafter, if the CO2 recovery process is to be continued (YES in step S108), the CO2 recovery device 1 performs a second cycle of CO2 recovery process (steps S101 to S108). Note that the residual CO2 amount P adsorbed (residing) in the CO2 adsorbent 111 before the start of the second cycle of CO2 adsorption process indicates the residual CO2 amount T remaining in the CO2 adsorbent 111 after the first cycle of CO2 desorption process. If the CO2 recovery process is not to be continued (NO in step S108), the CO2 recovery device 1 ends the CO2 recovery process.

[0040] As a result, the CO2 recovery device 1 can desorb and recover a sufficiently high proportion of CO2 from the CO2 adsorbent 111 under low temperature conditions in the CO2 recovery process of the next cycle, compared to when all of the CO2 adsorbed in the CO2 adsorption unit 11 is recovered in a CO2 recovery process of one cycle before moving on to the CO2 recovery process of the next cycle. In other words, the CO2 recovery device 1 can efficiently recover CO2 without increasing energy consumption due to the desorption temperature.

[0041] FIG. 3 shows test results for the CO2 desorption rate in a single cycle of CO2 capture using the CO2 capture device 1. In the example of FIG. 3, the horizontal axis represents desorption process time, and the vertical axis represents the CO2 desorption rate. In the test shown in FIG. 3, polyethyleneimine (PEI) was used as the amine-based CO2 adsorbent. In the CO2 desorption process, the pressure was reduced to 3 kPa, steam was supplied to reduce the CO2 partial pressure, and the temperature was set to 100°C, 90°C, or 80°C. In the test shown in FIG. 3, the amount of CO2 adsorbed by the CO2 adsorbent 111 before the start of the CO2 capture process (before the start of the CO2 adsorption process) was very small. Therefore, this CO2 capture process can be considered to be the same as the CO2 capture process in the previous cycle, when the CO2 retention rate T / R was very low.

[0042] As shown in Figure 3, when a desorption process is performed for 600 seconds after the adsorption process, the CO2 desorption rate is approximately 70% when the set temperature is 100°C, but when the set temperature is 80°C, it is approximately 30%, less than half of the rate when the set temperature is 100°C. In other words, generally, to increase the CO2 capture efficiency, it is necessary to increase the temperature during the desorption process, which increases energy consumption.

[0043] FIG. 4 is a diagram showing test results of the CO2 adsorption amount and CO2 desorption amount for each cycle in a multiple-cycle CO2 capture process using the CO2 capture device 1. In the example of FIG. 4, the horizontal axis represents the number of cycles of the CO2 capture process, and the vertical axis represents the CO2 adsorption amount and CO2 desorption amount. In the test of FIG. 4, polyethyleneimine was used as the amine-based CO2 adsorbent. In addition, in the CO2 adsorption process, simulated air with a volumetric flow rate SV of 2.4E+5 / h was circulated through the CO2 adsorbent 111 for 5 minutes with the temperature set to 30°C, thereby adsorbing CO2 into the CO2 adsorbent 111. Thereafter, a CO2 desorption process was performed for 5 minutes with the temperature set to 80°C.

[0044] As shown in Fig. 4, the amount of CO2 desorbed in the first cycle is small, but the amount of CO2 desorbed increases with the increase in the number of cycles. The amount of CO2 desorbed after the fifth cycle has increased by more than twice compared to the amount of CO2 desorbed in the first cycle. From this, it can be seen that the CO2 recovery device 1 transfers to the CO2 recovery process of the next cycle in a state where a part of the CO2 adsorbed on the CO2 adsorbent is left without being recovered in the CO2 recovery process of any cycle. As a result, in the next cycle, a sufficiently high proportion of CO2 can be desorbed and recovered from the CO2 adsorption unit 11 under low-temperature conditions. That is, the CO2 recovery device 1 can efficiently recover CO2 without increasing the consumption energy.

[0045] <Test Contents and Test Results of CO2 Recovery Process> Subsequently, the test contents and test results of the CO2 recovery process will be described. From these test results, the CO2 residual rate for each cycle suitable for the CO2 recovery device 1 has been derived.

[0046] <Test Specimens Used in the Test> In the test of the CO2 recovery process, two types of test specimens are used as the CO2 adsorbent 111.

[0047] The first test specimen used as the CO2 adsorbent 111 is a porous carrier obtained by coating 50 g / L of silica gel on the surface of a cordierite substrate in the shape of a four-cornered hole honeycomb with a cell diameter of 8 mm × thickness of 50 mm, a cell density of 400 cells per square inch, and a wall thickness of 4.5 mils, and loading polyethyleneimine (branched Mw = 600) so that the amine weight / (amine weight + silica gel weight) = 0.35.

[0048] The second test material used as the CO2 adsorbent 111 is formed by coating the surface of a four-hole honeycomb cordierite substrate with cells of 8 mm diameter x 50 mm thickness, a cell density of 400 cells / square inch, and a wall thickness of 4.5 mils with 50 g / L of silica gel, and by supporting isopropylated polyethyleneimine on the substrate so that the amine weight / (amine weight + silica gel weight) = 0.35.

[0049] Fig. 5 shows the molecular structures of the CO2 adsorbents supported on two types of test materials (CO2 adsorbents 111) used in the CO2 capture test. The upper part of Fig. 5 shows the molecular structure of polyethyleneimine (PEI), and the lower part of Fig. 5 shows the molecular structure of isopropyl polyethyleneimine (IP-PEI).

[0050] <Test conditions> In the CO2 capture process test, CO2 adsorption and CO2 desorption processes are repeated alternately.

[0051] First, in the CO2 adsorption process, either dry adsorption or humidified adsorption is performed.

[0052] In the dry adsorption process, a model gas with a volumetric flow rate (SV) of 2.39E+5 / h is passed through one of the above-mentioned test materials (CO adsorbent 111) for five minutes at a temperature of 30°C, allowing CO adsorption into the test material. The model gas used here is a dry gas prepared by adding 400 ppm of CO to pure nitrogen gas. The CO adsorption amount is calculated based on the difference between the CO concentration (400 ppm) of the model gas supplied to the honeycomb (CO adsorbent 111) and the CO concentration of the model gas that passed through the honeycomb, as well as the gas flow rate. A HORIBA MEXA-1700D CO meter is used to measure the CO concentration, but other methods are possible.

[0053] In the humidified adsorption process, a model gas with a volumetric flow rate (SV) of 2.39E+5 / h is passed through one of the above-mentioned test materials (CO adsorbent 111) for five minutes at a temperature of 30°C, allowing CO adsorption into the test material. The model gas used here is pure nitrogen gas to which 400 ppm of CO was added, humidified to a relative humidity of 60% to 70%. The CO adsorption amount is calculated based on the difference between the CO concentration (400 ppm) of the model gas supplied to the honeycomb (CO adsorbent 111) and the CO concentration of the model gas that passed through the honeycomb, as well as the gas flow rate. A HORIBA MEXA-1700D CO meter was used to measure the CO concentration, but other methods are possible.

[0054] Next, in the CO2 desorption process, either dry desorption or reduced pressure steam desorption is performed.

[0055] In the dry desorption process, pure nitrogen gas is passed through the test material (CO2 adsorbent 111) heated to a predetermined temperature in a thermostatic chamber at a volumetric flow rate SV of 4.77E+4 / h for 5 minutes to desorb the CO2 adsorbed on the test material. The amount of CO2 desorption is calculated based on the gas flow rate and the CO2 concentration contained in the pure nitrogen gas that passed through the honeycomb (CO2 adsorbent 111). The CO2 concentration is measured using a HORIBA MEXA-1700D CO2 meter, but is not limited to this.

[0056] In the reduced pressure steam desorption process, the test material (CO2 adsorbent 111) is heated to a predetermined temperature in a thermostatic chamber and depressurized to 3 kPa. Steam is passed through the test material at a rate of 0.013 g / min by weight for 5 minutes, thereby desorbing the CO2 adsorbed on the test material. The amount of CO2 desorption is calculated based on the flow rate of the diluted gas obtained by combining the steam that has passed through the honeycomb with nitrogen gas at a flow rate of 2 L / min, and the CO2 concentration contained in the diluted gas. The CO2 concentration is measured using a HORIBA MEXA-1700D CO2 meter, but is not limited to this.

[0057] In addition, a saturated adsorption test is conducted as an additional test. The test conditions for saturated adsorption are the same as those for CO2 adsorption, except for the model gas supply time. In the saturated adsorption test, the model gas is supplied continuously until the CO2 concentration of the model gas passing through the honeycomb stops changing, and then the apparent saturated adsorption amount of CO2 is measured.

[0058] <First Test Results (Example 1)> The results of the first test of the CO2 capture process are explained below. In the first test, the first test material containing polyethyleneimine was used, and 10 cycles of humidified adsorption treatment and reduced pressure steam desorption treatment at a temperature set at 80°C were repeated alternately.

[0059] FIG. 6 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the first test. FIG. 7 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the first test. Note that FIG. 7 also shows the saturated CO2 adsorption amount. FIG. 8 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the first test. Note that FIG. 8 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p, in addition to the CO2 residual rate. The results of the first test are also shown in FIG. 24, which is a diagram summarizing the results of the first to ninth tests.

[0060] In the first test results, the CO2 adsorption amount a in the first cycle was 0.0407 g per 1 g of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0176 g per 1 g of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 56.2%. The CO2 retention rates from the second cycle onwards are shown in Figure 8. The CO2 desorption amount d in the tenth cycle was 0.0350 g per 1 g of CO2 adsorbent. The change rates d / b=2.01 and d / a=0.87.

[0061] <Second Test Results (Example 2)> The results of the second test of the CO2 capture process are explained below. In the second test, a second test material containing isopropyl polyethyleneimine was used, and 10 cycles of humidified adsorption and reduced pressure steam desorption at a temperature of 60°C were repeated alternately.

[0062] FIG. 9 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the second test. FIG. 10 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the second test. Note that FIG. 10 also shows the saturated CO2 adsorption amount. FIG. 11 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the second test. Note that FIG. 11 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p, in addition to the CO2 residual rate. The results of the second test are also shown in FIG. 24, which summarizes the results of the first to ninth tests.

[0063] In the second test results, the CO2 adsorption amount a in the first cycle was 0.0277 g per gram of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0118 g per gram of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 56.4%. The CO2 retention rates from the second cycle onwards are shown in Figure 11. The CO2 desorption amount d in the tenth cycle was 0.0240 g per gram of CO2 adsorbent. The change rates d / b=2.03 and d / a=0.87.

[0064] <Third Test Results (Example 3)> The results of the third test of the CO2 capture process are explained below. In the third test, the first test material containing polyethyleneimine was used, and dry adsorption treatment and dry desorption treatment at a temperature set at 80°C were alternately repeated 10 times.

[0065] FIG. 12 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the third test. FIG. 13 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the third test. FIG. 14 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the third test. In addition to the CO2 residual rate, FIG. 14 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p. The results of the third test are also shown in FIG. 24, which summarizes the results of the first to ninth tests.

[0066] In the third test results, the CO2 adsorption amount a in the first cycle was 0.0314 g per 1 g of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0120 g per 1 g of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 64.8%. The CO2 retention rates from the second cycle onwards are shown in Figure 14. The CO2 desorption amount d in the tenth cycle was 0.0216 g per 1 g of CO2 adsorbent. The change rates d / b=1.80 and d / a=0.69.

[0067] <Fourth Test Results (Example 4)> The results of the fourth test of the CO2 capture process are explained below. In the fourth test, the first test material containing polyethyleneimine was used, and 10 cycles of humidified adsorption treatment and reduced pressure steam desorption treatment at a temperature set to 70°C were repeated alternately.

[0068] FIG. 15 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the fourth test. FIG. 16 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the fourth test. Note that FIG. 16 also shows the saturated CO2 adsorption amount. FIG. 17 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the fourth test. Note that FIG. 17 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p, in addition to the CO2 residual rate. The results of the fourth test are also shown in FIG. 24, which summarizes the results of the first to ninth tests.

[0069] In the fourth test results, the CO2 adsorption amount a in the first cycle was 0.0447 g per 1 g of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0149 g per 1 g of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 73.9%. The CO2 retention rates from the second cycle onwards are as shown in Figure 17. The CO2 desorption amount d in the tenth cycle was 0.0267 g per 1 g of CO2 adsorbent. The change rates d / b=1.79 and d / a=0.60.

[0070] <Fifth Test Results (Example 5)> The results of the fifth test of the CO2 capture process are explained below. In the fifth test, the first test material containing polyethyleneimine was used, and 10 cycles of humidified adsorption treatment and reduced pressure steam desorption treatment at a temperature set at 67°C were repeated alternately.

[0071] The results of the fifth test are shown in Figure 24, which summarizes the results of the first to ninth tests. In the fifth test, the CO2 adsorption amount a in the first cycle was 0.0391 g per gram of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0125 g per gram of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 77.0%. The CO2 desorption amount d in the tenth cycle was 0.0218 g per gram of CO2 adsorbent. The change rates d / b=1.74 and d / a=0.56.

[0072] <Sixth Test Results (Example 6)> The results of the sixth test of the CO2 capture process are explained below. In the sixth test, the first test material containing polyethyleneimine was used, and 10 cycles of humidified adsorption treatment and reduced pressure steam desorption treatment at a temperature set to 60°C were repeated alternately.

[0073] The results of the sixth test are shown in Figure 24, which summarizes the results of the first to ninth tests. In the sixth test, the CO2 adsorption amount a in the first cycle was 0.0425 g per gram of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0082 g per gram of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 80.3%. The CO2 desorption amount d in the tenth cycle was 0.0220 g per gram of CO2 adsorbent. The change rates d / b=2.63 and d / a=0.51.

[0074] <Seventh Test Results (Comparative Example 1)> The results of the seventh test of the CO2 capture process are explained below. In the seventh test, a second test material containing isopropylated polyethyleneimine was used, and 10 cycles of humidified adsorption and dry desorption at a temperature of 60°C were repeated alternately.

[0075] FIG. 18 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the seventh test. FIG. 19 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the seventh test. Note that FIG. 19 also shows the saturated CO2 adsorption amount. FIG. 20 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the seventh test. Note that FIG. 20 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p, in addition to the CO2 residual rate. The results of the seventh test are also shown in FIG. 24, which is a summary of the results of the first to ninth tests.

[0076] In the seventh test result, the CO2 adsorption amount a in the first cycle was 0.0314 g per 1 g of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0025 g per 1 g of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 87.7%. The CO2 retention rates from the second cycle onwards are as shown in Figure 20. The CO2 desorption amount d in the tenth cycle was 0.0130 g per 1 g of CO2 adsorbent. The change rates d / b=5.19 and d / a=0.42.

[0077] <Eighth Test Results (Comparative Example 2)> The results of the eighth test of the CO2 capture process are explained below. In the eighth test, a second test material containing isopropyl polyethyleneimine was used, and 10 cycles of humidified adsorption and reduced pressure steam desorption at a temperature of 80°C were repeated alternately.

[0078] FIG. 21 is a graph showing the CO2 adsorption amount and CO2 desorption amount in each cycle of multiple cycles of CO2 capture treatment, among the results of the eighth test. FIG. 22 is a graph showing the change in the total CO2 adsorption amount due to multiple cycles of CO2 capture treatment, among the results of the eighth test. FIG. 23 is a graph showing the CO2 residual rate in each cycle of multiple cycles of CO2 capture treatment, among the results of the eighth test. In addition to the CO2 residual rate, FIG. 23 also shows the saturated CO2 adsorption amount p, the total CO2 adsorption amount q at the 10th cycle, and the value of q / p. The results of the eighth test are also shown in FIG. 24, which is a summary of the results of the first to ninth tests.

[0079] In the eighth test result, the CO2 adsorption amount a in the first cycle was 0.0311 g per gram of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0260 g per gram of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 4.4%. The CO2 retention rates from the second cycle onwards are as shown in Figure 23. The CO2 desorption amount d in the tenth cycle was 0.0330 g per gram of CO2 adsorbent. The change rates d / b=1.26 and d / a=1.05.

[0080] <Ninth Test Results (Comparative Example 3)> The results of the 9th test of the CO2 capture process are explained below. In the 9th test, the first test material containing polyethyleneimine was used, and 10 cycles of humidified adsorption treatment and reduced pressure steam desorption treatment at a temperature set at 100°C were repeated alternately.

[0081] The ninth test result is shown in Figure 24, which summarizes the first to ninth test results. In the ninth test result, the CO2 adsorption amount a in the first cycle was 0.0463 g per gram of CO2 adsorbent, the CO2 desorption amount b in the first cycle was 0.0334 g per gram of CO2 adsorbent, and the average CO2 retention rate c from the first to third cycles was 35.2%. The CO2 desorption amount d in the tenth cycle was 0.0360 g per gram of CO2 adsorbent. The change rates d / b=1.08 and d / a=0.78.

[0082] Fig. 24 is a summary of the first to ninth test results. Referring to Figs. 6 to 23 and the first to sixth test results (Examples 1 to 6) among the first to ninth test results shown in Fig. 24, the CO2 desorption amount is small in the first cycle of the CO2 capture process, but in the second to fifth cycles of the CO2 capture process, the CO2 desorption amount increases as the cycle number increases, and in the fifth to tenth cycles of the CO2 capture process, the CO2 desorption amount stabilizes at a predetermined amount. In the tenth cycle of the CO2 capture process, the CO2 desorption amount is closest to the predetermined amount. Furthermore, in the fifth and subsequent cycles of the CO2 capture process, the total CO2 adsorption amount at the end of the adsorption process is greater than the saturated adsorption amount p.

[0083] Fig. 25 is a diagram showing the relationship between the ratio d / b of the amount of CO2 desorption in the 10th cycle to the amount of CO2 desorption in the 1st cycle and the ratio d / a of the amount of CO2 desorption in the 10th cycle to the amount of CO2 adsorption in the 1st cycle for the first to ninth test results. In Fig. 25, points P1 to P9 correspond to the first to ninth test results.

[0084] The horizontal axis of Figure 25, d / b, represents the rate of change in the amount of CO2 desorption with increasing cycle count. A larger value indicates a greater increase in the amount of CO2 desorption with increasing cycle count, meaning a higher CO2 capture effect from repeating the CO2 capture process multiple times. A smaller value indicates a smaller increase in the amount of CO2 desorption with increasing cycle count, meaning a lower CO2 capture effect from repeating the CO2 capture process multiple times. Specifically, d / b is preferably 1.3 or greater.

[0085] The vertical axis d / a in Figure 25 corresponds to the absolute amount of CO2 desorption with increasing cycle number, and a larger value indicates a higher CO2 capture effect by repeating the CO2 capture process multiple times, while a smaller value indicates a lower CO2 capture effect by repeating the CO2 capture process multiple times because the absolute amount of CO2 desorption is small even when the cycle number is increased due to a too low desorption temperature. Specifically, d / a is preferably 0.5 or more.

[0086] As shown in Fig. 25, at points P1 to P6 corresponding to the first to sixth tests (Examples 1 to 6) among the first to ninth tests, d / b is equal to or greater than the threshold value Th1 (Th1 = 1.3), and d / a is equal to or greater than the threshold value Th2 (Th2 = 0.5). In other words, in the first to sixth tests, a high CO2 capture effect can be obtained at the minimum desorption temperature (i.e., without increasing the energy consumption). In other words, in the region A1 where d / b is equal to or greater than the threshold value Th1 and d / a is equal to or greater than the threshold value Th2, a high CO2 capture effect can be obtained without increasing the energy consumption.

[0087] In contrast, at point P7 corresponding to the seventh test (Comparative Example 1), d / a is less than threshold value Th2. That is, in the seventh test, the desorption temperature was too low at 60°C, so the absolute amount of CO2 desorption was small even with an increased number of cycles, resulting in a low CO2 capture effect. Furthermore, at points P8 and P9 corresponding to the eighth and ninth tests (Comparative Examples 2 and 3), d / b is less than threshold value Th1. That is, in the eighth and ninth tests, although the desorption temperature was sufficiently high, the amount of CO2 desorption hardly increased even with multiple cycles of the CO2 capture process, resulting in a low CO2 capture effect.

[0088] Fig. 26 is a graph showing the relationship between the average value c of the CO2 retention rate after the CO2 desorption process from the first to third cycles and the ratio d / b of the CO2 desorption amount in the tenth cycle to the CO2 desorption amount in the first cycle for the first to ninth test results. In Fig. 26, the x-axis represents the average value c of the CO2 retention rate after the CO2 desorption process from the first to third cycles, and the y-axis represents the ratio d / b of the CO2 desorption amount in the tenth cycle to the CO2 desorption amount in the first cycle. In Fig. 26, points P1 to P9 correspond to the first to ninth test results, and approximate curves for points P1 to P9 are shown.

[0089] As shown in Figure 26, when c = 0, that is, when all CO2 is desorbed from the test material (CO2 adsorbent 111) in the first to third cycles, the amount of CO2 desorbed in the first cycle is equal to the amount of CO2 desorbed in the tenth cycle, and the approximation curve passes through the coordinate point (0, 1). Also, when c ≈ 1, that is, when almost no CO2 is desorbed from the test material (CO2 adsorbent 111) in the first to third cycles, the amount of CO2 desorbed in the first cycle (b) approaches zero and d / b becomes very large, so the approximation curve becomes an asymptote to the straight line at x = 1. This approximation curve is expressed by the following equation (1):

[0090]

number

[0091] The value j is any positive integer. Here, when j = 0.434, the distance from each of points P1 to P9 to the approximation curve of formula (1) is smallest, and the range of x that satisfies y ≥ 1.3 is x ≥ 0.409. In other words, the range of the average value c of the CO2 residual rate after the CO2 desorption treatment from the first to third cycles that satisfies d / b ≥ 1.3 is c ≥ 0.409 (40.9%).

[0092] Fig. 27 is a graph showing the relationship between the average value c of the CO2 residual rate after the CO2 desorption process from the first to third cycles and the ratio d / a of the CO2 desorption amount in the tenth cycle to the CO2 adsorption amount in the first cycle for the first to ninth test results. In Fig. 27, the x-axis represents the average value c of the CO2 residual rate after the CO2 desorption process from the first to third cycles, and the y-axis represents the ratio d / a of the CO2 desorption amount in the tenth cycle to the CO2 adsorption amount in the first cycle. In Fig. 27, points P1 to P9 correspond to the first to ninth test results, and approximate curves for points P1 to P9 are shown.

[0093] As shown in Figure 27, when c = 0, i.e., when all of the CO2 is desorbed from the test material (CO2 adsorbent 111) in the first to third cycles, the amount of CO2 desorbed in the first cycle is equal to the amount of CO2 desorbed in the tenth cycle, and the approximation curve passes through the coordinate point (0, 1). Also, when c = 1, i.e., when no CO2 is desorbed from the test material (CO2 adsorbent 111) in the first to third cycles, the amount of CO2 desorbed in the first cycle (b) is zero, the amount of CO2 desorbed in the tenth cycle (d) is also zero, and d / a is zero, so the approximation curve passes through the coordinate point (1, 0). This approximation curve is expressed as follows:

[0094]

number

[0095] The value n is any positive integer. Here, when n = 3.23, the distance from each of points P1 to P9 to the approximation curve is smallest, and the distance to the approximation curve of formula (2) is also smallest. At this time, the range of x that satisfies y ≧ 0.5 is x ≦ 0.806. In other words, the range of the average value c of the CO2 residual rate after the CO2 desorption treatment from the first to third cycles that satisfies d / a ≧ 0.5 is c ≦ 0.806 (80.6%).

[0096] In short, the CO2 recovery device 1 of the present disclosure can efficiently recover CO2 at the minimum desorption temperature (i.e., without increasing energy consumption) when the average CO2 residual rate after the CO2 desorption process from at least the first to third cycles is within the range of 40.9% to 80.6%.

[0097] <Embodiment 2> In the first to ninth tests, test materials with no CO2 adsorbed were used. In contrast, in the tenth test described in this embodiment, a test material with CO2 pre-adsorbed using a mixed gas of nitrogen and CO2 with a CO2 concentration of 2% was used. In other words, in the tenth test, the CO2 capture process from the first cycle onwards was carried out using a test material with CO2 pre-adsorbed. This will be explained in detail below.

[0098] <Test conditions> In the tenth CO2 capture treatment test, a prior CO2 adsorption treatment (hereinafter referred to as pre-adsorption treatment) and a corresponding CO2 desorption treatment are performed, and then the CO2 adsorption treatment and the CO2 desorption treatment are repeated alternately.

[0099] First, in the pre-adsorption process, a model gas with a volumetric flow rate (SV) of 7.17E+4 / h is passed through a first test material containing polyethyleneimine for 5 minutes at a temperature of 30°C, allowing CO2 to be adsorbed onto the test material. The model gas used here is pure nitrogen gas with 2% CO2 added. The CO2 adsorption amount is calculated based on the difference between the CO2 concentration (2%) of the model gas supplied to the honeycomb (CO2 adsorbent 111) and the CO2 concentration of the model gas that passed through the honeycomb, as well as the gas flow rate. The CO2 concentration is measured using a HORIBA MEXA-1700D CO2 meter, but is not limited to this.

[0100] The CO2 desorption process after the pre-adsorption process involves a reduced-pressure steam desorption process. In the reduced-pressure steam desorption process, the first test material (CO2 adsorbent 111) is heated to 80°C in a thermostatic chamber and steam is passed through the test material at a rate of 0.013 g / min by weight for 5 minutes to desorb the CO2 adsorbed on the test material. The amount of CO2 desorption is calculated based on the flow rate of the diluted gas obtained by combining the steam that has passed through the honeycomb with nitrogen gas at a flow rate of 2 L / min, and the CO2 concentration contained in the diluted gas. The CO2 concentration is measured using, but not limited to, a HORIBA MEXA-1700D CO2 meter.

[0101] The CO2 adsorption process after the pre-adsorption process involves a humidified adsorption process. In the humidified adsorption process, a model gas with a volumetric flow rate (SV) of 2.39E+5 / h is passed through one of the above-mentioned test materials (CO2 adsorbent 111) for 5 minutes at a temperature of 30°C, allowing CO2 to be adsorbed by the test material. The model gas used here is pure nitrogen gas to which 400 ppm of CO2 has been added, humidified to a relative humidity of 60% to 70%. The CO2 adsorption amount is calculated based on the difference between the CO2 concentration (400 ppm) of the model gas supplied to the honeycomb (CO2 adsorbent 111) and the CO2 concentration of the model gas that has passed through the honeycomb, and the gas flow rate. A HORIBA MEXA-1700D CO2 meter is used to measure the CO2 concentration, but other methods are possible.

[0102] <10th test results> The results of the 10th test of the CO2 capture process are explained below. In the 10th test, the first test material containing polyethyleneimine was used, and after pre-adsorption and subsequent desorption, humidified adsorption and reduced pressure steam desorption were alternately repeated three times. In the 10th test, the humidified adsorption and reduced pressure steam desorption processes after pre-adsorption were carried out under the same conditions as the first test.

[0103] Figure 28 shows the CO2 adsorption amount and CO2 desorption amount in each cycle of the multiple-cycle CO2 capture treatment, among the results of the 10th test. Note that Figure 28 also shows the CO2 adsorption amount and CO2 desorption amount in the pre-adsorption treatment. Figure 29 shows the change in the total CO2 adsorption amount due to the multiple-cycle CO2 capture treatment, among the results of the 10th test. Figure 30 shows the CO2 residual rate in each cycle of the multiple-cycle CO2 capture treatment, among the results of the 10th test.

[0104] In the 10th test, the amount of CO2 desorbed in each of the first to third cycles after the pre-adsorption treatment was 0.037 g, which was similar to the amount of CO2 desorbed in the 10th cycle of the first test. This shows that the CO2 capture device 1 can efficiently capture CO2 from the early cycles of the CO2 capture treatment by performing the CO2 capture treatment using the CO2 adsorbent 111 that has a large amount of CO2 adsorbed in advance.

[0105] As described above, the CO2 capture apparatus 1 according to the present disclosure moves to the next cycle of CO2 capture processing while leaving a portion of the CO2 adsorbed in the CO2 adsorbent 111 unrecovered during the CO2 capture processing of a given cycle. As a result, the CO2 capture apparatus 1 according to the present disclosure can desorb and capture a sufficiently high proportion of CO2 from the CO2 adsorbent under low temperature conditions during the next cycle of CO2 capture processing, compared to when all of the CO2 adsorbed in the CO2 adsorbent 111 during a given cycle of CO2 capture processing is captured before moving on to the next cycle of CO2 capture processing. In other words, the CO2 capture apparatus 1 according to the present disclosure can capture CO2 efficiently without increasing energy consumption.

[0106] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention.

[0107] In the present disclosure, part or all of the processing of the CO2 recovery device 1 can be realized by causing a CPU (Central Processing Unit) to execute a computer program.

[0108] The above-described program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSD) or other memory technologies, CD-ROMs, digital versatile discs (DVDs), Blu-ray discs or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0109] The present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the invention. The present invention contributes to carbon neutrality, decarbonization, and the Sustainable Development Goals (SDGs). [Explanation of symbols]

[0110] 1. CO2 capture device 11 CO2 adsorption section 12 CO2 Capture Section 13 Measurement section 14 Control Unit 111 CO2 adsorbent

Claims

1. an adsorption section having a CO adsorbent constituted by a CO adsorbent containing an amino group and a plurality of porous carriers supporting the CO adsorbent, and causing CO contained in a gas supplied from the outside to be adsorbed by the CO adsorbent; a capture unit that desorbs and captures the CO2 adsorbed in the CO2 adsorbent by adjusting the adsorption unit to a temperature higher than that during CO2 adsorption; Equipped with A CO2 recovery device that alternately repeats adsorption of CO2 by the adsorption unit and desorption of CO2 by the capture unit, a measuring unit that measures the amount of CO2 adsorbed by the adsorption unit and the amount of CO2 desorbed by the capture unit; a control unit that controls the amount of CO2 desorption by the capture unit so that, when CO2 adsorption by the adsorption unit and CO2 desorption by the capture unit are alternately repeated three or more cycles, an average of the residual rates of CO2 adsorbed in the CO2 adsorbent in at least the first to third cycles falls within a range of 40.9% to 80.6%; A CO2 recovery device equipped with the above.

2. The residual rate of CO2 is a ratio of the amount of CO2 adsorbed in the CO2 adsorbent after desorption of CO2 by the capture unit to the amount of CO2 adsorbed in the CO2 adsorbent before desorption of CO2 by the capture unit. The CO2 recovery device according to claim 1.

3. The CO2 adsorption conditions by the adsorption unit in each cycle are set to the same conditions, and the CO2 desorption conditions by the capture unit in each cycle are set to the same conditions. The CO2 recovery device according to claim 1.

4. The adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit are alternately repeated five or more cycles. The CO2 recovery device according to claim 1.

5. The capture unit is further configured to desorb and capture the CO2 adsorbed in the CO2 adsorbent by adjusting the adsorption unit to a pressure lower than that during CO2 adsorption. The CO2 recovery device according to claim 1.

6. The capture unit is further configured to desorb and capture the CO2 adsorbed in the CO2 adsorbent by adjusting the humidity of the adsorption unit to a higher humidity than that during CO2 adsorption. The CO2 recovery device according to claim 1.

7. The plurality of porous carriers have a plurality of pores with an average pore diameter of 2 nm to 200 nm and are applied to a substrate having a honeycomb shape. The CO2 recovery device according to claim 1.

8. The porous carriers have a plurality of pores with an average pore diameter of 2 nm to 200 nm and have a pellet shape. The CO2 recovery device according to claim 1.

9. The plurality of porous supports are composed mainly of either silica or alumina. The CO2 recovery device according to claim 1.

10. The CO2 adsorbent is a polyamine containing any one of polyethyleneimine, methylated polyethyleneimine, isopropylated polyethyleneimine, polyallylamine, pentaethylenehexamine, methylated pentaethylenehexamine, isopropylated pentaethylenehexamine, tetraethylenepentamine, methylated tetraethylenepentamine, and isopropylated tetraethylenepentamine, or an amino group-containing compound containing the polyamine. The CO2 recovery device according to claim 1.

11. an adsorption section having a CO adsorbent constituted by a CO adsorbent containing an amino group and a plurality of porous carriers supporting the CO adsorbent, and causing CO contained in a gas supplied from the outside to be adsorbed by the CO adsorbent; a capture unit that desorbs and captures the CO2 adsorbed in the CO2 adsorbent by adjusting the adsorption unit to a temperature higher than that during CO2 adsorption; Equipped with A CO2 recovery method using a CO2 recovery device, which alternately repeats adsorption of CO2 by the adsorption unit and desorption of CO2 by the capture unit, When the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit are alternately repeated three or more cycles, the amount of CO2 desorption by the capture unit is controlled so that the average residual rate of CO2 adsorbed in the CO2 adsorbent in at least the first to third cycles is within the range of 40.9% to 80.6%. CO2 capture method.

12. an adsorption section having a CO adsorbent constituted by a CO adsorbent containing an amino group and a plurality of porous carriers supporting the CO adsorbent, and causing CO contained in a gas supplied from the outside to be adsorbed by the CO adsorbent; a capture unit that desorbs and captures the CO2 adsorbed in the CO2 adsorbent by adjusting the adsorption unit to a temperature higher than that during CO2 adsorption; Equipped with A control program that causes a computer to execute a CO2 capture process using a CO2 capture device that alternately repeats CO2 adsorption by the adsorption unit and CO2 desorption by the capture unit, A process of measuring the amount of CO2 adsorbed by the adsorption unit and the amount of CO2 desorbed by the capture unit; a process of controlling the amount of CO2 desorption by the capture unit so that the average residual rate of CO2 adsorbed in the CO2 adsorbent in at least the first to third cycles is within a range of 40.9% to 80.6% when the adsorption of CO2 by the adsorption unit and the desorption of CO2 by the capture unit are alternately repeated three or more cycles; A control program that causes a computer to execute the above.

Images