Carbon dioxide capture device
The carbon dioxide recovery device with multiple modules and staggered operations addresses the inefficiencies of single-adsorbent systems by enabling efficient control and reduced energy consumption through shared components and optimized module timing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HONDA MOTOR CO LTD
- Filing Date
- 2024-02-05
- Publication Date
- 2026-05-15
Smart Images
Figure 0007860160000001 
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Abstract
Description
Technical Field
[0006] , , ,
[0001] The present invention relates to a carbon dioxide recovery device.
Background Art
[0002] Conventionally, technologies for recovering carbon dioxide from gases containing carbon dioxide such as the atmosphere are known. For example, Patent Document 1 describes such a technology. Patent Document 1 describes a method of separating gaseous carbon dioxide from a gas mixture by cyclic adsorption / desorption using an adsorbent that adsorbs gaseous carbon dioxide.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] When a carbon dioxide recovery device is configured with a single huge adsorbent, the components of each device such as a fan, a vacuum pump, and a heat source operate intermittently in the adsorption process and the desorption process. Intermittent operation requires a large output instantaneously.
[0005] By separating the adsorbent into a plurality of modules and shifting the operation timing, it is possible to use inexpensive devices with a small capacity without reducing the amount of carbon dioxide recovered per unit time. However, even if the operation timing is shifted, it is difficult to evenly disperse the output, and there is room for improvement in the prior art from the viewpoint of efficiently controlling a plurality of modules.
[0006] An object of the present invention is to provide a carbon dioxide recovery device capable of efficiently controlling a plurality of modules having an adsorbent.
Means for Solving the Problems
[0007] (1) The present invention is a carbon dioxide recovery device (for example, a carbon dioxide recovery device 1, described later) comprising: a plurality of modules (for example, a module 11, described later) having an adsorbent (for example, an adsorbent 12, described later) inside, which perform an adsorption step of drawing a gas containing carbon dioxide onto the adsorbent to adsorb the carbon dioxide, and a desorption step of heating the adsorbent while the surrounding area is under reduced pressure to desorb the carbon dioxide from the adsorbent; a fan (for example, a fan 20, described later) that supplies gas into the inside of the module; a heat source (for example, a heat source 23, described later) that supplies heat to heat the adsorbent in the module; and a vacuum pump (for example, a first vacuum pump 21, a second vacuum pump 22, described later) that draws gas from inside the module, wherein at least one of the fan, the heat source and the vacuum pump is shared by the plurality of modules, and the number of modules M is set based on the following formula (1), where N is a natural number and R is the ratio of the adsorption time of the adsorbent to the desorption time. M = N × (R + 1) ... Formula (1)
[0008] (2) In the carbon dioxide recovery apparatus described in (1) above, the processes for carrying out the adsorption step and the desorption step may be carried out at different times so as not to be performed at the same time among the multiple modules.
[0009] (3) In the carbon dioxide recovery apparatus described in (2) above, the time calculated by dividing the sum of the adsorption time and the desorption time by the number of modules M may be set as the time difference in the operating timing between the modules.
[0010] (4) In the carbon dioxide recovery device described in (2) or (3) above, the number of modules M may be 10 or more. [Effects of the Invention]
[0011] According to the present invention, it is possible to provide a carbon dioxide recovery device that can efficiently control multiple modules having adsorbent materials. [Brief explanation of the drawing]
[0012] [Figure 1] This is a schematic diagram showing the configuration of a carbon dioxide capture device according to one embodiment of the present invention. [Figure 2] This is a bar graph showing the cycles of each process in the adsorption and desorption steps of this embodiment. [Figure 3] This is a tree diagram showing the influencing factors in the ratio of adsorption time to desorption time. [Figure 4] This table shows the relationship between each process and time in the adsorption and desorption steps of this embodiment. [Figure 5] This graph shows the change in power output for each component within a single module. [Figure 6] This graph shows the change in power output for each device in the four modules. [Figure 7] This graph shows an example of the processing timing for each of the eight modules. [Figure 8] This graph shows the relationship between the number of modules and the operating range of the first vacuum pump. [Figure 9] This graph shows the relationship between the number of modules and the operating range of the second vacuum pump. [Modes for carrying out the invention]
[0013] Embodiments of the present invention will be described below with reference to the drawings.
[0014] <Overall Structure> Figure 1 is a schematic diagram showing the configuration of a carbon dioxide capture device 1 according to one embodiment of the present invention.
[0015] The carbon dioxide capture device 1 of this embodiment is applied, for example, to direct air capture (DAC) technology, which captures carbon dioxide from the atmosphere to reduce the concentration of carbon dioxide in the atmosphere. The carbon dioxide captured by the carbon dioxide capture device 1 is stored underground or reused as fuel or material.
[0016] As shown in FIG. 1, the carbon dioxide recovery apparatus 1 of the present embodiment includes a plurality of modules 11, a fan 20, a first vacuum pump 21, a second vacuum pump 22, a heat source 23, and a control device 90.
[0017] The module 11 is a carbon dioxide recovery module that includes an adsorbent 12 for adsorbing carbon dioxide inside. The adsorbent 12 is a particulate member, and adsorbs carbon dioxide in a low temperature state (for example, in the range of -30°C to 50°C), and has the property of desorbing (releasing) carbon dioxide in a high temperature state (for example, in the range of 50°C to 110°C) and a low ambient carbon dioxide concentration state. Examples of such an adsorbent 12 include a solid amine carbon dioxide adsorbent in which an amine is supported on a porous material such as silica.
[0018] A plurality of modules 11 are arranged. The number of modules is set based on the ratio of the adsorption time and the desorption time described later.
[0019] When the fan 20 is driven, it causes a gas flow from "intake" to "exhaust" to the module 11 through the piping. Thereby, the atmosphere is supplied into the module 11. The fan 20 causes a gas flow from "intake" to "exhaust" to a plurality of modules 11 through the branched and connected piping.
[0020] [[ID=I8]] The first vacuum pump 21 applies a suction force to send the carbon dioxide desorbed from the adsorbent 12 inside the module 11 to a tank (not shown) in the desorption process described later. The first vacuum pump 21 applies a suction force to a plurality of modules 11 through the branched and connected piping.
[0021] The second vacuum pump २२ applies a suction force to depressurize the inside of the module 11 and bring it to a vacuum state or close to a vacuum state. The second vacuum pump 22 applies a suction force to a plurality of modules 11 through the branched and connected piping.
[0022] The heat source 23 supplies thermal energy to heat the adsorbent 12 inside each module 11 of the module unit 10 to a predetermined temperature when the module 11 performs the desorption process. In this embodiment, the heat source 23 also functions as a heat exchanger that recovers excess thermal energy when the module 11 performs the adsorption process. The heat source 23 supplies or recovers thermal energy for each of the multiple modules 11.
[0023] The heat source 23 is composed of, for example, piping and a heat pump connected to each module 11. The heat source 23 may be a heater or a steam generator.
[0024] The control device 90 controls the operation of each part of the carbon dioxide capture device 1. The control device 90 controls the operation of devices used for carbon dioxide adsorption and desorption, such as driving and stopping. The control device 90 controls the operation of the fan 20, the first vacuum pump 21, the second vacuum pump 22, the heat source 23, etc.
[0025] The control device 90 is, for example, a computer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The control device 90 may consist of one unit or multiple units.
[0026] <Relationship between adsorption and desorption processes> The carbon dioxide recovery device 1 alternately performs an adsorption process in which carbon dioxide from gases such as the inhaled atmosphere is adsorbed onto the adsorbent material 12 in the module 11, and a desorption process in which the carbon dioxide adsorbed onto the adsorbent material 12 is desorbed, thereby removing and recovering carbon dioxide from the air.
[0027] Referring to Figure 2, the process for recovering carbon dioxide using the control device 90 will be described. Figure 2 is a bar graph showing the cycle of each process in the adsorption and desorption steps of this embodiment.
[0028] The adsorption process involves adsorbing carbon dioxide onto the adsorbent material 12 within module 11. During the adsorption process, module 11 is drawn in by the drive of fan 20, and an adsorption process is performed. The drawn-in gas passes through the adsorbent material 12 within module 11. At this time, the temperature inside module 11 is room temperature (25°C), and the carbon dioxide in the gas is adsorbed onto the adsorbent material 12. Other gases, such as nitrogen and oxygen, are exhausted to the outside of the carbon dioxide recovery device 1.
[0029] The desorption process is a process of desorbing carbon dioxide from the adsorbent 12 inside the module 11. In the heating process of the desorption process, thermal energy is supplied to the module 11 by the heat source 23, and the adsorbent 12 is heated to a predetermined temperature (for example, 90°C) sufficient for the desorption process. An O2 purging process is performed during the heating process. In the O2 purging process, the second vacuum pump 22 operates to draw air into the inside of the module 11, reduce the pressure, and perform O2 scavenging to create a vacuum or near-vacuum state inside the module 11. In the desorption process of the adsorbent 12, the carbon dioxide adsorbed on the adsorbent 12 is desorbed, and the carbon dioxide is sent to a tank (not shown) by suction of the first vacuum pump 21. After the desorption process, the adsorbent 12 is cooled.
[0030] During the cooling process, a pressure restoration process is performed to return the internal pressure of module 11 to its original level. The start of the pressure restoration process marks the start of the next adsorption process.
[0031] The adsorption time, which indicates the duration of the adsorption process, and the desorption time, which indicates the duration of the desorption process, are determined by the equipment configuration, operating conditions, etc. Next, referring to Figure 3, we will explain an example of factors influencing the adsorption time and desorption time, where R is the ratio of adsorption time to desorption time. Figure 3 is a tree diagram showing the factors influencing the ratio R of adsorption time to desorption time.
[0032] As shown in Figure 3, the factors influencing the adsorption time can be broadly divided into structure, control, and material. The structure is determined by factors such as air-material contact and leakage. The heat exchanger specifications are such as the fin tube pitch. Leakage is the amount of gas leakage from module 11. Control is the airflow rate and SOC setting. The SOC (State of Charge) setting is the range of carbon dioxide adsorption amount for which adsorption and desorption are repeatedly controlled. The material is based on the reaction rate of the adsorbent 12.
[0033] Among the factors influencing adsorption time, heat exchanger specifications, leaks, airflow, and SOC settings are specifications that include other performance aspects. The reaction rate is determined based on the materials constituting the adsorbent 12. The reaction rate is a relatively difficult influencing factor to control.
[0034] The factors influencing the desorption time can be broadly categorized into CO2 partial pressure, material temperature, material performance, heating time, and control (SOC setting). The CO2 partial pressure is determined by the internal pressure of module 11 and the amount of H2O adsorbed on the adsorbent 12. The material temperature is the temperature of the adsorbent 12. Material performance is determined by the adsorption performance of the adsorbent 12, etc. The heating time is determined by the heater capacity of the heat source 23, the heating temperature difference, desorption heat, the stack capacity of the adsorbent 12, the heat loss of module 11, the heat exchanger specifications such as the fin tube pitch, and the flow rate of the heating medium such as antifreeze (LLC liquid). Control is determined by the SOC setting.
[0035] Among the factors influencing the desorption time, the CO2 partial pressure, H2O content, material temperature, heater capacity, desorption heat, adsorbent 12 stack capacity, module 11 heat loss, heat exchanger specifications such as fin tube pitch, heating medium flow rate, and control (SOC setting) are all specifications that include other performance aspects. Material performance is a relatively difficult-to-control influencing factor determined by the adsorbent 12 used.
[0036] The ratio of adsorption time to desorption time (adsorption time / desorption time) is set based on these influencing factors. Next, with reference to Figure 4, a specific example of the ratio of adsorption time to desorption time (adsorption time / desorption time) will be explained. Figure 4 is a table showing the relationship between each process and time in the adsorption and desorption processes of this embodiment.
[0037] In the example shown in Figure 4, the total time for adsorption is 94.6 minutes, and the total time for desorption is 31.5 minutes. The adsorption time is three times the desorption time. The ratio of adsorption time to desorption time is calculated by rounding to the nearest whole number. If the adsorption time is 90 minutes, the desorption time is 30 minutes, and one cycle is 120 minutes, then the ratio of adsorption time to desorption time is 3:1, and the ratio of adsorption time to desorption time (adsorption time / desorption time) R is 3. The following describes the case where the ratio of adsorption time to desorption time (adsorption time / desorption time) R of the carbon dioxide recovery device 1 in this embodiment is 3.
[0038] <Setting the number of modules> Next, we will explain how to set the number of modules. First, we will explain a comparison between the case where the adsorption and desorption processes are performed with one module 11 and the case where the adsorption and desorption processes are performed with multiple modules 11 (four modules).
[0039] Figure 5 is a graph showing the power changes of each component in a single module 11. Figure 5 shows the changes in power (output) of the fan 20, heat source 23, second vacuum pump 22 for O2 scavenging, and first vacuum pump 21 for desorption over time during the repressurization process, adsorption process, O2 purging process, desorption process, and cooling process when carbon dioxide is recovered in a single module 11.
[0040] As shown in Figure 5, when a single module 11 performs a cycle to capture carbon dioxide, the fan 20 operates during the adsorption process but does not operate during the desorption process. Conversely, the heat source 23 operates during the desorption process but does not operate during the adsorption process. The second vacuum pump 22 for O2 scavenging operates only during the O2 purging process, and the first vacuum pump 21 for desorption also operates only during the desorption process and does not operate otherwise. In this way, the operation of each device is intermittent, and a large output is required instantaneously.
[0041] Figure 6 is a graph showing the power changes of each device in the four modules 11. In Figure 6, the output (power) changes of the fan 20, heat source 23, second vacuum pump 22 for O2 scavenging, and first vacuum pump 21 for desorption are shown as solid lines over time in each of the processes: repressurization, adsorption, O2 purging, desorption, and cooling, when carbon dioxide recovery is performed in the four modules 11 with staggered cycle times. In addition, the operational changes of a single module 11 are also illustrated with a dashed line in Figure 6 for comparison.
[0042] As shown in Figure 6, when the carbon dioxide capture cycles of the four modules 11, consisting of the first module 11, the second module 11, the third module 11, and the fourth module 11, are differed and each process is performed, the fan 20 and heat source 23 operate continuously, the output changes become nearly constant, and the operation is no longer intermittent. In addition, the output peaks for each process become smaller for the second vacuum pump 22 for O2 scavenging and the first vacuum pump 21 for desorption. In this way, by operating multiple modules 11 in a staggered manner, the fan 20 and heat source 23 can operate efficiently in continuous operation. Furthermore, the maximum capacity required for each piece of equipment, such as the fan 20, heat source 23, second vacuum pump 22 for O2 scavenging, and first vacuum pump 21 for desorption, can be reduced, making it possible to use relatively smaller and less expensive equipment.
[0043] Next, referring to Figure 7, a method for controlling the output of each device in a carbon dioxide capture device 1 using multiple modules 11 to be equal will be described. Figure 7 is a graph showing an example of the processing timing for each of the eight modules 11.
[0044] Figure 7(a) shows the change in the output of each device over time when the operating timings of all eight modules 11 are staggered. Numbers 1 to 8 in the operating schedule in the graph represent the operation of each module 11. For example, "1" in the graph represents the first module 11, "2" represents the second module 11, "3" represents the third module 11, and so on, from 4 to 8, corresponding to the number of modules 11.
[0045] In the example shown in Figure 7(a), the adsorption and detachment processes are controlled so that the operating timings of all eight modules 11 are staggered and the time differences between modules 11 are equal. Therefore, only one module 11 operates simultaneously.
[0046] The time difference in the operating timing between the eight modules 11 can be calculated using the following formula (2). The time difference between modules is the interval between the timings in which the same operation is performed between different modules 11. For example, the time difference between the start of the adsorption process in the first module 11 and the start of the adsorption process in the second module 11 is the time difference in operating timing. The operating timing is delayed in the order of the first module 11, the second module 11, the third module 11... to the eighth module 11. The time difference in operating timing between each module 11 is the time difference calculated using the following formula (2). Time difference between modules = (Adsorption time + Desorption time) / Number of modules ... Formula (2) In this example, since there is no module 11 to synchronize with, there is only one module 11 operating concurrently.
[0047] Figure 7(b) shows the change in the output of each device over time when the operating timing of eight modules 11 is staggered, with four modules 11 forming one set. In the example in Figure 7(b), a total of eight modules 11 are operating in two sets. The processing of the first module 11 of the first set and the fifth module 11 of the second set are synchronized, the processing of the second module 11 of the first set and the sixth module 11 of the second set are synchronized, the processing of the third module 11 of the first set and the seventh module 11 of the second set are synchronized, and the processing of the fourth module 11 of the first set and the eighth module 11 of the second set are synchronized. In this example, since there are two synchronized modules 11, two modules 11 operate simultaneously.
[0048] As can be seen from comparing Figure 7(a) and Figure 7(b) (see the dashed line in the graph), staggering the operating timings of all eight modules as in Figure 7(a) reduces the operational fluctuations of the second vacuum pump 22 for O2 scavenging and the first vacuum pump 21 for desorption compared to the case where modules 11 operate simultaneously at the same timing as in Figure 7(b). Thus, it can be seen that having different operating timings for all modules 11 reduces the required capacity of the equipment compared to having all modules 11 operate at the same timing.
[0049] Next, the method for setting the number of modules 11 will be explained. As explained with reference to Figures 5 and 6, having multiple modules 11 is more advantageous in terms of device configuration than having a single module, by staggering the operating timings. In this embodiment, the number of modules 11 is set to correspond to the following formula (1). In formula (1), M represents the number of modules 11, N represents a natural number, and R represents the ratio of adsorption time to desorption time (adsorption time / desorption time). M = N × (R + 1) ... Formula (1)
[0050] In this embodiment, the adsorption time:desorption time ratio is 3:1, so the ratio R (adsorption time / desorption time) is 3. Therefore, the appropriate number of modules 11 is 4 (N=1), 8 (N=2), 12 (N=3), 16 (N=4), and so on.
[0051] According to formula (1), M may be a number with decimal places, but the value of N is set so that the actual number of modules set is a natural number. For example, when R=2.5, the natural numbers are even numbers such as 2, 4, 6, etc., and the appropriate number of module 11s is 7 (N=2), 14 (N=4), 21 (N=6). Also, when R=3.5, the natural numbers are even numbers such as 2, 4, 6, etc., and the appropriate number of module 11s is 9 (N=2), 18 (N=4), 27 (N=6). In other words, N is set so that the number of module 11s is a natural number.
[0052] Thus, there are multiple optimal numbers of modules 11 selected by R, which is the ratio of adsorption / desorption time. Next, with reference to Figures 8 and 9, the preferred range of the number of modules 11 will be explained. Figure 8 is a graph showing the relationship between the number of modules 11 and the operating variation range of the first vacuum pump 21. Figure 9 is a graph showing the relationship between the number of modules 11 and the operating variation range of the second vacuum pump 22. In both Figures 8 and 9, R, which is the ratio of adsorption time to desorption time (adsorption time / desorption time), is set to 3. The operating variation range is the force and output result required to drive the equipment (first vacuum pump 21, second vacuum pump 22) shown in the graph of Figure 6.
[0053] The graph in Figure 8 shows that the operating range of the second vacuum pump 22 tends to decrease as the number of modules 11 increases when R=3. In particular, the operating range decreases significantly when the number of modules 11 exceeds 10. Furthermore, when the number of modules 11 exceeds 20, there is a very gradual but slightly increasing tendency for the operating range to increase.
[0054] The graph in Figure 9 also shows that the operating range of the first vacuum pump 21 tends to decrease as the number of modules 11 increases when R=3. Similar to the second vacuum pump 22, the operating range decreases significantly when the number of modules 11 exceeds 10. Here too, when the number of modules 11 exceeds 20, there is a very gradual but slightly increasing tendency for the operating range to increase.
[0055] In both Figure 8 and Figure 9, the preferred number of modules 11 is 10 or more. Furthermore, from the graphs in Figure 8 and Figure 9, it can be seen that, from the perspective of reducing the range of operational variation, the more preferable range is 10 or more but less than 20 modules.
[0056] As described above, the carbon dioxide recovery device 1 of this embodiment includes a plurality of modules 11 that have an adsorbent 12 inside and perform an adsorption step of drawing a gas containing carbon dioxide onto the adsorbent 12 to adsorb carbon dioxide, and a desorption step of heating the adsorbent 12 in a reduced-pressure state to desorb carbon dioxide from the adsorbent 12, a fan 20 that supplies gas into the inside of the modules 11, a heat source 23 that supplies heat to heat the adsorbent 12 of the modules 11, and a first vacuum pump 21 and a second vacuum pump 22 that draw gas into the inside of the modules 11. At least one of the fan 20, the heat source 23, the first vacuum pump 21 and the second vacuum pump 22 is shared by the plurality of modules 11, and the number of modules 11 M is set based on the following formula (1), where N is a natural number and R is the ratio of the adsorption time of the adsorbent 12 to the desorption time. M = N × (R + 1) ... Formula (1)
[0057] This allows the number of modules 11 and the operating schedule of each module 11 to be set according to the respective time ratios of adsorption and desorption of the adsorbent material 12, thereby enabling continuous operation of the adsorption and desorption processes in each module 11 and reducing energy consumption. Since energy consumption can be reduced, it is possible to select equipment with smaller output and capacity (fan 20, heat source 23, first vacuum pump 21 and second vacuum pump 22), thereby reducing operating costs and manufacturing costs.
[0058] Furthermore, in this embodiment, the processes for performing the adsorption and desorption steps are executed at staggered intervals so that they do not occur simultaneously among the multiple modules 11. This reliably prevents situations in which the equipment (fan 20, heat source 23, first vacuum pump 21 and second vacuum pump 22) operate simultaneously, causing a momentary increase in output.
[0059] Furthermore, in this embodiment, the time calculated by dividing the sum of the adsorption time and desorption time by the number of modules 11 (M) is set as the time difference in the operating timing between modules 11. This makes it possible to make the operating time and output of each device more uniform during the operating time, making the operations required to realize each process of the adsorption and desorption processes more consistent, and improving energy efficiency.
[0060] Furthermore, in this embodiment, the number of modules 11, M, is 10 or more. This allows for a smaller range of operational fluctuations, as shown in Figures 8 and 9, making it possible to select equipment with lower output and capacity.
[0061] Although embodiments of the present invention have been described above, the invention is not limited to the embodiments and modifications described above. Furthermore, the effects described in the above embodiments are merely a list of preferred effects and are not limited to those described in the above embodiments. [Explanation of Symbols]
[0062] 1. Carbon dioxide capture device 11 modules 12 Adsorbent 20 Fans 21. First Vacuum Pump 22. Second Vacuum Pump 23 Heat source
Claims
1. Multiple modules having an adsorbent inside, which perform an adsorption step of drawing a gas containing carbon dioxide onto the adsorbent to adsorb the carbon dioxide, and a desorption step of heating the adsorbent while the area around it is under reduced pressure to desorb the carbon dioxide, A fan that supplies gas to the inside of the module, A heat source for supplying heat to heat the adsorbent material of the module, A vacuum pump for sucking gas from inside the module, Equipped with, At least one of the fan, the heat source, and the vacuum pump is shared among the multiple modules. The time from the start of heating while the surrounding area of the adsorbent is under reduced pressure to the start of the repressurization process to return the adsorbent to its reduced pressure state is defined as the desorption time, which represents the time of the desorption process. The time from the start of the repressurization process to the point when heating begins while the area around the adsorbent is under reduced pressure is defined as the adsorption time, which represents the duration of the adsorption process. If the number of modules M is a natural number N, and R is the ratio obtained by dividing the adsorption time of the adsorbent by the desorption time, It is set based on the following formula (1): A carbon dioxide recovery device in which the operation timings of the adsorption step and the desorption step are staggered so that they do not occur at the same time among the multiple modules. M = N × (R + 1) ... Formula (1)
2. The time calculated by dividing the sum of the adsorption time and the detachment time by the number of modules (M) is set as the time difference in the operating timing between the modules. The carbon dioxide recovery apparatus according to claim 1.
3. The number of modules M is 10 or more. The carbon dioxide recovery apparatus according to claim 2.