Carbon dioxide recovery device

Abstract

Provided is a carbon dioxide recovery device which is capable of reducing energy required for reducing the internal pressure of a reactor in a desorption step and in which the energy efficiency is high. A carbon dioxide recovery device 1 comprises: a vacuum pump 62 that causes suction to act on reactors 11 which carry out a desorption step, to bring the insides of the reactors to a reduced-pressure state; a communication line 40 that is configured to allow gas to flow therethrough and that is capable of communicating the inside of a first reactor 11A with the inside of another second reactor 11B, which is different from the first reactor 11A; a communication valve 41 that is disposed along the communication line 40 and that opens and closes the route of the communication line 40; and a control device 90 that performs communication control for communicating the inside of the second reactor 11B, which is to be subjected to pressure reduction for carrying out the desorption step via the communication line 40 by controlling the communication valve 41 in an open state, with the inside of the other first reactor 11A, which is in the reduced-pressure state.

Description

Carbon dioxide capture equipment

[0001] The present invention relates to a carbon dioxide capture device.

[0002] Conventionally, techniques for recovering carbon dioxide from a gas containing carbon dioxide, such as the atmosphere, have been known. One example of this type of technique is described in Patent Document 1. Patent Document 1 describes a method for separating gaseous carbon dioxide from a gas mixture by cyclic adsorption / desorption using an adsorbent that adsorbs gaseous carbon dioxide.

[0003] Special table 2017-528318 publication

[0004] In the desorption process of a carbon dioxide capture device, the internal pressure of the reactor holding the adsorbent is reduced from atmospheric pressure to a vacuum state using a vacuum pump, and the temperature of the adsorbent is then raised to desorb carbon dioxide from the adsorbent. After the desorption process, the inside of the reactor must be returned from a vacuum state to atmospheric pressure in order to perform the adsorption process, which adsorbs carbon dioxide onto the adsorbent, necessitating the intake of atmospheric air. Because energy is consumed to create a negative pressure each time the adsorption and desorption processes are alternately performed, conventional technology leaves room for improvement in terms of energy efficiency.

[0005] An object of the present invention is to provide a highly energy-efficient carbon dioxide recovery device that can reduce the energy required to reduce the pressure inside the reactor in the desorption step.

[0006] (1) The present invention relates to a plurality of reactors (for example, reactor 11 described later) that have an adsorbent (for example, adsorbent 12 described later) therein and perform an adsorption step of sucking a gas containing carbon dioxide into the adsorbent to adsorb the carbon dioxide, and a desorption step of heating the adsorbent in a state where the periphery of the adsorbent is reduced in pressure to desorb the carbon dioxide from the adsorbent; a pressure reducing device (for example, vacuum pump 62 described later) that applies a suction force to the reactor that performs the desorption step to reduce the pressure inside the reactor; and a pressure reducing device that is configured to allow gas to flow between the inside of the reactor (for example, first reactor 11A described later) and the reactor. a communication line (for example, the communication line 40 described later) that can communicate with the interior of another reactor (for example, a second reactor 11B described later), a communication opening / closing device (for example, the communication valve 41 described later) that is disposed on the communication line and opens and closes the path of the communication line, and a control device (for example, the control device 90 described later) that controls the communication opening / closing device to be in an open state, thereby performing communication control to communicate, via the communication line, between the interior of the reactor that is depressurized to perform the desorption step and the interior of the other reactor that is in the depressurized state.

[0007] (2) In the carbon dioxide recovery device described in (1) above, the communication control may connect the inside of the reactor that restores the internal pressure of the reduced pressure state to atmospheric pressure in order to perform the adsorption step after the desorption step has been performed with the inside of the reactor that performs the depressurization.

[0008] (3) In the carbon dioxide recovery device described in (1) or (2) above, the control device may perform a first-stage decompression control that connects the inside of the reactor, which is decompressed to perform the desorption step, with the inside of the reactor in the decompressed state via the communication line, and a second-stage decompression control that decompresses the reactor, the internal pressure of which has been reduced by the first-stage decompression control, to a vacuum state or a near-vacuum state using the decompression device.

[0009] (4) The carbon dioxide recovery device described in (3) above may further include an atmospheric opening / closing device (for example, a third valve 23 described later) that opens and closes a path that connects the reactor to the atmosphere, and the control device may restore the pressure inside the reactor to atmospheric pressure by controlling the atmospheric opening / closing device corresponding to the reactor after the internal pressure has increased from the reduced pressure state to an open state through the first-stage decompression control.

[0010] According to the present invention, it is possible to provide a highly energy-efficient carbon dioxide recovery device that can reduce the energy required to reduce the pressure inside the reactor in the desorption step.

[0011] Fig. 1 is a schematic diagram showing a configuration related to gas flow in a carbon dioxide capture device according to one embodiment of the present invention. Fig. 2 is a schematic diagram showing a configuration related to liquid flow in a carbon dioxide capture device of this embodiment. Fig. 3 is a schematic diagram explaining the flow of gas between reactors in a carbon dioxide capture device of this embodiment. Fig. 4 is a timing chart of each process in a plurality of reactors in a carbon dioxide capture device of this embodiment. Fig. 5 is a graph explaining the changes over time in the internal pressure and adsorbent temperature of a first reactor and a second reactor.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] <Overall configuration> Fig. 1 is a schematic diagram showing the configuration related to gas flow in a carbon dioxide capture device 1 according to one embodiment of the present invention. Fig. 2 is a schematic diagram showing the configuration related to liquid flow in the carbon dioxide capture device 1 of this embodiment. Note that the configuration related to liquid flow in the carbon dioxide capture device 1 is omitted from Fig. 1, and the configuration related to gas flow in the carbon dioxide capture device 1 is omitted from Fig. 2.

[0014] 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 a material for resin parts.

[0015] As shown in Figures 1 and 2, the carbon dioxide capture device 1 of this embodiment includes a reactor unit 10, a fan 61, a vacuum pump 62, a carbon dioxide capture pump 63, an intercooler 64, a separator 65, a carbon dioxide tank 66, an inert gas tank 69, a heat exchange device 70, and a control device 90.

[0016] As shown in FIG. 1, the carbon dioxide capture device 1 includes an adsorption line 101, a vacuum line 102, a carbon dioxide line 103, a circulation line 104, and an inert gas supply line 107 as gas flow paths.

[0017] The reactor unit 10 is configured by arranging a plurality of reactors 11 in parallel, each of which adsorbs carbon dioxide. In this embodiment, a total of 16 reactors 11 are arranged in a pair of left and right reactor units 10. The configuration of the reactor 11 will be described later.

[0018] The adsorption line 101 is branched and connected to each of the reactors 11. The fan 61 is disposed 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" through the adsorption line 101 to the reactor 11. This supplies atmospheric air into the reactor 11. A carbon dioxide concentration sensor 611, a humidity sensor 612, and a temperature sensor 613 are disposed at the gas exhaust portion of the adsorption line 101, and measure the carbon dioxide, humidity, and temperature exhausted from the adsorption line 101. Measurement information from the carbon dioxide concentration sensor 611, the humidity sensor 612, and the temperature sensor 613 is transmitted to the control device 90.

[0019] The vacuum line 102 is branched and connected to each of the reactors 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 the inside of the reactor 11 through the vacuum line 102, bringing the inside of the reactor 11 into a vacuum state or a state close to a vacuum state.

[0020] The carbon dioxide line 103 is branched and connected to each of the reactors 11. At the point where the branched portions of the carbon dioxide line 103 converge, a carbon dioxide capture pump 63, an intercooler 64, a separator 65, and a carbon dioxide tank 66 are arranged.

[0021] The carbon dioxide capture pump 63 applies suction force to send the carbon dioxide flowing through the carbon dioxide line 103 to the carbon dioxide tank 66. A one-way valve 631 is arranged upstream of the carbon dioxide capture pump 63 in the carbon dioxide line 103. This prevents gas from flowing back from the intercooler 64 side to the reactor 11 side.

[0022] The intercooler 64 is an intermediate cooling device that cools the high-temperature gas containing carbon dioxide recovered from the reactor 11 and separates it into gas and liquid.

[0023] The water separated into gas and liquid in the intercooler 64 is recovered in a separator 65. A first valve 651 and a second valve 652 are disposed in the separator 65. The first valve 651 opens and closes a path communicating with the gas phase part of the separator 65. The second valve 652 opens and closes a path communicating with the liquid phase part of the separator 65.

[0024] The carbon dioxide tank 66 stores the carbon dioxide recovered through the carbon dioxide line 103. A tank valve 661 is arranged upstream of the carbon dioxide tank 66 in the carbon dioxide line 103. The tank valve 661 is controlled to open and close by the control device 90. In addition, various sensors such as a pressure sensor 662, a flow rate sensor 663, a humidity sensor 664, a temperature sensor 665, and a carbon dioxide concentration sensor 666 are arranged between the tank valve 661 and the carbon dioxide tank 66 in the carbon dioxide line 103.

[0025] In addition to the carbon dioxide line 103, a circulation line 104 that returns ballast to the carbon dioxide capture pump 63 is connected to the carbon dioxide tank 66. A flow rate sensor 667 is disposed in the circulation line 104. In addition, the carbon dioxide tank 66 is provided with a pressure release valve 668 that releases pressure when the pressure reaches or exceeds a predetermined value.

[0026] Next, the inert gas tank 69 will be described. ２ N as an inert gas supplied from a gas cylinder 691 ２ is stored at a certain pressure or higher (for example, 980 kPa). ２ A gas cylinder valve 692 is disposed between the gas cylinders 691. The inert gas tank 69 is also provided with a pressure release valve 693 that releases pressure when the pressure reaches or exceeds a predetermined pressure. A pressure sensor 694 is disposed inside the inert gas tank 69. Pressure information measured by the pressure sensor 694 is transmitted to the control device 90.

[0027] The inert gas tank 69 is connected to the carbon dioxide line 103 via an inert gas supply line 107. An inert gas valve 695 is disposed on the inert gas supply line 107. The inert gas valve 695 is controlled to open and close by the control device 90.

[0028] The heat exchanger 70 will be described with reference to Fig. 2. The heat exchanger 70 supplies thermal energy for heating the interior of each reactor 11 of the reactor unit 10 to a predetermined temperature when the reactor 11 performs the desorption step. The heat exchanger 70 also recovers unnecessary thermal energy when the reactor 11 performs the adsorption step.

[0029] The heat exchange device 70 of this embodiment includes a heat source circuit 80 , a cold water line 111 , a hot water line 112 , a three-way valve 30 , a bypass path 31 , and a bypass valve 32 .

[0030] The heat source circuit 80 primarily comprises a heat source device 81, a cold water tank 82, a hot water tank 83, a cold water circulation pump 821, and a hot water circulation pump 831. Heat exchange occurs between cold water flowing through the cold water line 111 as a cooling heat medium and hot water flowing through the hot water line 112 as a heating heat medium. The heat source device 81 is, for example, a heat pump. The cold water tank 82 stores the cooling heat medium, and the hot water tank 83 functions as a buffer for storing the heating heat medium. The cold water circulation pump 821 circulates the cooling heat medium between the cold water tank 82 and the heat source device 81. The hot water circulation pump 831 circulates the heating heat medium between the hot water tank 83 and the heat source device 81. Heat transfer occurring in the heat source circuit 80 cools the cooling heat medium flowing through the cold water line 111 and heats the heating heat medium flowing through the hot water line 112. The heat medium is, for example, a liquid such as water, with cold water being the heat medium for cooling and hot water being the heat medium for heating.

[0031] The cold water line 111 is a pipe through which cold water flows as a cooling heat medium. The cold water line 111 is branched and connected to the upstream and downstream sides of each reactor 11, connecting the cold water tank 82 to each reactor 11. Of the cold water lines 111, the line connected to the upstream side of each reactor 11 is referred to as a cold water supply line 111a, and the line connected to the downstream side of each reactor 11 is referred to as a cold water return line 111b.

[0032] The cold water supply line 111a is connected in parallel to the multiple reactors 11, and cold water can be supplied in parallel to each reactor 11. A first cold water circulation water pump 822 and a second cold water circulation water pump 823 are arranged in the cold water supply line 111a. The first cold water circulation water pump 822 and the second cold water circulation water pump 823 are, for example, cascade pumps.

[0033] Additionally, a circulation line 824 is disposed in the chilled water supply line 111a, returning from the downstream side of the second chilled water circulation water pump 823 to the upstream side. A safety valve 825 is disposed in this circulation line 824. The safety valve 825 relieves pressure when the pressure in the system between the second chilled water circulation water pump 823 and the chilled water line 111 exceeds a certain level, thereby suppressing a pressure increase. By arranging the safety valve 825, which relieves pressure in the event of a pressure abnormality in the chilled water line 111, in parallel with the second chilled water circulation water pump 823, it is possible to achieve both a high flow rate circulation by the second chilled water circulation water pump 823 and safe operation. Furthermore, suppressing pressure increases enables power savings.

[0034] The cold water recovery line 111b is also connected in parallel to the plurality of reactors 11, and the recovery of cold water after cooling can also be carried out in parallel for each reactor 11.

[0035] The hot water line 112 is a pipe through which hot water as a heat medium for heating flows. The hot water line 112 is branched and connected to the upstream and downstream sides of each reactor 11, connecting the hot water tank 83 to each reactor 11. Of the hot water lines 112, the line connected to the upstream side of each reactor 11 is referred to as a hot water supply line 112a, and the line connected to the downstream side of each reactor 11 is referred to as a hot water return line 112b.

[0036] The hot water supply line 112a is connected in parallel to the multiple reactors 11, and hot water can be supplied to each reactor 11 in parallel. A first hot water circulation water pump 832 and a second hot water circulation water pump 833 are arranged in the hot water supply line 112a. The first hot water circulation water pump 832 and the second hot water circulation water pump 833 are, for example, cascade pumps. By using a cascade pump that generates a large amount of heat when driven, it is possible to further heat the heat medium passing through the first hot water circulation water pump 832 and the second hot water circulation water pump 833.

[0037] In addition, a circulation line 834 is arranged in the hot water supply line 112a, returning from the downstream side of the second hot water circulation water pump 833 to the upstream side. A safety valve 835 is arranged in this circulation line 834. The safety valve 835 relieves pressure when the pressure in the system between the second hot water circulation water pump 833 and the hot water line 112 exceeds a certain level, thereby suppressing pressure buildup. By arranging the safety valve 835, which relieves pressure in the event of a pressure abnormality in the hot water line 112, in parallel with the second hot water circulation water pump 833, it is possible to achieve both high-flow circulation by the second hot water circulation water pump 833 and safe operation. Furthermore, suppressing pressure buildup enables power saving.

[0038] The hot water return line 112b is also connected in parallel to the plurality of reactors 11, and the hot water after heating can also be recovered in parallel for each reactor 11.

[0039] The three-way valve 30 is connected to the cold water line 111, the hot water line 112, and the reactor 11. The three-way valve 30 is disposed on each of the upstream and downstream sides of the reactor 11. The three-way valve 30 is configured to be able to select, by flow path switching, a cold water connection state in which the cold water line 111 is connected to the reactor 11, a hot water connection state in which the hot water line 112 is connected to the reactor 11, and a cut-off state in which the cold water line 111 and the hot water line 112 are cut off from the reactor 11.

[0040] The flow path switching of the three-way valve 30 is controlled by the control device 90. The heat medium is introduced into the reactor 11 through the three-way valve 30 arranged on the upstream side, and the heat medium is returned to the heat source device 81 side through the three-way valve 30 arranged on the downstream side.

[0041] The bypass path 31 is a flow path that allows the heat transfer medium to move between the reactors 11. The bypass path 31 connects two reactors 11. The reactors 11 connected by the bypass path 31 may be adjacent reactors 11 or may be reactors 11 that are not adjacent but located apart.

[0042] The bypass valve 32 is disposed in the bypass path 31. The bypass valve 32 is disposed in each of the plurality of bypass paths 31. The bypass valve 32 is controlled to open and close by the control device 90.

[0043] Next, the control device 90 will be described. The control device 90 controls the operation of devices used for adsorption and desorption of carbon dioxide, such as driving and stopping the devices. 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 a single device or as a plurality of devices. The control device 90 may also be configured using an electric circuit such as a relay.

[0044] <Configuration of reactor> Fig. 3 is a schematic diagram illustrating the flow of gas between the reactors 11 of the carbon dioxide capture device 1 of this embodiment. Fig. 3 shows four reactors 11 out of the multiple reactors 11.

[0045] The reactor 11 is a carbon dioxide recovery reactor equipped with an adsorbent 12, a first valve 21, a second valve 22, a third valve 23, a fourth valve 24, a communication line 40, a communication valve 41, a pressure sensor 25, a carbon dioxide sensor 26, and a temperature sensor 27.

[0046] The adsorbent 12 is disposed inside the reactor 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.

[0047] 3 are a first reactor 11A, a second reactor 11B, a third reactor 11C, and a fourth reactor 11D. The first reactor 11A is connected to the second reactor 11B via a communication line 40. The second reactor 11B is connected to the third reactor 11C via a communication line 40. The third reactor 11C is connected to the fourth reactor 11D via a communication line 40. The fourth reactor 11D is connected to the first reactor 11A via a communication line 40. In the following description, matters common to the first reactor 11A to the fourth reactor 11D may be referred to simply as reactor 11, with the alphabet omitted.

[0048] The first valve 21 is an on-off valve disposed at a connection between a carbon dioxide line 103 for recovering carbon dioxide and the reactor 11. A carbon dioxide recovery pump 63 is disposed in the carbon dioxide line 103.

[0049] The second valve 22 is an on-off valve disposed at the connection between the reactor 11 and a vacuum line 102 in which the vacuum pump 62 is disposed.

[0050] The third valve 23 is an on-off valve disposed at the inlet for taking in the atmosphere and the like into the reactor 11 .

[0051] The fourth valve 24 is an on-off valve disposed at the connection between the adsorption line 101 and the reactor 11 .

[0052] The communication line 40 is a flow path that allows gas to move between the reactors 11. The communication line 40 functions as a gas-phase flow path that connects the inside of one reactor 11 to the inside of another reactor 11. The reactors 11 connected by the communication line 40 may be adjacent reactors 11 or may be reactors 11 that are not adjacent but located apart.

[0053] The communication valve 41 is an on-off valve disposed in the communication line 40. When the communication valve 41 is in an open state, the interiors of the reactors 11 connected via the communication line 40 are communicated with each other.

[0054] The first valve 21, the second valve 22, the third valve 23, the fourth valve 24, and the communication valve 41 are all controlled to open and close by the control device 90. The first valve 21, the second valve 22, the third valve 23, the fourth valve 24, and the communication valve 41 are each configured by, for example, a normally open butterfly valve.

[0055] The pressure sensor 25 measures the internal pressure of the reactor 11. The carbon dioxide sensor 26 measures the carbon dioxide concentration inside the reactor 11. The temperature sensor 27 measures the temperature of the adsorbent 12. Measurement information from the pressure sensor 25, the carbon dioxide sensor 26, and the temperature sensor 27 is sent to the control device 90.

[0056] <Recovery of Carbon Dioxide> Next, a description will be given of control for recovering carbon dioxide by the control device 90. The control device 90 of this embodiment recovers carbon dioxide in each reactor 11 by performing control to repeat each process in a cycle of an adsorption process, a depressurization process, a temperature increase process, a desorption process, a temperature decrease process, and a pressure recovery process.

[0057] The adsorption step is a step of adsorbing carbon dioxide to the adsorbent 12 in the reactor 11. In the adsorption step, the third valve 23 and the fourth valve 24 of the reactor 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., atmospheric air) is drawn in through the third valve 23. The drawn in gas passes through the adsorbent 12 in the reactor 11. At this time, the inside of the reactor 11 is cooled to room temperature (25°C) by the cold water, 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.

[0058] The depressurization step is a step of reducing the pressure inside the reactor 11 after the adsorption step to a vacuum state or a near-vacuum state. In the depressurization step of this embodiment, two-stage control, namely, a first-stage depressurization control and a second-stage depressurization control, is performed.

[0059] In the first-stage depressurization control, a communication control is executed in which the communication valve 41, which is normally controlled to a closed state, is controlled to an open state, thereby communicating the inside of the reactor 11 performing the depressurization step with the inside of the reactor 11 performing the repressurization step. Note that in the communication control, the first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 of each reactor 11 connected via the communication line 40 are controlled to a closed state. Since the reactor 11 performing the repressurization step is in a vacuum state or a state close to a vacuum, gas moves from the inside of the reactor 11 performing the depressurization step, which is at atmospheric pressure, to the inside of the reactor 11 performing the repressurization step, which is in a vacuum state, due to the communication, and the internal pressure of the reactor 11 performing the depressurization step decreases.

[0060] In the second-stage depressurization control, the first valve 21, the third valve 23, and the fourth valve 24 of the reactor 11 are closed, and the second valve 22 is opened. The vacuum pump 62 is operated, a suction force acts on the inside of the reactor 11, and the inside of the reactor 11 becomes a depressurized state (a vacuum state or a state close to a vacuum).

[0061] The temperature-raising step is a step of heating the adsorbent 12 by the heat exchanger 70 to a temperature at which desorption is possible. In the temperature-raising step, the three-way valve 30 of the heat exchanger 70 is controlled to a hot water connection state, whereby hot water is supplied to the reactor 11 and the temperature of the adsorbent 12 is raised. In the temperature-raising step, the adsorbent 12 is also heated to a predetermined temperature (e.g., 80°C) sufficient for the desorption step.

[0062] The desorption process is a process in which the carbon dioxide adsorbed by the adsorbent 12 in the adsorption process is desorbed and recovered in the carbon dioxide tank 66. In the desorption process, 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 carbon dioxide desorbed through the carbon dioxide line 103 is stored in the carbon dioxide tank 66.

[0063] The temperature-reducing step is a step in which the adsorbent 12 is cooled by the heat exchanger 70 after the desorption step, and the temperature of the adsorbent 12 is reduced to room temperature. In the temperature-reducing step, the three-way valve 30 of the heat exchanger 70 is controlled to a cold water connection state, cold water is supplied to the reactor 11, and the temperature of the adsorbent 12 is reduced. In the temperature-reducing step, the adsorbent 12 is cooled to room temperature.

[0064] The pressure recovery step is a step of returning the internal pressure of the reactor 11, which has been in a vacuum state or a near-vacuum state in the desorption step, to atmospheric pressure. In the pressure recovery step of this embodiment, two-stage control, namely, a first-stage pressure recovery control and a second-stage pressure recovery control, is performed.

[0065] In the first-stage pressure recovery control, a communication control is executed in which the communication valve 41 is controlled to an open state, thereby communicating the inside of the reactor 11 performing the pressure recovery step with the inside of the reactor 11 performing the depressurization step. Note that in the communication control, the first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 of each reactor 11 connected via the communication line 40 are controlled to a closed state. Because the reactor 11 performing the depressurization step is at a pressure approximately equal to atmospheric pressure, gas moves from the inside of the reactor 11 performing the depressurization step, which is at atmospheric pressure, to the inside of the reactor 11 performing the pressure recovery step, which is in a vacuum state, due to the communication, and the internal pressure of the reactor 11 performing the pressure recovery step increases.

[0066] In the second-stage control for pressure recovery, the first valve 21 and the second valve 22 of the reactor 11 are closed, and the third valve 23 or the fourth valve 24 is opened, the inside of the reactor 11 is brought into communication with the atmosphere, and the internal pressure of the reactor 11 is restored to atmospheric pressure. Note that in the second-stage control for pressure recovery, a dedicated valve for pressure recovery may be provided, and the controller 90 may control the valve to an open state, thereby restoring the pressure to atmospheric pressure.

[0067] The control device 90 of this embodiment performs control to capture carbon dioxide by varying the timing of executing each process for each reactor 11. Fig. 4 is a timing chart of each process of the multiple reactors 11 of the carbon dioxide capture device 1 of this embodiment. Fig. 4 shows each process of the first reactor 11A to the fourth reactor 11D shown in Fig. 3. Fig. 5 is a graph illustrating the changes over time in the internal pressure and adsorbent temperature of the first reactor 11A and the second reactor 11B.

[0068] As shown in Figures 4 and 5, a depressurization step is performed in the first reactor 11A. In this example, since the depressurization step is performed first in the first reactor 11A and there is no reactor 11 in a depressurized state, the depressurization second-stage control is performed without going through the depressurization first-stage control. The internal pressure of the first reactor 11A is reduced by driving the vacuum pump 62, resulting in a vacuum state or a state close to vacuum. Furthermore, in the first reactor 11A, a heating step is performed after the depressurization step is started, and the temperature of the adsorbent 12 is raised to a temperature at which desorption is possible.

[0069] After the depressurization step and the temperature increase step, a desorption step is carried out in the first reactor 11A to desorb carbon dioxide. In the desorption step, the carbon dioxide is recovered in the carbon dioxide tank 66 by driving the carbon dioxide recovery pump 63. After the desorption step, the temperature of the adsorbent 12 in the first reactor 11A is reduced to room temperature. After the temperature decrease step, a pressure recovery step is carried out.

[0070] The pressure recovery step of the first reactor 11A and the pressure reduction step of the second reactor 11B are performed in parallel. In this embodiment, the first-stage pressure recovery control of the first reactor 11A and the first-stage pressure reduction control of the second reactor 11B are performed simultaneously. The control device 90 controls the communication valve 41 on the communication line 40 connecting the first reactor 11A and the second reactor 11B to an open state, thereby communicating the inside of the first reactor 11A with the inside of the second reactor 11B. The gas inside the second reactor 11B, which is at a pressure close to atmospheric pressure before the pressure reduction step is performed, moves to the inside of the first reactor 11A, which is in a vacuum or near-vacuum state. This causes a negative pressure baton pass, in which the internal pressure of the first reactor 11A increases and the internal pressure of the second reactor 11B decreases. While the first stage of pressure recovery control for the first reactor 11A and the first stage of pressure reduction control for the second reactor 11B are being executed simultaneously, the vacuum pump 62 is not driven.

[0071] Next, a second-stage pressure recovery control for the first reactor 11A and a second-stage pressure reduction control for the second reactor 11B are executed. In the second-stage pressure recovery control for the first reactor 11A, the third valve 23, the fourth valve 24, or both of them of the first reactor 11A whose internal pressure has increased in the first-stage pressure recovery control are controlled to be open, and the internal pressure of the first reactor 11A is returned to atmospheric pressure.

[0072] In the second-stage depressurization control of the second reactor 11B, the first valve 21, the third valve 23, the fourth valve 24, and the communicating valve 41 of the first reactor 11A, whose internal pressure has been reduced by the first-stage depressurization control, are controlled to be in a closed state, the second valve 22 is controlled to be in an open state, and the vacuum pump 62 is driven. Since the vacuum pump 62 is driven in a state in which the internal pressure has been reduced in advance, it is possible to reduce the driving energy required to bring the inside of the reactor 11 into a vacuum state or a near-vacuum state.

[0073] After the pressure recovery step, the first reactor 11A transitions to the adsorption step. After the depressurization step, the second reactor 11B sequentially undergoes the heating step, desorption step, temperature reduction step, and pressure recovery step, similar to the first reactor 11A. The pressure recovery step of the second reactor 11B is carried out in parallel with the depressurization step of the third reactor 11C, and a negative pressure is passed between the second reactor 11B and the third reactor 11C, similar to the relationship between the first reactor 11A and the second reactor 11B. After the pressure recovery step, the second reactor 11B transitions to the adsorption step, and after the depressurization step, the third reactor 11C sequentially undergoes the heating step, desorption step, temperature reduction step, and pressure recovery step. The pressure recovery step of the third reactor 11C is also carried out in parallel with the depressurization step of the fourth reactor 11D, and a negative pressure baton is passed between the third reactor 11C and the fourth reactor 11D. After the pressure recovery step, the third reactor 11C transitions to the adsorption step, and after the depressurization step, the fourth reactor 11D also sequentially carries out the temperature increase step, desorption step, temperature decrease step, and pressure recovery step. The pressure recovery step of the fourth reactor 11D is carried out in parallel with the depressurization step of the first reactor 11A after the adsorption step is carried out, and a negative pressure baton is passed between the fourth reactor 11D and the first reactor 11A.

[0074] As described above, the carbon dioxide capture device 1 of this embodiment includes a plurality of reactors 11 having adsorbents 12 therein, each of which performs an adsorption process in which a gas containing carbon dioxide is sucked into the adsorbent 12 to adsorb the carbon dioxide, and a desorption process in which the adsorbent 12 is heated under a reduced pressure around the adsorbent 12 to desorb the carbon dioxide from the adsorbent 12; a vacuum pump (decompression device) 62 that applies a suction force to the reactor 11 performing the desorption process to reduce the pressure inside the reactor 11; and a gas supply system configured to allow gas to flow therethrough. a communication line 40 capable of communicating the interior of the first reactor 11A with the interior of a second reactor 11B different from the first reactor 11A; a communication valve (communication on / off device) 41 disposed on the communication line 40 for opening and closing the path of the communication line 40; and a control device 90 for controlling the communication valve 41 to an open state, thereby communicating the interior of the second reactor 11B, which is depressurized for performing the desorption step, with the interior of the other first reactor 11A, which is in a depressurized state, via the communication line 40.

[0075] This allows O ２ The inside of the first reactor 11A, which is in a reduced pressure state (vacuum state or near-vacuum state) due to purging, is connected to the inside of the second reactor 11B, which must be reduced pressure to carry out the subsequent desorption step, and gas movement occurs, thereby reducing the internal pressure of the second reactor 11B. Since the internal pressure of the second reactor 11B can be reduced by utilizing the negative pressure energy of the first reactor 11A, for which the desorption step has been completed, as decompression energy for the second reactor 11B, the driving energy of the vacuum pump 62 can be reduced.

[0076] In addition, in the communication control of this embodiment, the inside of the first reactor 11A, which returns the internal pressure from a reduced pressure state to atmospheric pressure in order to perform the adsorption process after the desorption process is performed, is connected to the inside of the second reactor 11B, which performs the decompression.

[0077] This allows the pressure recovery step of the first reactor 11A and the pressure reduction step of the second reactor 11B to be carried out in parallel, thereby speeding up the carbon dioxide recovery cycle and enabling efficient carbon dioxide recovery.

[0078] In addition, in this embodiment, the control device 90 executes a first-stage decompression control that connects the inside of the second reactor 11B, which is decompressed to perform the desorption process, with the inside of the first reactor 11A, which is in a decompressed state, via the communication line 40, and a second-stage decompression control that decompresses the second reactor 11B, whose internal pressure has been reduced by the first-stage decompression control, to a vacuum state or a state close to vacuum using the vacuum pump 62.

[0079] As a result, even if the first-stage depressurization control is unable to achieve a sufficiently reduced pressure, the internal pressure of the second reactor 11B can be reliably maintained at a vacuum or near-vacuum state by driving the vacuum pump 62. Even in this case, the first-stage depressurization control does not require driving the vacuum pump 62, so the driving energy of the vacuum pump 62 can be reduced.

[0080] Moreover, the carbon dioxide recovery device 1 of this embodiment further includes a third valve (opening / closing device for atmosphere) 23 that opens and closes the path that connects the reactor 11 with the atmosphere, and the control device 90 controls the third valve 23 corresponding to the first reactor 11A after the internal pressure has increased from the reduced pressure state to an open state through the first stage decompression control, thereby restoring the pressure inside the first reactor 11A to atmospheric pressure.

[0081] When the reactor 11A is released from a vacuum or near-vacuum state to atmospheric pressure, a pressure difference can cause a sudden movement of gas, resulting in loud noise. In this regard, according to the configuration of this embodiment, the first reactor 11A is released to atmospheric pressure after the internal pressure has risen from the reduced pressure state to a certain extent, thereby avoiding loud noise and strain on the device caused by the pressure difference.

[0082] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications. Furthermore, the effects described in the above embodiments are merely preferred effects, and the present invention is not limited to those described in the above embodiments.

[0083] REFERENCE SIGNS LIST 1 Carbon dioxide capture device 11 Reactor 11A First reactor 11B Second reactor 11C Third reactor 11D Fourth reactor 12 Adsorbent 21 First valve 22 Second valve 23 Third valve 24 Fourth valve 40 Communication line 41 Communication valve 62 Vacuum pump 63 Carbon dioxide capture pump 90 Control device

Claims

1. A plurality of reactors having an adsorbent material inside, which perform an adsorption step of drawing a gas containing carbon dioxide onto the adsorbent material to adsorb the carbon dioxide, and a desorption step of heating the adsorbent material under reduced pressure to desorb the carbon dioxide from the adsorbent material. Each of the multiple reactors is branched and connected to an adsorption line through which the gas flows during the adsorption process, A vacuum line is branched and connected to each of the multiple reactors, A vacuum device connected to the vacuum line and applying a suction force to the reactor that performs the desorption process to reduce the pressure inside the reactor, A communication line is configured to allow gas to flow, and to connect the interior of the reactor with the interior of another reactor different from the said reactor, A communication opening / closing device is arranged in the aforementioned communication line and opens and closes the path of the aforementioned communication line, A control device that controls the communication opening / closing device to be in the open state, thereby controlling the inside of the reactor that performs the depressurization process to be carried out via the communication line to communicate with the inside of the other reactor that is in a depressurized state, Equipped with, Carbon dioxide capture device.

2. In the aforementioned communication control, the interior of the reactor, which restores the internal pressure of the depressurized state to atmospheric pressure after the desorption process has been performed and in order to perform the adsorption process, is connected to the interior of the reactor that performs the depressurization. The carbon dioxide recovery apparatus according to claim 1.

3. The control device is A first-stage depressurization control that connects the interior of the reactor, which performs depressurization to carry out the desorption process, to the interior of the reactor in the depressurized state via the aforementioned communication line, A second stage of pressure reduction control is performed on the reactor, whose internal pressure has been reduced in the first stage of pressure reduction control, by using the pressure reduction device to reduce the pressure to a vacuum state or a near-vacuum state. A carbon dioxide recovery device according to claim 1 or 2.

4. The system further includes an atmospheric switching device that opens and closes a path connecting the reactor to the atmosphere, The control device is The first stage of pressure reduction control controls the atmospheric pressure opening / closing device corresponding to the reactor after the internal pressure has risen from the reduced pressure state to an open state, thereby restoring the internal pressure of the reactor to atmospheric pressure. The carbon dioxide recovery apparatus according to claim 3.