Gas recovery device

Abstract

To provide an aggregate module type gas recovery device in which a plurality of adsorption modules are provided and yet dedicated fans respectively corresponding to the adsorption modules are not provided individually and which can reduce work of fans to reduce energy used in gas adsorption operation.SOLUTION: A carbon dioxide recovery device 1 includes: a plurality of modules 11 which execute an adsorption process and a desorption process; and fans 61 provided in a smaller quantity than a quantity of the plurality of modules 11 and configured to supply a gas to the inside of the plurality of modules 11. In each of the plurality of modules 11, a third valve 23 and a fourth valve 24 are respectively provided at an inlet and an outlet of the gas. The fourth valve 24 has a valve aperture which varies according to an adsorption progression of carbon dioxide in the module 11 at which the fourth valve 24 is provided.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a gas recovery device. [Background technology]

[0002] Conventionally, as a gas recovery device, a technology for recovering carbon dioxide from a gas containing carbon dioxide, such as the atmosphere, has been known. This type of technology is described, for example, in Patent Document 1. Patent Document 1 describes a carbon dioxide recovery and release device that uses a blower unit that takes in outside air and sends it to an adsorption section.

[0003] As adsorption by the adsorbent progresses in the adsorption process, the gas adsorption capacity (gas absorption rate) of the adsorbent gradually decreases. At the beginning of the adsorption process, it is desirable to expose the adsorbent to a large amount of air because it can adsorb a large amount of gas, but at the end of the adsorption process, it is not necessary to expose the adsorbent to a large amount of air.

[0004] In Patent Document 1, adsorption units (adsorption modules) containing an adsorbent and delivery units are arranged in a one-to-one relationship. While air blowing is required in the adsorption process, air blowing is not required in the desorption process, so it is possible to stop the fan of the air blowing unit. However, starting the fan requires a large amount of power, and repeated starting and stopping can easily lead to fan failure.

[0005] It is also possible to achieve more efficient gas adsorption by arranging multiple adsorption modules so that adsorption and desorption are performed sequentially with staggered timing. In this case, if multiple adsorption modules are arranged so that adsorption and desorption are performed sequentially with staggered timing and a single fan is used to blow gas through each adsorption module, it is possible to recover gas more efficiently while keeping the fan constantly running.

[0006] For example, if the ratio of the time ta during the adsorption step in which air is circulated through the adsorption module in the gas adsorption step to the total time td, which is the total time not involved in air circulation, such as the preheating step for gas desorption, the desorption step, and the cooling step for adsorption preparation, is, for example, ta:td = 7:1, then a set of 8 modules (7 adsorption modules + 1 desorption module) can be considered, and a positive multiple of this set can be configured as one unit of the gas recovery device. In this case, for example, the step time progression of each module in a set of 8 modules can be delayed by (ta + td) / 8 so that adsorption is completed in order and the desorption step is performed in order, thereby ensuring that some module is always performing the desorption step, thereby enabling efficient heat management. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-98220 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when multiple adsorption modules are arranged and one fan is used to blow air, even if the required airflow volume for each of the multiple adsorption modules differs, the fan must be driven to match the state where the most airflow volume is required, which raises concerns about high fan energy consumption.

[0009] The object of the present disclosure is to provide a gas recovery device that has a plurality of adsorption modules and does not have individual dedicated fans for each adsorption module, and that can reduce the work done by the fans and reduce the energy used for gas adsorption operation. [Means for solving the problem]

[0010] The present disclosure solves the above-mentioned problems by the following means: For ease of understanding, the following description will be given with reference numerals corresponding to the embodiments of the present disclosure, but the present disclosure is not limited to these.

[0011] The first disclosure is a gas recovery device (1) including a plurality of modules (11) having adsorbents (12) therein, which perform an adsorption process of sucking gas containing a gas to be recovered onto the adsorbents (12) to adsorb the gas to be recovered, and a desorption process of heating the adsorbents (12) under reduced pressure to desorb the gas to be recovered from the adsorbents (12), and a number of fans (61) provided that is less than the number of the modules (11) and which supply gas into the plurality of modules (11), wherein each of the plurality of modules (11) is provided with valves (23, 24) at a gas inlet and outlet, respectively, and the valve opening of at least one of the valves (23, 24) changes depending on the progress of adsorption of the gas to be recovered in the module (11) to which the valves (23, 24) are provided.

[0012] The second disclosure is the gas recovery device (1) described in the first disclosure, characterized in that at least one of the valves (23, 24) has a valve opening that decreases with the passage of time of adsorption of the gas to be recovered. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a gas recovery device that has a plurality of adsorption modules and does not have individual dedicated fans for each adsorption module, and that can reduce the work done by the fans and reduce the energy used for gas adsorption operation. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a configuration relating to the flow of liquid in a carbon dioxide recovery device 1, which is a gas recovery device according to one embodiment of the present invention. [Figure 2]1 is a schematic diagram showing a configuration relating to gas flow in a module 11 of a carbon dioxide capture device 1 of the present embodiment. [Figure 3] 1 is a diagram showing an example of a connection configuration between a module 11 and a fan 61. FIG. [Figure 4] 1 is a diagram showing an example of the configuration of a module 11, and also showing a part of the interior of the module 11. FIG. [Figure 5] 2 is a diagram showing an example of the internal configuration of a third valve 23. FIG. [Figure 6] 10 is a diagram showing an example of the internal configuration of a fourth valve 24. FIG. [Figure 7] FIG. 10 is a graph showing the transition of the CO2 concentration at the outlet of the adsorption module when an adsorbent module with an initial CO2 adsorption amount of 0 is supplied with a flow rate of air containing CO2 equal to the CO2 adsorption rate exhibited by the adsorbent when the adsorption amount is 0. [Figure 8] FIG. 8 is a diagram showing the transition of the amount of adsorption under the same conditions as in FIG. 7. [Figure 9] FIG. 9 is a diagram illustrating the transition of the amount of adsorption in addition to FIG. 8 . [Figure 10] FIG. 10 is a diagram showing the required air flow rate and valve opening that change as the processing progresses in each module. [Figure 11] FIG. 10 is a diagram showing the relationship between the opening degree of a butterfly valve 24a and the air flow rate. [Figure 12] This figure shows the air flow rate passing through each module when the opening degree of the butterfly valves 24a of all modules is set to an opening degree that realizes an air flow rate containing a CO2 flow rate that matches the adsorption amount QH at the start of adsorption. [Figure 13] This figure shows the air flow rate passing through each module when the opening degree of the butterfly valve 24a of each module is set to an opening degree that realizes an air flow rate containing a CO2 flow rate that matches the trend of the adsorption amount Q of each module. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] <Overall structure> Fig. 1 is a schematic diagram showing the configuration related to the flow of liquid in a carbon dioxide capture device 1, which is a gas capture device according to one embodiment of the present invention. Fig. 2 is a schematic diagram showing the configuration related to the flow of gas in a module 11 of the carbon dioxide capture device 1 of this embodiment. Note that the configuration related to the flow of gas in the carbon dioxide capture device 1 is omitted from Fig. 1. Note that the following explanation will be given using the carbon dioxide capture device 1, which is an example of a gas capture device, as an example, but the configuration for metering control using a valve according to the present disclosure can be similarly applied to the case of capturing gases other than carbon dioxide.

[0017] The carbon dioxide capture device 1 of this embodiment is applied to, for example, direct air capture (DAC) technology that captures carbon dioxide from the atmosphere in order to reduce the carbon dioxide concentration in the atmosphere. The carbon dioxide captured by the carbon dioxide capture device 1 is stored underground or reused as fuel or material.

[0018] As shown in FIGS. 1 and 2, the carbon dioxide capture device 1 of this embodiment includes a module unit 10, a fan 61, a vacuum pump 62, a carbon dioxide capture pump 63, a heat exchange device 80, and a control device 90.

[0019] The module unit 10 is configured by arranging a plurality of modules 11 in parallel that adsorb carbon dioxide. In this embodiment, a total of 16 modules 11 are arranged by a pair of left and right module units 10.

[0020] As shown in FIG. 2, the module 11 is a carbon dioxide capture module including an adsorbent 12, a first valve 21, a second valve 22, a third valve 23, a fourth valve 24, and an adsorbent temperature sensor 27.

[0021] The adsorbent 12 is disposed inside the module 11 to adsorb carbon dioxide. The adsorbent 12 is a particulate material that has the property of adsorbing carbon dioxide at low temperatures (for example, in the range of -30°C to 50°C) and desorbing (releasing) carbon dioxide at high temperatures (for example, in the range of 50°C to 110°C) when the ambient carbon dioxide concentration is low. Examples of such adsorbent 12 include a solid amine carbon dioxide adsorbent formed by supporting an amine on a porous material such as silica.

[0022] The first valve 21 is an on-off valve arranged at the connection between the module 11 and a carbon dioxide line 103 that captures carbon dioxide. A carbon dioxide capture pump 63 is arranged in the carbon dioxide line 103. The second valve 22 is an on-off valve arranged at the connection between the module 11 and a vacuum line 102 in which a vacuum pump 62 is arranged. The third valve 23 is an on-off valve arranged at the inlet that takes in air and the like into the module 11. The fourth valve 24 is an on-off valve arranged at the connection between the adsorption line 101 and the module 11. A fan 61 is arranged in the adsorption line 101.

[0023] The first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 are all controlled to open and close by a control device 90. The first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 are each configured by, for example, a normally open butterfly valve.

[0024] FIG. 3 is a diagram showing an example of a connection between the modules 11 and the fan 61. FIG. 4 is a diagram showing an example of the configuration of the module 11, and also shows part of the interior of the module 11. In the example shown in FIG. 3, a total of 16 modules 11 are provided on two opposing sides in a direction perpendicular to the extension direction (longitudinal direction) of the piping that is the suction line 101, with eight modules 11 on each side. These modules 11 have fourth valves 24 connected to the suction line 101, and are arranged in parallel to the suction line 101. In other words, the suction line 101 is branched and connected to each of the modules 11. Note that the arrangement of the modules 11 relative to the suction line 101 shown in FIG. 3 is just an example, and other arrangements may also be used.

[0025] As shown in Fig. 4, the module 11 includes a box-shaped housing 15, a heat exchanger 16 disposed therein, and a third valve 23 and a fourth valve 24 provided on two opposing surfaces of the housing 15. The housing 15 is a box-shaped member and contains an adsorbent 12 therein. As shown in Fig. 4, the adsorbent 12 includes, for example, a plurality of thin plate-like fins and tubes (pipes) (not shown), and is filled between the fins of a support body stacked in a bellows shape.

[0026] One fan 61 is provided at the point where the branched portions of the adsorption line 101 converge. When driven, the fan 61 generates a gas flow from "intake" to "exhaust" in each of the multiple modules 11 arranged upstream of the adsorption line 101. This supplies atmospheric air into the module 11.

[0027] For ease of understanding, Fig. 2 shows an example in which one each of the third valve 23 and the fourth valve 24 is provided in one module 11. However, as shown in Figs. 2 and 3, two or more of each of these may be provided in one module 11.

[0028] 5 is a diagram showing an example of the internal configuration of the third valve 23. The right side in FIG. 5 is the atmospheric air inlet side, and the module 11 is connected to the left side. As shown in FIG. 5, the third valve 23 is equipped with an actuator (not shown) that is driven and controlled by the control device 90, and the butterfly valve 23a that is rotated by this actuator rotates between a fully closed state (0° state in FIG. 5) and a fully open state (90° state in FIG. 5). In this way, the third valve 23 switches between blocking and introducing the atmospheric air flowing into the module 11.

[0029] FIG. 6 illustrates an example of the internal configuration of the fourth valve 24. The module 11 is connected to the right side of FIG. 6 , and the fan 61 is connected to the left side via the adsorption line 101. As shown in FIG. 6 , the fourth valve 24 includes an actuator (not shown) driven and controlled by the control device 90. The butterfly valve 24a, which is rotated by the actuator, rotates between a fully closed state (0° in FIG. 6 ) and a fully open state (90° in FIG. 6 ). This allows the fourth valve 24 to switch between blocking and introducing atmospheric air flowing into the module 11. Furthermore, the fourth valve 24 of this embodiment is controlled by the control device 90 during the adsorption process. The valve opening varies depending on the progress of CO2 adsorption in the module 11, and can also be set to an intermediate valve opening between the fully closed state and the fully open state (the metering state in FIG. 6 ). While FIG. 6 illustrates the metering state of the butterfly valve 24a, the opening of the butterfly valve 24a continuously changes between the 0° state and the 90° state. More specifically, in the present embodiment, the valve opening of the fourth valve 24 decreases as the CO2 adsorption time elapses in the adsorption process. The adjustment (adjustment) of the valve opening by the fourth valve 24 will be described in detail later.

[0030] 2, the adsorbent temperature sensor 27 measures the temperature of the adsorbent 12. The measurement information of the adsorbent temperature sensor 27 is transmitted to the control device 90.

[0031] The vacuum line 102 is branched and connected to each of the modules 11. The vacuum pump 62 is disposed at the point where the branched portions of the vacuum line 102 converge. When the vacuum pump 62 is driven, it sucks gas from inside the module 11 through the vacuum line 102, bringing the inside of the module 11 into a vacuum state or close to a vacuum state.

[0032] The carbon dioxide line 103 branches off and is connected to each of the modules 11. A carbon dioxide capture pump 63 is disposed at the point where the branched portions of the carbon dioxide line 103 converge. The carbon dioxide capture pump 63 applies suction force to the carbon dioxide flowing through the carbon dioxide line 103, and stores the captured carbon dioxide in a tank (not shown) for storing carbon dioxide.

[0033] Returning to Fig. 1, the heat exchanger 80 will be described. The heat exchanger 80 supplies thermal energy to heat the interior of each module 11 of the module unit 10 to a predetermined temperature when that module 11 performs the desorption step. The heat exchanger 80 also recovers unnecessary thermal energy when each module 11 performs the adsorption step.

[0034] The heat exchange device 80 of this embodiment includes a heat exchanger 81, a cold water tank 82, a cold water line 111, a hot water tank 83, a hot water line 112, and a three-way valve 30.

[0035] The heat exchanger 81 exchanges heat between the heat medium flowing in the cold water line 111 and the heat medium flowing in the hot water line 112. The heat exchanger 81 is, for example, a heat pump. The heat medium is, for example, a liquid such as water. Due to the heat transfer that occurs in the heat exchanger 81, the heat medium flowing in the cold water line 111 is cooled and the heat medium flowing in the hot water line 112 is heated.

[0036] The cold water tank 82 stores the heat medium flowing through the cold water line 111. The heat medium flowing through the cold water line 111 is stored in the cold water tank 82 and then sent to the heat exchanger 81. The heat medium cooled in the heat exchanger 81 is returned to the cold water tank 82 and then sent to each module 11 through the cold water line 111. A heat exchanger circulating water pump 821 is arranged between the cold water tank 82 and the heat exchanger 81 on the cold water line 111. When the heat exchanger circulating water pump 821 is driven, the heat medium flowing through the cold water line 111 circulates between the cold water tank 82 and the heat exchanger 81.

[0037] The chilled water line 111 branches off and is connected to the upstream and downstream sides of each module 11, connecting the chilled water tank 82 to each module 11. A first chilled water circulation water pump 822 and a second chilled water circulation water pump 823 are disposed on the chilled water line 111 between the chilled water tank 82 and each module 11. A circulation line 824 is disposed on the chilled water line 111, returning from the downstream side of the second chilled water circulation water pump 823 to the upstream side. A circulation valve 825 is disposed on this circulation line 824.

[0038] The hot water tank 83 stores the heat medium flowing through the hot water line 112. The heat medium flowing through the hot water line 112 is stored in the hot water tank 83 and then sent to the heat exchanger 81. The heat medium heated in the heat exchanger 81 is returned to the hot water tank 83 and then sent to each module 11 through the hot water line 112. A heat exchanger circulating water pump 831 is arranged between the hot water tank 83 and the heat exchanger 81 on the hot water line 112. When the heat exchanger circulating water pump 831 is driven, the heat medium flowing through the hot water line 112 circulates between the hot water tank 83 and the heat exchanger 81.

[0039] The hot water line 112 branches off and is connected to the upstream and downstream sides of each module 11, connecting the hot water tank 83 to each module 11. A first hot water circulation water pump 832 and a second hot water circulation water pump 833 are disposed in the hot water line 112 between the hot water tank 83 and each module 11. A circulation line 834 is disposed in the hot water line 112, returning from the downstream side of the second hot water circulation water pump 833 to the upstream side. A circulation valve 835 is disposed in this circulation line 834.

[0040] The three-way valve 30 is connected to the cold water line 111, the hot water line 112, and the module 11. The three-way valve 30 is disposed on each of the upstream and downstream sides of the module 11. The three-way valve 30 is configured to be switchable among a cold water connection state in which the cold water line 111 is connected to the module 11, a hot water connection state in which the hot water line 112 is connected to the module 11, and a disconnection state in which the connection between the cold water line 111 and the hot water line 112 and the module 11 is cut off.

[0041] The flow path switching of the three-way valve 30 is controlled by the control device 90. The heat medium is introduced into the module 11 through the three-way valve 30 arranged on the upstream side, and the heat medium is returned to the heat exchanger 81 side through the three-way valve 30 arranged on the downstream side.

[0042] Next, the control device 90 will be described. 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 opening and closing of the first valve 21, second valve 22, third valve 23, and fourth valve 24 provided in each module 11. The control device 90 also controls the driving of the fan 61, vacuum pump 62, carbon dioxide capture pump 63, heat exchanger circulation water pump 821, first cold water circulation water pump 822, second cold water circulation water pump 823, heat exchanger circulation water pump 831, first hot water circulation water pump 832, second hot water circulation water pump 833, etc., and controls the opening and closing of circulation valve 825 and circulation valve 835.

[0043] The control device 90 is, for example, a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The control device 90 may be configured as one device or as multiple devices.

[0044] <Carbon dioxide capture> Next, the control for capturing carbon dioxide by the control device 90 will be described. The carbon dioxide capture device 1 alternately performs an adsorption process in which the adsorbent 12 in the module 11 adsorbs carbon dioxide in gases such as the air that has been taken in, and a desorption process in which the carbon dioxide adsorbed by the adsorbent 12 is desorbed, and the desorbed carbon dioxide is compressed and stored in a tank (not shown), thereby removing and capturing carbon dioxide from the air. In this embodiment, the adsorption process and the desorption process are performed with a ratio of adsorption process time:desorption process time = 7:1.

[0045] The adsorption process is a process in which carbon dioxide is adsorbed by the adsorbent 12 in the module 11. In the adsorption process, the third valve 23 and the fourth valve 24 of the module 11 are opened, and the first valve 21 and the second valve 22 are closed. The fan 61 is driven to generate a gas flow from upstream to downstream, and a gas containing carbon dioxide (e.g., the atmosphere) is drawn in through the third valve 23. The drawn in gas passes through the adsorbent 12 in the module 11. At this time, the temperature inside the module 11 is room temperature (25°C), and the carbon dioxide in the gas is adsorbed by the adsorbent 12. Gases other than carbon dioxide, such as nitrogen and oxygen, are exhausted to the outside of the carbon dioxide capture device 1 through the fourth valve 24 and the adsorption line 101. In this embodiment, the valve opening degree is adjusted (adjusted) by the fourth valve 24 in the adsorption process.

[0046] The desorption process is a process of desorbing carbon dioxide from the adsorbent 12 in the module 11. In the desorption process, the first valve 21, the third valve 23, and the fourth valve 24 of the module 11 are closed, and the second valve 22 is opened. The vacuum pump 62 is operated to draw air into the inside of the module 11 and reduce the pressure to create a vacuum state or a near-vacuum state. At the same time, the heat exchanger 80 causes a heat medium, which serves as a heat source, to flow through the module 11 to supply thermal energy and raise the temperature of the adsorbent 12 in the module 11.

[0047] By controlling the temperature rise of the adsorbent 12, the adsorbent 12 is also heated to a predetermined temperature (e.g., 80°C) sufficient for the desorption step, and the carbon dioxide adsorbed in the adsorbent 12 is desorbed. Next, the second valve 22, the third valve 23, and the fourth valve 24 are closed, the first valve 21 is opened, and the carbon dioxide recovery pump 63 is driven, and the desorbed carbon dioxide is stored in a tank (not shown) through the carbon dioxide line 103. In this embodiment, each step is controlled so that 12 of the 16 modules 11 perform the adsorption step and the remaining 4 perform the desorption step.

[0048] <Adjustment of valve opening (amount adjustment) by the fourth valve 24> As described above, the fourth valve 24 in this embodiment reduces its valve opening as the CO2 adsorption time elapses during the adsorption process. This control corresponds to the change in the CO2 adsorption rate of the module 11 over time from the start of adsorption. At the start of CO2 adsorption, adsorption occurs very quickly in the adsorbent 12. However, as adsorption progresses, the adsorption rate gradually slows down, eventually approaching the equilibrium adsorption amount, resulting in almost no adsorption. Therefore, the amount of air required to be supplied to the module 11 gradually decreases as adsorption progresses. Therefore, in this embodiment, the valve opening is controlled to decrease over the CO2 adsorption time during the adsorption process, thereby optimizing the amount of air supplied to each module. This control ensures that a sufficient amount of air is supplied to the multiple modules 11. Therefore, the airflow rate required by the fan 61 can also be optimized, significantly reducing the workload of the fan 61 in this embodiment compared to conventional systems. The effect of reducing the workload of the fan will be described below using the 8-joule model illustrated in FIG. 3.

[0049] <CO2 adsorption transition of adsorbent during adsorption process> First, the progress of CO2 adsorption by the adsorbent in the adsorption process will be described. In the following description, the mass transfer coefficient k, equilibrium adsorption amount Q*, initial adsorption amount Q0, and CO2 concentration in the air are assumed to be the following values.

[0050] Mass transfer coefficient k: k = 4 x 10 -4 (1 / s) Equilibrium adsorption amount Q*:Q*=2.3(mol / kg) Initial adsorption amount Q0:Q0=0(mol / kg) CO2 concentration in air: C=400(ppm)

[0051] 3, eight adsorption modules are provided, and the following model explains how adsorption and desorption are performed sequentially with staggered timing for the eight adsorption modules (hereinafter also referred to as adsorption / desorption cycle operation).The ratio of the time length ta of the adsorption step in which air is circulated through the adsorption module to the total time length td not related to air circulation, such as the preheating step for CO2 desorption, the desorption step, and the cooling step for preparation for adsorption, is assumed to be 7:1 as follows:

[0052] ta:td=7:1

[0053] The transition of CO2 adsorption will be explained for this model. Fig. 7 shows the transition of CO2 concentration at the outlet of the adsorption module when an adsorbent module with an initial CO2 adsorption amount of 0 is supplied with a flow rate of CO2-containing air equal to the CO2 adsorption rate exhibited by the adsorbent when the adsorption amount is 0. Fig. 8 shows the transition of the adsorption amount under the same conditions as Fig. 7.

[0054] Immediately after time 0, the outlet CO2 concentration exceeds 0 and gradually approaches 400 ppm over time. Simultaneously, the adsorption amount increases from 0 and gradually approaches the equilibrium adsorption amount of 2.3 mol / kg.

[0055] <Operation of carbon dioxide capture device> Figure 9 is a diagram with additional explanations added to Figure 8, which shows the transition of the adsorption amount. In the adsorption / desorption cycle operation of an actual carbon dioxide capture device, the adsorption amount repeatedly goes back and forth between QL, which is greater than 0, and QH, which is smaller than the equilibrium adsorption amount, and CO2 equivalent to the working capacity (ΔQ = QH - QL), which is the difference between QH and QL, is captured in each cycle.

[0056] As an example, the working capacity is set to 80% of the equilibrium adsorption amount as follows.

[0057] QL = 0.1Q* = 0.23 (mol / kg) QH = 0.9Q* = 2.07 (mol / kg) Therefore, ΔQ = QH - QL = 0.8Q* = 1.84 (mol / kg)

[0058] If the time taken to measure from time 0 for the amount of adsorption to reach QL is tL and the time taken to reach QH is tH, the time ta required for the adsorption step from QL to QH is as follows:

[0059] ta=tH-tL

[0060] Furthermore, the time Td from the time point TH through the desorption step and the like until the amount of adsorption returns from QH to QL again is assumed to be as follows:

[0061] td=ta / 7

[0062] When the working capacity in the cycle adsorption / desorption operation is in the range of 10% (QL) to 90% (QH) of the equilibrium adsorption amount Q*, the difference in the air intake work (J) for the following two types of air flow rate setting methods in the adsorption step is confirmed using a linear driving force model, and the superiority of this method is explained in principle.

[0063] (1) Constant air flow rate drive: When the adsorption step is performed in the section from QL to QH with an air flow rate (constant value) that matches QL. (2) Adsorption amount feedback drive: When the adsorption step is performed with an air flow rate (time-varying value) that matches the adsorption amount Q, which changes from QL to QH.

[0064] When the adsorption step is performed at a constant air flow rate (constant value) that matches QL, the air flow rate F AIR (m 3 / s / kg) can be expressed as follows using the mole to volume conversion factor η:

[0065]

number

[0066] According to the Ergun equation, an empirical formula that expresses the pressure drop (Pa) in an adsorption bed packed with particulate adsorbent, the pressure drop is composed of the sum of a term proportional to the first order and a term proportional to the second order of the superficial air flow velocity (m / s) flowing into the adsorption bed. However, when a thin plate-shaped adsorption bed is used, it is known that the first order component dominates. In this case, the pressure drop P can be calculated using the proportionality coefficient τ. a (Pa) can be expressed as follows:

[0067]

number

[0068] Therefore, the pressure loss P w (W / kg) can be expressed as follows:

[0069]

number

[0070] The outlet CO2 concentration and module flow rate of each adsorption module are measured, and the adsorption amount Q is calculated based on these. When the adsorption step is performed at a flow rate (time-varying value) that matches the adsorption amount Q, which changes from QL to QH, the air flow rate F AIR’ (m 3 / s / kg) can be expressed as follows using the proportionality coefficient η:

[0071]

number

[0072] Here, when an adsorbent with an adsorption amount of 0 starts adsorption at time 0, the adsorption amount Q is expressed as a function of time t as follows:

[0073]

number

[0074] Here, the above equation (d) is a solution to the linear drive model: dQ / dt=k(Q*-Q). Therefore, equation (a') can be rewritten as the following equation (a").

[0075]

number

[0076] Pressure loss P a’ (Pa) can be expressed using (a") as follows:

[0077]

number

[0078] Therefore, the pressure loss P w’ (W / kg) can be expressed as follows:

[0079]

number

[0080] The pressure loss E (J / kg) and E' (J / kg) are calculated by integrating equations (c) and (c') over the time it takes for the adsorption amount to change from QL to QH. This time is calculated by assuming that the adsorption amount starts from 0 and then progresses according to equation (d) from time t L and time t H is calculated and obtained at time t L and QH at time t H can be expressed as follows:

[0081]

number

[0082] Therefore, from equations (d), (e) and (c), the pressure loss E (J / kg) in the case of constant air flow control can be expressed as follows:

[0083]

number

[0084] From equations (e), (f) and (c'), the pressure loss E' (J / kg) in the case of adsorption amount feedback control can be expressed as follows:

[0085]

number

[0086] The calculation conditions here are k=4×10 -4 (1 / s), Q*=2.3 (mol / kg), so if we apply this value to equations (c2) and (c2'), we get the following.

[0087]

number

[0088] From the above, when the working capacity is in the range of 10% (= QL) to 90% (= QH) of the equilibrium adsorption capacity Q*, the air introduction work (J) in the adsorption step is estimated to be 18.2% of the air introduction work in the latter case when the adsorption step is performed at a constant air flow rate consistent with QL, and when the adsorption step is performed at a flow rate (time-varying value) consistent with the adsorption capacity Q that changes from QL to QH. Note that this value of 18.2% was calculated by comparing Equations (C3) and (C'3), which show the pressure loss, by (4840 / 26586×100). This confirms the advantages of the adsorption capacity feedback drive proposed by the present disclosure, which adjusts (meters) the valve opening (amount) using the fourth valve 24. Note that while the model with ta:td = 7:1 was used here, the above advantages would be similar even if, for example, ta:td = 3:1. However, this reduction effect is the result of a comparative evaluation of the air introduction work (J / kg) contributed by the adsorbent.

[0089] If we consider 8 modules (7 adsorption modules + 1 desorption module) as one set and delay the step time transition of each module by (ta + td) / 8 for each of these 8 modules so that the adsorption is completed in order and the desorption step is carried out in order, then overall the adsorption progresses in each module in order, with 7 modules always in the adsorption process and 1 module in the desorption process. In such a case, the appropriate air flow rate required by the 7 modules fluctuates as shown in Figure 10, but the average value is (m 3 / s / kg) is

[0090]

number

[0091] On the other hand, the air flow rate F in the case of constant air flow rate drive shown in formula (a) AIR =F AIRconst can be expressed as follows:

number

[0092] In other words, it was first found that the average air flow rate of 0.3641ηkQ* required for adsorption amount feedback drive is only 40.46% of the flow rate of 0.9ηkQ* required for constant air flow rate drive.

[0093] Next, we will explain how to calculate pressure loss (J / kg). It is necessary to satisfy the pressure constraint requirement that "the pressure loss (Pa) between the upstream and downstream of the module achieved with constant air flow rate drive must occur in the same way even in the case of adsorption amount feedback drive where flow rate is controlled by the downstream valve." The reason for this requirement is explained below.

[0094] (1) As shown in Figures 12 and 13, the module, which is the load, is connected in parallel to the air intake fan. Next, the pressure Pus outside the air inlet valve of the module is constrained to atmospheric pressure Pair. Furthermore, the pressure Pds outside the downstream air outlet valve is constrained to a certain pressure value lower than atmospheric pressure by the driving force of the air fan. This pressure difference Pus-Pds acts as a driving force, and in the case of constant air flow drive, the air flow rate shown in equation (a) is generated.

[0095] (2) Similarly, in the case of adsorption amount feedback drive, this pressure difference is required to ensure that the air flow rate shown in formula (a) is supplied to the module immediately after the start of the adsorption step. Conversely, if this pressure difference does not exist, it is not possible to ensure a sufficient air flow rate for the module immediately after the start of the adsorption step. From the above (1) and (2), it becomes necessary to satisfy the above requirements.

[0096] Due to the above requirements, the differential pressure Pus-Pds (Pa) between the pressures outside the upstream and downstream valves must be the same whether the valve is driven by a constant air flow rate or by adsorption volume feedback. Furthermore, with adsorption volume feedback drive, the pressure loss in the adsorbent itself is reduced by appropriately throttling the air flow rate with the downstream valve, and conversely, a valve pressure loss is added to compensate for this reduction in adsorbent pressure loss. (Because valve pressure loss is determined by this logic, there is actually no need to specify the type of valve; any valve that can smoothly change its characteristics between fully open and fully closed can be used for flow control, regardless of its flow rate characteristics.)

[0097] Under such conditions, the air flow rate differs between the two drive methods, and the air flow rate for the constant air flow drive is 0.9ηkQ. * On the other hand, the average flow rate required for adsorption feedback drive is 0.3641ηkQ * Therefore, the pressure loss (W / kg) of the latter is 40.46% of that of the former. 40.46% is the effect obtained in this example.

[0098] The relationship between the downstream valve opening and the air flow rate when driving at a constant air flow rate is explained with reference to FIG. Modules #1 (hereinafter simply referred to as #1; the same applies to other modules) to #7 are performing the adsorption step, and #8 is performing the desorption step. In the 7 modules of the adsorption step, the adsorption amount on the lower side of the working capacity is always QL=0.1Q * An air flow rate corresponding to #1 is at the beginning of the adsorption step, #7 is at the end of the adsorption step, and after the desorption step of #8 ends, #7 moves on to the desorption step, and at the same time, #8 moves on to the adsorption step. When the valve is fully open (90 degrees), Q = Q * Therefore, the valve opening of each module corresponding to Q=QL is set to 78 degrees instead of 90 degrees (fully open).

[0099] The relationship between the downstream valve opening and the air flow rate in the case of adsorption amount feedback drive will be explained with reference to FIG. Modules #1 to #7 are performing the adsorption step, and #8 is performing the desorption step. The seven modules in the adsorption step are supplied with airflow rates according to the adsorption volume of each module. #1 is at the beginning of the adsorption step, #7 is at the end of the adsorption step, and after the desorption step of #8 ends, #7 moves on to the desorption step, and at the same time, #8 moves on to the adsorption step. When the valve is fully open (90 degrees), Q = Q * 10 corresponds to the valve opening times shown in Fig. 13. Therefore, the valve opening of each module corresponding to Q = QL is set to 78 degrees instead of 90 degrees (fully open). Also, the shaded time intervals in Fig. 10 correspond to the time periods of the valve opening times shown in Fig. 13.

[0100] <Required air flow rate and valve opening> Figure 10 shows the required air flow rate and valve opening degree that change as the treatment progresses in each module. The upper graph in Figure 10 shows the air flow rate, and the lower graph shows the valve opening degree. Note that the air flow rate in Figure 10 is shown as a flow rate per unit mass of adsorbent (mol / s / kg). In Figure 10, the eight modules are numbered "#1" to "#8."

[0101] The air flow rate that corresponds to the maximum adsorption rate QH, which provides working capacity, is 2.07 (mol / s / kg) in Figure 10. The thin lines labeled with the module numbers in Figure 10 represent the air flow rate that corresponds to the adsorption level of each module, varying from 2.07 to 0.23 mol / s / kg. The thick sawtooth line represents the total air flow rate that corresponds to the adsorption level of each module, varying from 0.62 to 0.85 mol / s / kg. When the air flow rate that corresponds to the maximum adsorption rate QH is continuously flowed, the air introduction work required for the adsorbent layer in the latter case is 18.2% of that in the former case. The thick sawtooth line in Figure 10 represents the optimal air flow rate FAIR_opt (mol / s / kg) required by the eight-module carbon dioxide capture system when it is operated steadily under a constant environment.

[0102] <Required valve opening> Based on the "relationship between valve opening and air flow rate" described below and the "required air flow rate" described above, the valve opening (degrees) of each module can be shown as shown in the lower part of FIG. 10. Here, fully closed is 0 degrees and fully open is 90 degrees. The maximum valve opening at the minimum adsorption amount QL is 78 degrees, and the minimum valve opening at the maximum adsorption amount QH is 31.7 degrees. In FIG. 10, the solid line represents the valve opening of module number #1, and the dashed line represents the valve opening of module number #2. Immediately after reaching the maximum adsorption amount, the valve opening quickly moves toward fully closed. As in the example with eight modules, by controlling the fourth valve 24 with the control device 90, the workload required by the fan 61 of this embodiment can be significantly reduced.

[0103] <Required air flow rate> The optimal air flow rate FAIR_opt (mol / s / kg) required by an eight-module carbon dioxide capture unit, obtained when the unit is operated steadily in a constant environment, takes on a sawtooth waveform as mentioned above, with a maximum value of 6.83 and a minimum value of 4.99 relative to an average value of 5.89, with fluctuations of +16.0% and -15.2% from the average. If flow rate feedback operation is performed so that the fan supplies the approximate average value of 5.89 (mol / g / kg) mentioned above, the power consumption of the blower fan can be kept sufficiently low, but the adsorption / desorption profile of each module will deviate slightly from the target value.

[0104] To remedy this, flow rate feedback operation can be performed so that the fan air flow rate becomes the optimal air flow rate FAIR_opt (mol / s / kg). In this case, the following (Phenomenon 1) occurs while (Phenomenon 2) also occurs.

[0105] (Phenomenon 1) The adsorption and desorption characteristics are optimal, and therefore the CO2 yield (tCO2 / year) is also maximized. (Phenomenon 2) Due to slight fluctuations in the operating point of the fan, it becomes impossible to maintain the efficiency of the drive motor and the conversion efficiency of the fan at their optimum points.

[0106] Considering the balance between the above (Phenomenon 1) and (Phenomenon 2), it is possible to select constant control of the air flow rate, variable control, or something in between. In this embodiment, the fan operating state is maintained as constant as possible. This makes it possible to combine and set the region where the fan motor has good efficiency and the region where the fan's axial input power is converted efficiently into air work, resulting in a highly efficient air blower system overall.

[0107] <Relationship between valve opening and air flow rate> FIG. 11 is a diagram showing the relationship between the opening degree of the butterfly valve 24a and the air flow rate. In the case of this embodiment, the differential pressure between the upstream and downstream of the fourth valve 24 is substantially constant. However, when the flow rate is controlled using the butterfly valve 24a, it tends to exhibit characteristics suitable for relatively flow rate control as shown in FIG. 11. Using this characteristic, an appropriate air flow rate can be allocated according to the adsorption amount of each module.

[0108] However, as described above, regardless of the flow rate characteristics of the valve, any valve that can smoothly change the characteristics between fully open and fully closed can be used for the above flow rate control.

[0109] <Estimation of CO2 adsorption amount> The CO2 adsorption amount can be directly estimated by measuring the CO2 concentrations at the inlet and outlet of each module and the air flow rate of each module, and the valve opening degree is controlled according to this estimated value. In this case, the valve control is updated in consideration of the secular change in the adsorption characteristics of the module. Also, the time history characteristics of adsorption may be held in advance as a MAP, and the valve opening degree may be adjusted according to this. Even in the case of control by such a MAP, by typically using the CO2 concentrations at the inlet and outlet of the unit, which is an aggregate of modules, the secular change in the adsorption characteristics is detected, and the valve control is updated in reflection of this, and the performance deterioration of the unit may be minimized.

[0110] As described above, according to the carbon dioxide recovery apparatus 1 of this embodiment, since the opening degree of the fourth valve 24 is changed so as to be an appropriate opening degree according to the progress of carbon dioxide adsorption, the amount of work required by the fan 61 can be reduced.

[0111] (Modified form) Without being limited to the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present disclosure.

[0112] (1) In the embodiment, an example has been described in which the aperture of the fourth valve 24 provided on the outlet side of the module 11 is changed in accordance with the degree of progress of carbon dioxide adsorption. However, this is not limiting, and for example, the aperture of the third valve 23 provided on the inlet side may be changed in accordance with the degree of progress of carbon dioxide adsorption, or the apertures of both the third valve 23 and the fourth valve 24 may be changed.

[0113] (2) In the embodiment, an example has been described in which 16 modules 11 are provided, and adsorption and desorption are performed sequentially in groups of eight modules, so that the ratio of adsorption process time to desorption process time is 7:1. This is not limiting, and the number of modules may be, for example, 24 or 32. Furthermore, for example, when using an adsorbent for which a ratio of 3:1 is appropriate for the adsorption process time to desorption process time, it is appropriate to perform the adsorption process at a ratio of 3:1. In this case, the number of modules 11 is selected to be a multiple of 4, such as 4 or 8. In other words, these numbers are selected to be appropriate values taking into account the ratio of the adsorption process time to the desorption process time of the adsorbent and the scale of the carbon dioxide capture device 1. [Explanation of symbols]

[0114] 1 Carbon dioxide capture device (gas capture device) 10 module units 11 Modules 12 Adsorbent 15 Case 21 First valve 22 Second valve 23 Third valve 23a butterfly valve 24 4th valve 24a butterfly valve 27 Adsorbent temperature sensor 30 Three-way valve 61 fans 62 Vacuum pump 63 Carbon dioxide capture pump 80 Heat exchange equipment 81 Heat exchanger 82 Cold Water Tank 83 Hot Water Tank 90 Control device 101 suction line 102 Vacuum Line 103 Carbon Dioxide Line 111 Cold water line 112 Hot water line 400 Over time 821 Heat exchanger circulation water pump 822 No. 1 cold water circulation water pump 823 Second chilled water circulation water pump 824 Circulation Line 825 Circulation Valve 831 Heat exchanger circulation water pump 832 No. 1 hot water circulation water pump 833 Second hot water circulation water pump 834 Circulation Line 835 Circulation Valve

Claims

1. a plurality of modules each having an adsorbent therein, each performing an adsorption step of sucking a gas containing a target gas into the adsorbent to adsorb the target gas, and a desorption step of heating the adsorbent under a reduced pressure around the adsorbent to desorb the target gas from the adsorbent; a number of fans provided that is less than the number of the modules, the fans supplying gas to the interiors of the plurality of modules; Equipped with Each of the plurality of modules is provided with a valve at each of the gas inlet and outlet, A gas recovery device, wherein at least one of the valves has a valve opening degree that changes depending on the progress of adsorption of the target gas to be recovered in the module in which the valve is provided.

2. 2. The gas recovery device according to claim 1, At least one of the valves has a valve opening that decreases with the passage of time of adsorption of the gas to be recovered; A gas recovery device characterized by:

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