Carbon dioxide recovery device

Abstract

The problem to be solved by the present invention is to provide a carbon dioxide recovery device with high energy efficiency, which can utilize adsorption heat and can suppress the energy required for raising the temperature of an adsorbent in a desorption step. In order to solve the problem, a carbon dioxide recovery device (1) is provided with: a module (11) that has an adsorbent (12) therein, and that executes an adsorption step in which a gas containing carbon dioxide is sucked into the adsorbent (12) and the adsorbent (12) adsorbs carbon dioxide, and a desorption step in which the adsorbent (12) adsorbs carbon dioxide by heating the surroundings of the adsorbent in a depressurized state; desorbing the carbon dioxide from the adsorber 12; and a cold water tank 82 for storing a cooling medium for cooling the module 11. Furthermore, in the adsorption step, when the difference between the temperature of the adsorber 12 and the temperature of the cooling medium in the cold water tank 82 is equal to or greater than a first threshold value, the cooling medium is caused to flow to the module 11 for heat recovery.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide recovery device. Background Art

[0002] Conventionally, a technique for recovering carbon dioxide from a gas containing carbon dioxide such as the atmosphere has been known. As a document describing such a technique, for example, there is Patent Document 1. In Patent Document 1, the following method is described: gaseous carbon dioxide is separated from a gas mixture by performing cyclic adsorption / desorption using an adsorbent that adsorbs gaseous carbon dioxide.

[0003] [Prior Art Documents]

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-528318 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] However, in the desorption step of desorbing the carbon dioxide adsorbed by the adsorbent from the adsorbent, it is necessary to keep the adsorbent at a high temperature state. In order to raise the temperature of the adsorbent from room temperature to a temperature at which desorption can be performed, a large amount of heat energy from the outside is required. On the other hand, in the adsorption step of adsorbing carbon dioxide to the adsorbent, adsorption heat is generated in the adsorbent, but this adsorption heat is not utilized. In the prior art, there is still room for improvement in terms of improving the energy efficiency required for raising the temperature of the adsorbent.

[0008] An object of the present invention is to provide a carbon dioxide recovery device with high energy efficiency, which can utilize adsorption heat and can suppress the energy required for raising the temperature of the adsorbent in the desorption step.

[0009] [Means for Solving the Problems]

[0010] The present disclosure solves the above problems by the following means. In addition, for ease of understanding, symbols corresponding to the embodiments of the present disclosure are attached for explanation, but it is not limited thereto.

[0011] The first disclosure is a carbon dioxide recovery device (1), comprising: a module (11) having an adsorbent (12) inside and performing an adsorption process and a desorption process. The adsorption process is to attract a gas containing carbon dioxide to the aforementioned adsorbent (12) to cause the adsorbent (12) to adsorb the aforementioned carbon dioxide. The desorption process is to desorb the aforementioned carbon dioxide from the adsorbent (12) by heating the periphery of the adsorbent (12) under a reduced pressure state; and a tank (82) for storing a cooling medium for cooling the aforementioned module (11). And, in the aforementioned adsorption process, when the difference between the temperature of the aforementioned adsorbent (12) and the temperature of the aforementioned cooling medium in the aforementioned tank (82) is equal to or greater than a first threshold value, the aforementioned cooling medium is caused to flow to the aforementioned module (11) for heat recovery.

[0012] The second disclosure is that in the carbon dioxide recovery device (1) described in the first disclosure, when the difference between the inlet temperature at the position where the aforementioned cooling medium enters the aforementioned module (11) and the outlet temperature at the position where the aforementioned cooling medium leaves the aforementioned module (11) is less than a second threshold value, the flow of the aforementioned cooling medium to the aforementioned module (11) is stopped.

[0013] The third disclosure is that in the carbon dioxide recovery device (1) described in the first disclosure or the second disclosure, when the difference between the temperature of the aforementioned adsorbent (12) and the temperature of the aforementioned cooling medium in the aforementioned tank (82) is less than a third threshold value, the flow of the aforementioned cooling medium to the aforementioned module (11) is stopped.

[0014] (Advantages of the Invention)

[0015] According to the present disclosure, a carbon dioxide recovery device with relatively high energy efficiency can be provided, which can utilize adsorption heat and can suppress the energy required for the adsorbent to heat up in the desorption process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram showing the configuration related to the flow of the liquid of the carbon dioxide recovery device 1 according to an embodiment of the present invention.

[0017] Figure 2 is a schematic diagram showing the configuration related to the flow of the gas of the module 11 of the carbon dioxide recovery device 1 according to the present embodiment.

[0018] Figure 3 is a schematic diagram showing the heat supply path when adsorption heat recovery is not performed in the adsorption process.

[0019] Figure 4 is a schematic diagram showing the heat supply path when adsorption heat recovery is being performed in the adsorption process.

[0020] Figure 5It is a diagram for explaining the heat transfer of module 11 in the adsorption process, including when adsorption heat recovery is not carried out and when adsorption heat recovery is in progress.

[0021] Figure 6 It is a flowchart showing an example of the operation process of adsorption heat recovery carried out by the carbon dioxide recovery device of this embodiment. Detailed Embodiment

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] <Overall Structure>

[0024] Figure 1 It is a schematic diagram showing the structure related to the flow of liquid in the carbon dioxide recovery device 1 of an embodiment of the present invention. Figure 2 It is a schematic diagram showing the structure related to the flow of gas in module 11 of the carbon dioxide recovery device 1 of this embodiment. Additionally, in Figure 1 the illustration of the structure related to the flow of gas in the carbon dioxide recovery device 1 is omitted.

[0025] The carbon dioxide recovery device 1 of this embodiment is applied, for example, to the direct air capture technology (Direct Air Capture, DAC) for recovering carbon dioxide in the atmosphere to reduce the carbon dioxide concentration in the atmosphere. The carbon dioxide recovered by the carbon dioxide recovery device 1 is stored underground or reused as fuel or materials.

[0026] As Figure 1 and Figure 2 shown, the carbon dioxide recovery device 1 of this embodiment includes a module unit 10, a fan 61, a vacuum pump 62, a carbon dioxide recovery pump 63, a heat exchange device 80, and a control device 90.

[0027] The module unit 10 is composed of a plurality of modules 11 for adsorbing carbon dioxide arranged in parallel. In this embodiment, a total of 16 modules 11 are arranged by means of a pair of left and right module units 10.

[0028] As Figure 2 shown, the module 11 is a carbon dioxide recovery module, which includes 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.

[0029] The adsorbent 12 is disposed inside the module 11 to adsorb carbon dioxide. The adsorbent 12 is a granular member and has the following properties: it adsorbs carbon dioxide in a low-temperature state (for example, in the range of -30°C to 50°C), and desorbs (releases) carbon dioxide in a high-temperature state (for example, in the range of 50°C to 110°C) and when the concentration of carbon dioxide in the surroundings is low. As such an adsorbent 12, for example, a solid amine carbon dioxide adsorbent formed by supporting an amine on a porous material such as silica can be cited.

[0030] The first valve 21 is a switching valve disposed at the connection portion between the carbon dioxide pipeline 103 for recovering carbon dioxide and the module 11. A carbon dioxide recovery pump 63 is disposed on the carbon dioxide pipeline 103. The second valve 22 is a switching valve disposed at the connection portion between the vacuum pipeline 102 provided with the vacuum pump 62 and the module 11. The third valve 23 is a switching valve disposed at the inlet for sucking air or the like into the interior of the module 11. The fourth valve 24 is a switching valve disposed at the connection portion between the adsorption pipeline 101 and the module 11. A fan 61 is disposed on the adsorption pipeline 101.

[0031] The switching of the first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 is all controlled by the control device 90. The first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 are, for example, butterfly valves that are normally open. The adsorbent temperature sensor 27 measures the temperature of the adsorbent 12. The measurement information of the adsorbent temperature sensor 27 is sent to the control device 90.

[0032] The adsorption pipeline 101 branches and is respectively connected to each module 11. The fan 61 is disposed at the part where the branched portions of the adsorption pipeline 101 gather. The fan 61 is driven, thereby generating a gas flow from "suction" to "exhaust" to the module 11 through the adsorption pipeline 101. Thereby, air is supplied into the module 11.

[0033] The vacuum pipeline 102 branches and is respectively connected to each module 11. The vacuum pump 62 is disposed at the part where the branched portions of the vacuum pipeline 102 gather. The vacuum pump 62 is driven to suck the gas inside the module 11 through the vacuum pipeline 102, making the interior of the module 11 in a vacuum state or a state close to vacuum.

[0034] The carbon dioxide pipeline 103 branches and is respectively connected to each module 11. At the part where the branched portions of the carbon dioxide pipeline 103 gather, a carbon dioxide recovery pump 63 is disposed. The carbon dioxide recovery pump 63 exerts an attraction on the carbon dioxide flowing in the carbon dioxide pipeline 103 to store the recovered carbon dioxide in an unillustrated tank for storing carbon dioxide.

[0035] Return Figure 1The heat exchange device 80 will be described. When the desorption process is carried out in each module 11 of the module unit 10, the heat exchange device 80 supplies the heat energy for heating the inside of the module 11 to a specific temperature. In addition, the heat exchange device 80 recovers the heat energy that is not required when the adsorption process is carried out in each module 11.

[0036] The heat exchange device 80 of the present embodiment includes a heat exchanger 81, a cold water tank 82, a cold water pipeline 111, a hot water tank 83, a hot water pipeline 112, and a three-way valve 30.

[0037] The heat exchanger 81 exchanges heat between the heat medium flowing in the cold water pipeline 111 and the heat medium flowing in the hot water pipeline 112. The heat exchanger 81 is, for example, a heat pump. The heat medium is, for example, a liquid such as water. By the heat transfer generated in the heat exchanger 81, the heat medium flowing in the cold water pipeline 111 is cooled, and the heat medium flowing in the hot water pipeline 112 is heated.

[0038] The cold water tank 82 stores the heat medium flowing in the cold water pipeline 111. After the heat medium flowing in the cold water pipeline 111 is stored in the cold water tank 82, it is transported to the heat exchanger 81. In addition, after the heat medium cooled by the heat exchanger 81 returns to the cold water tank 82, it is transported to each module 11 through the cold water pipeline 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 pipeline 111. By driving the heat exchanger circulating water pump 821, the heat medium flowing in the cold water pipeline 111 circulates between the cold water tank 82 and the heat exchanger 81.

[0039] The cold water pipeline 111 branches and is respectively connected to the upstream side and the downstream side of each module 11, thereby connecting the cold water tank 82 and each module 11. In addition, a first cold water circulating water pump 822 and a second cold water circulating water pump 823 are arranged between the cold water tank 82 and each module 11 on the cold water pipeline 111. In addition, a circulating pipeline 824 that returns from the downstream side to the upstream side of the second cold water circulating water pump 823 is arranged on the cold water pipeline 111. A circulating valve 825 is arranged on the circulating pipeline 824.

[0040] The hot water tank 83 stores the heat medium flowing in the hot water pipeline 112. After the heat medium flowing in the hot water pipeline 112 is stored in the hot water tank 83, it is transported to the heat exchanger 81. In addition, after the heat medium heated by the heat exchanger 81 returns to the hot water tank 83, it is transported to each module 11 through the hot water pipeline 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 pipeline 112. By driving the heat exchanger circulating water pump 831, the heat medium flowing in the hot water pipeline 112 circulates between the hot water tank 83 and the heat exchanger 81.

[0041] The hot water pipeline 112 branches and is respectively connected to the upstream side and the downstream side of each module 11, thereby connecting the hot water tank 83 with each module 11. In addition, between the hot water tank 83 and each module 11 on the hot water pipeline 112, a first hot water circulation pump 832 and a second hot water circulation pump 833 are arranged. Further, on the hot water pipeline 112, a circulation pipeline 834 that returns from the downstream side of the second hot water circulation pump 833 to the upstream side is arranged. A circulation valve 835 is arranged on this circulation pipeline 834.

[0042] The three-way valve 30 is connected to the cold water pipeline 111, the hot water pipeline 112, and the module 11. The three-way valve 30 is respectively arranged on the upstream side and the downstream side of the module 11. The three-way valve 30 is configured to be able to switch between a cold water connection state in which the cold water pipeline 111 is connected to the module 11, a hot water connection state in which the hot water pipeline 112 is connected to the module 11, and a blocking state in which the connections of the cold water pipeline 111 and the hot water pipeline 112 to the module 11 are blocked.

[0043] The flow path switching of the three-way valve 30 is controlled by the control device 90. For the module 11, the heat medium is introduced through the three-way valve 30 arranged on the upstream side, and the heat medium returns to the heat exchanger 81 side through the three-way valve 30 arranged on the downstream side.

[0044] Next, the control device 90 will be described. The control device 90 controls the operations of various parts of the carbon dioxide recovery device 1. The control device 90 controls operations such as the driving or stopping of the equipment used for carbon dioxide adsorption or desorption. The control device 90 performs on-off control of the first valve 21, the second valve 22, the third valve 23, and the fourth valve 24 provided in each module 11. In addition, the control device 90 performs driving control of the fan 61, the vacuum pump 62, the carbon dioxide recovery pump 63, the heat exchanger circulation pump 821, the first cold water circulation pump 822, the second cold water circulation pump 823, the heat exchanger circulation pump 831, the first hot water circulation pump 832, the second hot water circulation pump 833, etc., and on-off control of the circulation valve 825 and the circulation valve 835.

[0045] The control device 90 is, for example, a computer having a Central Processing Unit (CPU), a Read Only Memory (ROM), a Random Access Memory (RAM), etc. The control device 90 can be composed of one unit or multiple units.

[0046] <Recovery of Carbon Dioxide>

[0047] Next, the control for carbon dioxide recovery using the control device 90 will be described. The carbon dioxide recovery device 1 removes and recovers carbon dioxide from the air by alternately performing an adsorption process and a desorption process, compressing the desorbed carbon dioxide, and storing it in a tank (not shown). In the adsorption process, the adsorbent 12 in the module 11 adsorbs carbon dioxide in the gas such as the sucked atmosphere. In the desorption process, the carbon dioxide adsorbed by the adsorbent 12 is desorbed. In the present embodiment, the adsorption process and the desorption process are performed with the time of the adsorption process: the time of the desorption process = 3:1.

[0048] The adsorption process is a process in which the adsorbent 12 in the module 11 adsorbs carbon dioxide. 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 the gas containing carbon dioxide (for example, the atmosphere) is sucked through the third valve 23. The sucked gas passes through the adsorbent 12 in the module 11. At this time, the inside of the module 11 is at room temperature (25°C), and the carbon dioxide in the gas is adsorbed on the adsorbent 12. Gases other than carbon dioxide, such as nitrogen or oxygen, are discharged to the outside of the carbon dioxide recovery device 1 through the fourth valve 24 and the adsorption pipeline 101. In addition, in the present embodiment, in this adsorption process, when specific conditions are met, an adsorption heat recovery operation is performed. The adsorption heat recovery operation will be described below.

[0049] The desorption process is a process in which the carbon dioxide of the adsorbent 12 in the module 11 is desorbed. 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 operates to suck the inside of the module 11 and reduce the pressure to a vacuum state or a state close to a vacuum state. At the same time, by means of the heat exchange device 80, a heat medium as a heat source flows in the module 11 to supply heat energy, thereby raising the temperature of the adsorbent 12 in the module 11.

[0050] By controlling the temperature rise of the adsorbent 12, the adsorbent 12 is also heated to a specific temperature (for example, 80°C) sufficient to perform the desorption process, and the carbon dioxide adsorbed by 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 to store the desorbed carbon dioxide in a tank (not shown) through the carbon dioxide pipeline 103. In the present embodiment, each process is controlled so that 12 of the 16 modules 11 perform the adsorption process and the remaining 4 modules perform the desorption process.

[0051] <Adsorption Heat Recovery Operation (Control)>

[0052] In the adsorption process, if carbon dioxide is adsorbed on the adsorbent 12, adsorption heat is generated. This adsorption heat is not utilized in existing carbon dioxide recovery devices. However, if this adsorption heat can be utilized for heating the adsorbent 12 used in the desorption process, the energy required for heating the adsorbent 12 can be suppressed. Therefore, in the carbon dioxide recovery device 1 of the present embodiment, an operation for recovering adsorption heat is performed. The operation for recovering this adsorption heat will be described below.

[0053] Figure 3 It is a schematic diagram showing the heat supply path when adsorption heat recovery is not performed in the adsorption process. Figure 4 It is a schematic diagram showing the heat supply path when adsorption heat recovery is being performed in the adsorption process. Figure 5 It is a diagram for explaining the heat transfer of the module 11 including when adsorption heat recovery is not performed and when adsorption heat recovery is being performed in the adsorption process. In addition, in Figures 3 to 5 the illustration of the remaining module 11 is omitted.

[0054] First, the structure for supplying the heat medium to the module 11 will be described. As Figure 3 and Figure 4 shown, the module 11 includes an inlet-side flow path 33 connected to the inlet where the heat supply medium flows in, and an outlet-side flow path 34 connected to the outlet where the heat supply medium flows out. A three-way valve 30 is arranged at the upstream end of the inlet-side flow path 33, and a three-way valve 30 is also arranged at the downstream end of the outlet-side flow path 34.

[0055] On the inlet-side flow path 33, an inlet temperature sensor 35 is provided. The inlet temperature sensor 35 measures the temperature of the heat medium flowing into the module 11 (hereinafter, also referred to as the inlet temperature), and this measurement information is sent to the control device 90. On the outlet-side flow path 34, an outlet temperature sensor 36 is provided. The outlet temperature sensor 36 measures the temperature of the heat medium flowing out of the module 11 (hereinafter, also referred to as the outlet temperature), and this measurement information is sent to the control device 90. In addition, the carbon dioxide recovery device 1 of the present embodiment further includes a hot water tank temperature sensor 37 and a cold water tank temperature sensor 38. The hot water tank temperature sensor 37 measures the temperature of the hot water tank 83, and this measurement information is sent to the control device 90. The cold water tank temperature sensor 38 measures the temperature of the cold water tank 82, and this measurement information is sent to the control device 90.

[0056] The operation when adsorption heat recovery is not performed in the adsorption process will be described. The state when adsorption heat recovery is not performed in the adsorption process is shown in Figure 3. In the state where adsorption heat recovery is not performed in the adsorption process, it has been cooled to a specific temperature (for example, 20°C) by the cold water pipeline 111 in the previous stage. Therefore, the control device 90 controls the inlet three-way valve 30a and the outlet three-way valve 30b to block both the module 11 and the cold water pipeline 111 and the hot water pipeline 112. In this state, carbon dioxide is adsorbed from the atmosphere introduced by the drive of the fan 61 etc.

[0057] As Figure 5 shown, when the adsorption process starts, adsorption heat is generated. Therefore, the temperature of the adsorbent 12 in the module 11 gradually rises. When the temperature difference ΔT1 between the temperature of the cold water tank 82 obtained from the cold water tank temperature sensor 38 and the temperature of the adsorbent 12 obtained from the adsorbent temperature sensor 27 is above a specific value (the first threshold), the control device 90 controls the inlet three-way valve 30a to connect the cold water pipeline 111 to the inlet side flow path 33, and controls the outlet three-way valve 30b to connect the outlet side flow path 34 to the cold water pipeline 111, thereby starting the adsorption heat recovery ( Figure 4 state). Here, the first threshold can be set appropriately. For example, it can be set to 5°C. In addition, when this adsorption heat recovery is performed, the fan 61 also continues to drive, so that the adsorption of carbon dioxide continues.

[0058] When the adsorption heat recovery starts, the heat medium (cold water) recovers the adsorption heat when passing through the module 11 and is heated. The heated cold water returns to the cold water tank 82. This heated cold water exchanges heat in the heat exchanger 81, so that the recovered adsorption heat is used for heating the hot water. In the initial stage of the adsorption heat recovery, the temperature difference (the water temperature difference ΔT2 at the inlet and outlet of the module) between the inlet temperature measured by the inlet temperature sensor 35 and the outlet temperature measured by the outlet temperature sensor 36 is large, but as the heat recovery progresses, this water temperature difference at the inlet and outlet of the module gradually decreases. At the time point when the water temperature difference ΔT2 at the inlet and outlet of the module is below a specific value (the second threshold), the control device 90 controls the inlet three-way valve 30a and the outlet three-way valve 30b to block both the module 11 and the cold water pipeline 111 and the hot water pipeline 112 ( Figure 3 state). Here, the second threshold can be set appropriately. For example, it can be set to 5°C. After that, after a specific time from the start of adsorption, the adsorption process ends.

[0059] Next, with reference to Figure 6 the switching timing of the start and end of the adsorption heat recovery will be described. Figure 6 is a flowchart showing an example of the operation process of the adsorption heat recovery performed by the carbon dioxide recovery device of the present embodiment.

[0060] If the adsorption process starts, in step S10, the control device 90 determines whether a certain period of time has elapsed since the start of the adsorption process. When a certain period of time has elapsed since the start of the adsorption process, the control device 90 ends the processing of the adsorption process (step S10: Yes). When a certain period of time has not elapsed since the start of the adsorption process, the control device 90 advances the processing of the adsorption process to step S20 (step S10: No).

[0061] In step S20, the control device 90 brings the external gas into contact with the adsorbent 12 to adsorb carbon dioxide. During the adsorption process in this step S20, as Figure 5 shown, the temperature of the adsorbent 12 gradually rises due to the heat of adsorption.

[0062] In step S30, the control device 90 determines whether heat recovery of the heat of adsorption is in progress. When heat recovery is in progress, the control device 90 advances the processing of the adsorption process to step S90 (step S30: Yes). When heat recovery is not in progress, the control device 90 advances the processing of the adsorption process to step S40 (step S30: No).

[0063] In step S40, the control device 90 determines whether the temperature difference ΔT1 between the temperature of the cold water tank 82 obtained from the cold water tank temperature sensor 38 and the temperature of the adsorbent 12 obtained from the adsorbent temperature sensor 27 is equal to or greater than a specific value (first threshold). When ΔT1 is equal to or greater than the specific value (first threshold), the control device 90 advances the processing of the adsorption process to step S50 (step S40: Yes). When ΔT1 is not equal to or greater than the specific value (first threshold), the control device 90 advances the processing of the adsorption process to step S70 (step S40: No).

[0064] In step S50, the control device 90 determines to perform heat recovery of the heat of adsorption. In step S60, the control device 90 controls the inlet three-way valve 30a to connect the cold water line 111 to the inlet side flow path 33, and controls the outlet three-way valve 30b to connect the outlet side flow path 34 to the cold water line 111, thereby forming a flow of cold water for performing heat recovery of the heat of adsorption.

[0065] In step S70, the control device 90 determines not to perform heat recovery of the heat of adsorption. In step S80, the control device 90 controls the inlet three-way valve 30a and the outlet three-way valve 30b so that they are both in the fully closed state, thereby setting a state in which the module 11 is blocked from both the cold water line 111 and the hot water line 112.

[0066] In step S90, the control device 90 determines whether the temperature difference (ΔT2 of the water temperature at the module inlet and outlet) measured by the inlet temperature sensor 35 and the outlet temperature measured by the outlet temperature sensor 36 is equal to or greater than a specific value (second threshold). When ΔT2 is equal to or greater than the specific value (second threshold), the control device 90 advances the processing of the adsorption process to step S50 (step S90: Yes). When ΔT2 is not equal to or greater than the specific value (second threshold), the control device 90 advances the processing of the adsorption process to step S100 (step S90: No).

[0067] In step S100, the control device 90 determines to end the adsorption heat recovery and advances the processing of the adsorption process to step S80.

[0068] In addition, in the operation process exemplified above, in step S90, it is described that the control device 90 determines whether to end the adsorption heat recovery by judging whether the temperature difference ΔT2 between the module inlet and outlet water temperatures is equal to or greater than the second threshold. It is not limited to this operation. For example, the adsorption heat recovery can also be ended when the difference between the temperature of the adsorbent 12 and the temperature of the cooling medium in the cold water tank 82 is less than the third threshold (stopping the flow of the cooling medium to the aforementioned module).

[0069] As described above, in the carbon dioxide recovery device 1 of the present embodiment, in the adsorption process, when the difference between the temperature of the adsorbent 12 and the temperature of the cooling medium in the cold water tank 82 is equal to or greater than the first threshold, the cooling medium is made to flow to the module 11 for heat recovery. Therefore, the adsorption heat that has not been utilized in the past can be effectively utilized, and the heat required for heat exchange in the heat exchanger 81 can be supplemented. As a result, a carbon dioxide recovery device 1 with higher energy efficiency can be provided, and the energy required to raise the temperature of the adsorbent 12 in the desorption process can be suppressed.

[0070] In addition, when the difference between the inlet temperature of the cooling medium at the position where the cooling medium enters the module 11 and the outlet temperature of the cooling medium at the position where the cooling medium leaves the module 11 is less than the second threshold, the carbon dioxide recovery device 1 stops the flow of the cooling medium to the module 11. Thereby, the module cooling performance in the entire carbon dioxide recovery device can be maintained.

[0071] In addition, the carbon dioxide recovery device 1 can also stop the flow of the cooling medium to the module 11 when the difference between the temperature of the adsorbent 12 and the temperature of the cooling medium in the cold water tank 82 is less than the third threshold. Thereby, the module cooling performance in the entire carbon dioxide recovery device can be maintained.

[0072] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments or variations. In addition, the effects described in the above embodiments are only exemplary effects and are not limited to the content described in the above embodiments.

[0073] Reference Numerals

[0074] 1 Carbon dioxide recovery device

[0075] 11 Module

[0076] 12 Adsorption accessory

[0077] 30 Three-way valve

[0078] 61 Fan

[0079] 62 Vacuum pump

[0080] 63 Pump for carbon dioxide recovery

[0081] 80 Heat exchange device

[0082] 81 Heat exchanger

[0083] 82 Cold water tank

[0084] 83 Hot water tank

Claims

1. A carbon dioxide recovery device, comprising: a module having an adsorbent therein and performing an adsorption process and a desorption process, wherein the adsorption process is to attract a gas containing carbon dioxide to the adsorbent to cause the adsorbent to adsorb the carbon dioxide, and the desorption process is to desorb the carbon dioxide from the adsorbent by heating the periphery of the adsorbent under a reduced pressure state; and, a tank for storing a cooling medium for cooling the module; and, in the adsorption process, when the difference between the temperature of the adsorbent and the temperature of the cooling medium in the tank is equal to or greater than a first threshold value, the cooling medium is caused to flow to the module for heat recovery.

2. The carbon dioxide recovery device according to claim 1, wherein when the difference between the inlet temperature at the position where the cooling medium enters the module and the outlet temperature at the position where the cooling medium exits the module is less than a second threshold value, the flow of the cooling medium to the module is stopped.

3. The carbon dioxide recovery device according to claim 1 or 2, wherein when the difference between the temperature of the adsorbent and the temperature of the cooling medium in the tank is less than a third threshold value, the flow of the cooling medium to the module is stopped.

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