Carbon dioxide recovery device and method for operating carbon dioxide recovery device

Abstract

This carbon dioxide recovery device comprises: a gas introduction line into which a carbon-dioxide-containing gas is fed from the outside; a cleaning tower that cleans the gas fed into the gas introduction line by bringing a cleaning liquid into contact with the gas; an absorption tower into which an absorption liquid capable of absorbing the carbon dioxide in the gas is introduced, the absorption tower causing the carbon dioxide in the gas that has passed through the gas cleaning tower to be absorbed by the absorption liquid; a regeneration tower that heats the absorption liquid that has absorbed carbon dioxide, separates the carbon dioxide from the absorption liquid, and regenerates the absorption liquid; and a heating unit that heats the gas fed into the absorption tower.

Description

Carbon dioxide recovery device, operation method of carbon dioxide recovery device

[0001] The present disclosure relates to a carbon dioxide recovery device and an operation method of the carbon dioxide recovery device. This application claims priority based on Japanese Patent Application No. 2025-5313 filed in Japan on January 15, 2025, and the content thereof is incorporated herein by reference.

[0002] It is desired to reduce the emission amount of carbon dioxide contained in the gas from ships, steelworks, etc. For example, Patent Document 1 discloses a configuration including a carbon dioxide recovery device that recovers carbon dioxide contained in the gas (exhaust gas) from a ship.

[0003] Japanese Patent Publication No. 2022-547102

[0004] By the way, in the carbon dioxide recovery device as described above, the gas containing carbon dioxide sent from the internal combustion engine provided on the ship or the blast furnace of the steelworks, etc. to the carbon dioxide recovery device has a temperature range of 50 to 200 °C, which is the general chimney outlet gas temperature, and the configuration of each part is designed.

[0005] However, for example, in ships sailing in sea areas with low seawater temperatures such as the Arctic and Antarctic regions, or steelworks provided in regions where the outside air temperature is below freezing, when the gas is sent to the carbon dioxide recovery device, the temperature of the gas may be in a low temperature range such as below the atmospheric temperature, or even below freezing in cold regions. For example, in a ship, when removing the sulfur content contained in the gas with a desulfurization device before sending the gas to the carbon dioxide recovery device, if low-temperature seawater pumped up from the surrounding sea where the ship floats is used for the desulfurization treatment, the temperature of the gas after the desulfurization treatment will decrease. Also, in a steelworks, etc., when the distance between the blast furnace and the carbon dioxide recovery device is large, the temperature of the gas may decrease before the gas from the blast furnace reaches the carbon dioxide recovery device. In this way, when the temperature of the gas decreases, when absorbing carbon dioxide with an absorption liquid in the carbon dioxide recovery device, the absorption efficiency of carbon dioxide may be significantly reduced.

[0006] This disclosure was made to solve the above-mentioned problems and aims to provide a carbon dioxide capture device and a method for operating the carbon dioxide capture device that can increase the carbon dioxide absorption efficiency even when the gas supplied to the carbon dioxide capture device is at a low temperature.

[0007] To solve the above problems, the carbon dioxide recovery apparatus according to the present disclosure comprises: a gas introduction line into which a gas containing carbon dioxide is supplied from the outside; a washing tower that washes the gas by bringing the gas supplied to the gas introduction line into contact with a washing liquid; an absorption tower into which an absorbent liquid capable of absorbing carbon dioxide in the gas is introduced and the absorbent liquid absorbs the carbon dioxide in the gas that has passed through the gas washing tower; a regeneration tower that heats the absorbent liquid that has absorbed carbon dioxide, separates carbon dioxide from the absorbent liquid, and regenerates the absorbent liquid; and a heating unit that heats the gas supplied to the absorption tower.

[0008] The method for operating a carbon dioxide recovery apparatus according to this disclosure is a method for operating a carbon dioxide recovery apparatus as described above, comprising the steps of: detecting the inlet temperature of the gas supplied through the gas introduction line; and, if the inlet temperature of the gas is within a preset range, heating the gas supplied to the absorption tower in the heating unit.

[0009] According to the carbon dioxide capture device and the operating method of the carbon dioxide capture device described herein, the carbon dioxide absorption efficiency can be increased even when the gas supplied to the carbon dioxide capture device is at a low temperature.

[0010] This is a diagram showing the configuration of a carbon dioxide recovery device according to the first embodiment of this disclosure. This is a flowchart showing the operation method of a carbon dioxide recovery device according to the embodiment of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the second embodiment of this disclosure. This is a diagram showing the hardware configuration of the control device of a carbon dioxide recovery device according to the embodiment of this disclosure. This is a functional block diagram of the control device of a carbon dioxide recovery device according to the embodiment of this disclosure. This is a flowchart showing the operation method of a carbon dioxide recovery device according to the embodiment of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the first modified example of the first and second embodiments of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the second modified example of the first and second embodiments of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the third modified example of the first and second embodiments of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the fourth modified example of the first and second embodiments of this disclosure. This is a diagram showing the configuration of a carbon dioxide recovery device according to the fifth modified example of the first and second embodiments of this disclosure.

[0011] Hereinafter, with reference to the attached drawings, embodiments for implementing the carbon dioxide recovery apparatus and the method of operating the carbon dioxide recovery apparatus according to this disclosure will be described. However, this disclosure is not limited to these embodiments only. <First Embodiment> (Configuration of Carbon Dioxide Recovery Apparatus) Figure 1 is a diagram showing the configuration of a carbon dioxide recovery apparatus according to the first embodiment of this disclosure. The configurations of the carbon dioxide recovery apparatus shown in Figure 1 and each embodiment are schematic diagrams. For the sake of simplifying the schematic diagrams, the flow direction of the low-temperature fluid and the flow direction of the high-temperature fluid that are heat-exchanged as shown in the diagrams for the heat exchangers described later (first heat exchanger 41, third heat exchanger 43, fourth heat exchanger 46, reboiler (second heat exchanger) 48, condenser (fifth heat exchanger) 49) may be opposite to those in reality. The carbon dioxide recovery apparatus 10A shown in Figure 1 is connected to an emission source (not shown) that emits gas containing carbon dioxide, such as a ship or a steel mill. Specifically, in the case of ships, emission sources include, for example, internal combustion engines used as the main engines for propelling the ship, internal combustion engines used in power generation equipment that supplies electricity to the ship, and boilers that generate steam. In the case of steel mills, the emission source is the blast furnace. In such emission sources, the gas produced by burning fuel contains carbon dioxide. In the following explanation, gas containing carbon dioxide will be simply referred to as "gas" as appropriate.

[0012] The carbon dioxide recovery device 10A recovers carbon dioxide contained in the gas from the emission source. The carbon dioxide recovery device 10A comprises a washing tower 11, an absorption tower 12, a regeneration tower 13, a recovery unit 15, and a heating unit 20A.

[0013] The scrubbing tower 11 cleans the gas from the discharge source with a cleaning solution L1. If the discharge source is located on a ship, the cleaning solution L1 can be the water surrounding the ship or fresh water stored in a fresh water tank (not shown) located inside the ship. If the discharge source is located on a steel mill or the like, the cleaning solution L1 can be, for example, seawater, river water, or industrial water.

[0014] One end of a gas introduction line 101 is connected to the lower part of the scrubbing tower 11. The gas introduction line 101 is located at the inlet of the carbon dioxide recovery device 10A, and gas from an external emission source (not shown) is supplied to it. The other end of the gas introduction line 101 is connected to a desulfurization device (not shown) located between the emission source and the scrubbing tower 11. The desulfurization device removes sulfur components such as SO2 contained in the gas. In this embodiment, the gas introduction line 101 is provided with an inlet temperature detection unit 201 for detecting the temperature of the gas introduced into the carbon dioxide recovery device 10A.

[0015] The scrubbing tower 11 comprises a tower body 11a and a nozzle 11b that sprays cleaning liquid L1 from the upper part of the tower body 11a. A cleaning liquid supply line 102 for circulating the cleaning liquid L1 is connected to the scrubbing tower 11. One end of the cleaning liquid supply line 102 is connected to the bottom of the tower body 11a. The other end of the cleaning liquid supply line 102 is connected to the nozzle 11b at the upper part of the tower body 11a.

[0016] A cleaning fluid supply pump 31 and a first heat exchanger 41 are provided in the middle of the cleaning fluid supply line 102. The cleaning fluid supply pump 31 draws the cleaning fluid L1 accumulated at the bottom of the tower body 11a out of the tower body 11a and supplies it to a nozzle at the top of the tower body 11a. The cleaning fluid L1 supplied to the nozzle 11b is sprayed into the tower body 11a from the nozzle 11b and comes into contact (gas-liquid contact) with the gas sent into the tower body 11a. As a result, soot and other particles contained in the gas are captured and washed away by the cleaning fluid L1.

[0017] As will be described in detail later, the first heat exchanger 41 adjusts the temperature of the cleaning liquid L1 by performing heat exchange between the cleaning liquid L1 flowing through the cleaning liquid supply line 102 and the medium flowing through the medium line 107.

[0018] One end of the gas discharge line 103 is connected to the top of the tower body 11a. The gas discharge line 103 sends the gas, which has been cleaned by washing away soot and other debris with a cleaning solution inside the tower body 11a, to the absorption tower 12.

[0019] The absorption tower 12 absorbs carbon dioxide contained in the gas into the absorbent liquid L2. The absorption tower 12 comprises a tower body 12a and nozzles 12b and 12c. Nozzle 12b sprays the absorbent liquid L2 into the tower body 12a, removing carbon dioxide from the gas by bringing it into gas-liquid contact with the gas. Nozzle 12c sprays cleaning water into the tower body 12a, recovering the absorbent liquid L2 sprayed from nozzle 12b contained in the gas by bringing the rising carbon dioxide inside the tower body 12a into contact with the gas from which the carbon dioxide has been removed. The other end of the gas discharge line 103 is connected to the lower part of the tower body 12a. The gas that has passed through the washing tower 11 is sent into the tower body 12a through the gas discharge line 103.

[0020] Nozzle 12b is located in the lower part of the absorption tower 12. Nozzle 12c is located in the upper part of the absorption tower 12. The absorbent liquid L2 is supplied to nozzle 12b from the regeneration tower 13 via a circulation line 106, which will be described later.

[0021] A wash water circulation line 105 is connected to the absorption tower 12 for circulating wash water. One end of the wash water circulation line 105 is connected to the middle section of the tower body 12a. The other end of the wash water circulation line 105 is connected to a nozzle 12c inside the tower body 12a at the top of the tower body 12a. A wash water circulation pump 33 and a third heat exchanger 43 are provided along the wash water circulation line 105. The wash water circulation pump 33 draws wash water from the wash water receiver 12d located in the middle section of the tower body 12a and supplies it to the nozzle 12c at the top of the tower body 12a.

[0022] The absorbent liquid L2 supplied to the nozzle 12b is sprayed into the tower body 12a and comes into contact with the gas sent into the tower body 12a. As a result, the carbon dioxide contained in the gas is absorbed by the absorbent liquid L2 within the tower body 12a of the absorption tower 12.

[0023] A cooling water supply pipe 82A is connected to the third heat exchanger 43. Cooling water is supplied to the third heat exchanger 43 from outside the carbon dioxide recovery device 10A through this cooling water supply pipe 82A. The third heat exchanger 43 performs heat exchange between the cooling water supplied from outside the carbon dioxide recovery device 10A and the cleaning water flowing in the cleaning water circulation line 105. In other words, the third heat exchanger 43 cools the cleaning water circulating in the cleaning water circulation line 105 with the cooling water supplied from outside the carbon dioxide recovery device 10A. The cleaning water cooled by the third heat exchanger 43 is sprayed into the tower body 12a from a nozzle 12c at the top of the tower body 12a.

[0024] One end of the exhaust pipe 12e is connected to the top of the tower body 12a. The exhaust pipe 12e guides the gas that has left the absorption tower 12, in other words, the gas from which the absorbent liquid L2 has been removed by the absorption tower 12, to, for example, an exhaust funnel (not shown) and releases it into the atmosphere.

[0025] The regeneration tower 13 separates gaseous carbon dioxide from the absorbent liquid L2 that absorbed carbon dioxide in the absorption tower 12. The regeneration tower 13 comprises a tower body 13a, a nozzle 13b for spraying the absorbent liquid L2 into the tower body 13a, and a nozzle 13c for spraying the recirculated condensed water. The nozzle 13b is located in the lower part of the tower body 13a. The nozzle 13c is located in the upper part of the tower body 13a.

[0026] A circulation line 106 is provided between the absorption tower 12 and the regeneration tower 13. The circulation line 106 circulates the absorbent liquid L2 between the absorption tower 12 and the regeneration tower 13. The circulation line 106 includes an absorbent liquid supply line 106A, an absorbent liquid discharge line 106B, and a heat exchanger 45.

[0027] One end of the absorbent liquid supply line 106A is connected to the bottom of the tower body 13a of the regeneration tower 13. The other end of the absorbent liquid supply line 106A is connected to the nozzle 12b inside the tower body 12a of the absorption tower 12. A first circulation pump 32A and a fourth heat exchanger 46 are provided along the absorbent liquid supply line 106A. The first circulation pump 32A draws absorbent liquid L2 from the bottom of the tower body 13a of the regeneration tower 13 through the absorbent liquid supply line 106A and supplies it to the nozzle 12b inside the tower body 12a of the absorption tower 12.

[0028] A cooling water supply pipe 82B is connected to the fourth heat exchanger 46. Cooling water is supplied to the fourth heat exchanger 46 from outside the carbon dioxide recovery device 10A via the cooling water supply pipe 82B. The fourth heat exchanger 46 performs heat exchange between the cooling water supplied from outside the carbon dioxide recovery device 10A and the absorbent liquid L2 flowing through the absorbent liquid supply line 106A. In other words, the fourth heat exchanger 46 cools the absorbent liquid L2 supplied to the absorption tower 12 through the absorbent liquid supply line 106A by the cooling water supplied from outside the carbon dioxide recovery device 10A. The absorbent liquid L2 cooled by the fourth heat exchanger 46 is sprayed into the tower body 12a from the nozzle 12b of the absorption tower 12.

[0029] One end of the absorbent liquid discharge line 106B is connected to the bottom of the tower body 12a of the absorption tower 12. The other end of the absorbent liquid discharge line 106B is connected to a nozzle 13b located inside the tower body 13a of the regeneration tower 13. A second circulation pump 32B is installed in the middle of the absorbent liquid discharge line 106B. The second circulation pump 32B draws the absorbent liquid L2 from the bottom of the tower body 12a of the absorption tower 12 through the absorbent liquid discharge line 106B and supplies it to the nozzle 13b of the tower body 13a of the regeneration tower 13.

[0030] The heat exchanger 45 performs heat exchange between the absorbent liquid L2 flowing through the absorbent liquid supply line 106A and the absorbent liquid L2 flowing through the absorbent liquid discharge line 106B. In other words, the heat from the absorbent liquid L2 immediately after carbon dioxide has been separated by the regeneration tower 13 heats the absorbent liquid L2 that has absorbed carbon dioxide before it is introduced into the regeneration tower 13.

[0031] The regeneration tower 13 separates gaseous carbon dioxide from the absorbent liquid L2 that has absorbed carbon dioxide in the absorption tower 12. To this end, the regeneration tower 13 heats the absorbent liquid L2 that has been sent into the regeneration tower 13 from the absorption tower 12 via the absorbent liquid discharge line 106B using the absorbent liquid heating line 108.

[0032] The absorbent liquid heating line 108 is connected to the regeneration tower 13. The absorbent liquid heating line 108 circulates the absorbent liquid L2 between the regeneration tower 13 and the reboiler (second heat exchanger) 48. In other words, the absorbent liquid heating line 108 supplies the absorbent liquid L2 taken from the regeneration tower 13 to the reboiler 48, and also returns the absorbent liquid L2 from the reboiler 48 back into the regeneration tower 13. To put it another way, the reboiler 48 is located in the middle of the absorbent liquid heating line 108.

[0033] A steam supply pipe 81 is connected to the reboiler 48. Steam supplied from a boiler (not shown) located outside the carbon dioxide recovery device 10A is fed into the reboiler 48 via the steam supply pipe 81. The reboiler 48 exchanges heat between the steam supplied through the steam supply pipe 81 and the absorbent liquid L2 flowing through the absorbent liquid heating line 108. In other words, the reboiler 48 heats the absorbent liquid L2 with the heat from the steam.

[0034] The reboiler 48 separates gaseous carbon dioxide from the absorbent liquid L2 by heating it. The absorbent liquid L2 and gaseous carbon dioxide separated in the reboiler 48 are returned to the tower body 13a through the absorbent liquid heating line 108. In this way, the absorbent liquid L2, from which gaseous carbon dioxide has been separated and regenerated, is returned to the absorption tower 12 through the absorbent liquid supply line 106A and reused. Meanwhile, the separated gaseous carbon dioxide is sent to the recovery unit 15 through the gaseous carbon dioxide discharge line 109.

[0035] A condenser (fifth heat exchanger) 49 is installed in the middle of the gaseous carbon dioxide discharge line 109. A cooling water supply pipe 82C is connected to the condenser 49. Cooling water is supplied to the condenser 49 from outside the carbon dioxide recovery device 10A via the cooling water supply pipe 82C. The condenser 49 condenses the water contained in the gaseous carbon dioxide through heat exchange with the cooling water supplied from outside the carbon dioxide recovery device 10A.

[0036] The recovery unit 15 recovers the gaseous carbon dioxide separated in the regeneration tower 13. The recovery unit 15 is a gas-liquid separator that separates the gaseous carbon dioxide sent in via the condenser 49 from the condensed water formed by the condensation of water.

[0037] The gas-liquid separated condensate is returned to the regeneration tower 13 from the bottom of the recovery section 15 through the recirculation line 110. A recirculation pump 112 is provided in the middle of the recirculation line 110 to return the condensate to the regeneration tower 13. The recirculation line 110 is connected to a nozzle 13c located at the top of the regeneration tower 13. The condensate returned to the regeneration tower 13 is sprayed as an absorbent liquid L2 into the tower body 13a from the nozzle 13c of the regeneration tower 13.

[0038] On the other hand, the gaseous carbon dioxide from which water has been removed in the recovery unit 15 is discharged to the outside of the carbon dioxide recovery device 10A through the carbon dioxide discharge pipe 111. The gaseous carbon dioxide discharged through the carbon dioxide discharge pipe 111 is stored, for example, in a carbon dioxide recovery tank (not shown). In this case, the gaseous carbon dioxide may be liquefied using an appropriate carbon dioxide liquefaction device and stored in the carbon dioxide recovery tank.

[0039] In the carbon dioxide recovery system 10A described above, the gas emitted from the emission source (not shown) is washed away in the scrubbing tower 11 and then introduced into the absorption tower 12. In the absorption tower 12, carbon dioxide contained in the gas is absorbed by the absorbent liquid L2. As carbon dioxide is absorbed by the absorbent liquid L2, the gas from which carbon dioxide has been separated is released into the atmosphere. The absorbent liquid L2 that has absorbed carbon dioxide contained in the gas in the absorption tower 12 is sent to the regeneration tower 13 via the circulation line 106. The absorbent liquid L2 that has absorbed carbon dioxide is heated by the reboiler 48 to raise its temperature, and the gaseous carbon dioxide contained in the absorbent liquid L2 is separated. The separated gaseous carbon dioxide is recovered via the recovery section 15. Meanwhile, the absorbent liquid L2 from which carbon dioxide has been separated in the regeneration tower 13 is circulated back to the absorption tower 12 via the circulation line 106.

[0040] (Configuration of the heating section) The heating section 20A heats the gas supplied to the absorption tower 12. The heating section 20A heats the gas when the temperature of the gas supplied to the absorption tower 12 is lower than a preset reference temperature. Here, the reference temperature is preferably set to, for example, 0°C. The reference temperature is not limited to 0°C, but can be set to 5°C, 10°C, etc. as appropriate.

[0041] In this embodiment, the heating unit 20A supplies a heat transfer medium at a higher temperature than the cleaning liquid L1 and the gas sent into the cleaning tower 11 to the first heat exchanger 41, thereby causing heat exchange between the heat transfer medium and the cleaning liquid L1 in the first heat exchanger 41 and heating the cleaning liquid L1.

[0042] In this embodiment, the heating unit 20A includes a heat source 21, a heat transfer medium supply line 122, and a heat transfer medium recovery line 121. The heat source 21 is, for example, an electric heater. The heat source 21 may also be a boiler that generates steam. Alternatively, the heat source 21 may introduce steam generated by a boiler or the like located outside the carbon dioxide recovery device 10A. The heat source 21 heats the heat transfer medium, for example, water, to a temperature higher than the washing liquid L1 and the gas sent into the washing tower 11. An example of the temperature of the heat transfer medium heated by the heat source 21 is 30°C to 50°C. The temperature of the heat transfer medium may be other than those exemplified herein.

[0043] The heat medium supply line 122 and the heat medium recovery line 121 connect the heat source 21 and the medium line 107. The heat medium supply line 122 supplies the heat medium heated by the heat source 21 to the medium line 107. The heat medium supplied to the medium line 107 exchanges heat with the cleaning liquid L1 flowing in the cleaning liquid supply line 102 in the first heat exchanger 41 to heat the cleaning liquid L1. The heat medium recovery line 121 recovers the heat medium that has passed through the first heat exchanger 41 from the medium line 107 and returns it to the heat source 21.

[0044] On the way of the heat medium supply line 122 and the heat medium recovery line 121, on-off valves 122v and 121v are provided. By opening and closing the on-off valves 122v and 121v, the supply of the heat medium from the heating unit 20A to the first heat exchanger 41 can be made intermittent.

[0045] Also, a cold medium supply line 104A and a cold medium discharge line 104B are connected to the medium line 107. The cold medium supply line 104A supplies a cold medium, such as water, at a temperature lower than the cleaning liquid L1 from the outside of the carbon dioxide recovery device 10A to the medium line 107. The cold medium supplied to the medium line 107 exchanges heat with the cleaning liquid L1 flowing in the cleaning liquid supply line 102 in the first heat exchanger 41 to cool the cleaning liquid L1. The cold medium discharge line 104B discharges the cold medium that has passed through the first heat exchanger 41 from the medium line 107.

[0046] On the way of the cold medium supply line 104A and the cold medium discharge line 104B, on-off valves 104v and 104w are provided. By opening and closing the on-off valves 104v and 104w, the supply of the cold medium to the first heat exchanger 41 can be made intermittent.

[0047] In the carbon dioxide recovery device 10A according to this embodiment, the opening and closing valves 104v, 104w, 121v, and 122v are opened and closed based on the temperature of the gas detected by the inlet temperature detection unit 201. In the carbon dioxide recovery device 10A, when the opening and closing valves 104v and 104w are closed and the opening and closing valves 121v and 122v are opened, a heat medium is supplied from the heating unit 20A to the medium line 107. Further, when the opening and closing valves 121v and 122v are closed and the opening and closing valves 104v and 104w are opened, a cold medium is supplied from the cold medium supply line 104A to the medium line 107. Here, the opening and closing of the opening and closing valves 104v, 104w, 121v, and 122v as described above can be performed, for example, by an operator through remote operation from a control room or the like of the carbon dioxide recovery device 10A or manually.

[0048] (Procedure of the operation method of the carbon dioxide recovery device) FIG. 2 is a flowchart showing the flow of the operation method of the carbon dioxide recovery device according to the embodiment of the present disclosure. As shown in FIG. 2, the operation method S10 of the carbon dioxide recovery device according to this embodiment includes a step S11 of detecting the inlet temperature of the gas, a step S12 of confirming whether the inlet temperature is lower than the reference temperature, a step S13 of heating the gas, and a step S14 of cooling the gas.

[0049] In the step S11 of detecting the inlet temperature of the gas, the inlet temperature detection unit 201 detects the temperature of the gas sent through the gas introduction line 101. In the step S12 of confirming whether the inlet temperature is lower than the reference temperature, it is confirmed whether the detected temperature of the gas is lower than a preset reference temperature.

[0050] As a result, if the gas temperature is lower than the reference temperature (step S12: Yes), the process proceeds to step S13. In step S13, where the gas is heated, the heating unit 20A heats the gas sent to the absorption tower 12. In this embodiment, in step S13, the on-off valves 104v and 104w are closed, and the on-off valves 121v and 122v are opened. As a result, a heat transfer medium at a higher temperature than the cleaning liquid L1 is sent to the first heat exchanger 41, heating the cleaning liquid L1. In this way, by heating the cleaning liquid L1 supplied to the scrubbing tower 11, the gas sent to the gas introduction line 101 is cleaned and heated in the scrubbing tower 11.

[0051] Furthermore, if the gas temperature is above the reference temperature in step S12 (step S12: No), the process proceeds to step S14. In step S14, where the gas is cooled, the on-off valves 121v and 122v are closed, and the on-off valves 104v and 104w are opened. As a result, a refrigerant at a lower temperature than the cleaning liquid L1 is sent to the first heat exchanger 41, cooling the cleaning liquid L1. This cleans and cools the gas that comes into contact with the cleaning liquid L1 in the cleaning tower 11.

[0052] (Effects) In the carbon dioxide recovery device 10A with the above configuration, the heating unit 20A heats the gas sent to the absorption tower 12. This makes it possible to raise the temperature of the gas sent to the absorption tower 12 even when the gas sent to the carbon dioxide recovery device 10A is at a low temperature. Therefore, the carbon dioxide absorption efficiency in the absorption tower 12 can be increased. As a result, the carbon dioxide absorption efficiency can be increased even when the gas sent to the carbon dioxide recovery device 10A is at a low temperature.

[0053] Furthermore, the heating unit 20A heats the gas when its temperature is lower than a preset reference temperature. This prevents the gas from being heated more than necessary.

[0054] Furthermore, the heating unit 20A supplies a heat transfer medium at a higher temperature than the cleaning liquid L1 to the first heat exchanger 41 located in the cleaning liquid supply line 102, and heats the cleaning liquid L1 by exchanging heat between the heat transfer medium and the cleaning liquid L1. As a result, in the cleaning tower 11, the gas sent to the gas introduction line 101 comes into contact with the cleaning liquid L1 heated in the first heat exchanger 41, causing its temperature to rise. This increases the carbon dioxide absorption efficiency in the absorption tower 12.

[0055] Furthermore, the first heat exchanger 41 cools the cleaning solution L1 when the gas temperature is above a preset reference temperature. In other words, when the gas temperature in the washing tower 11 is higher than the reference temperature, the washing solution L1 cooled by the first heat exchanger 41 cools the gas, and when the gas temperature is lower than the reference temperature, the washing solution L1 is heated to heat the gas. In this way, the first heat exchanger 41 can be used for both cooling and heating the gas, so there is no need to add a separate heat exchanger for heating the gas. Therefore, even when the gas sent to the carbon dioxide recovery device 10A is at a low temperature, the carbon dioxide absorption efficiency can be increased at a low cost.

[0056] Furthermore, the heating unit 20A is equipped with a heat source 21 for heating the heat transfer medium. By supplying the heat transfer medium heated by the heat source 21 to the first heat exchanger 41, the cleaning liquid L1 is heated, and the temperature of the gas sent to the carbon dioxide recovery device 10A can be increased.

[0057] In the operation method S10 of the carbon dioxide recovery device 10A with the above configuration, the temperature of the gas supplied to the absorption tower 12 can be increased when the gas supplied to the carbon dioxide recovery device 10A is within a preset range. Therefore, even when the gas supplied to the carbon dioxide recovery device 10A is at a low temperature, the carbon dioxide absorption efficiency can be increased.

[0058] <Second Embodiment> Next, a second embodiment of the carbon dioxide recovery apparatus and the method of operating the carbon dioxide recovery apparatus according to the present disclosure will be described. In the second embodiment described below, components common to the first embodiment are denoted by the same reference numerals in the figures and their descriptions are omitted. The second embodiment differs from the first embodiment in that it has a control device 60.

[0059] Figure 3 is a diagram showing the configuration of a carbon dioxide recovery apparatus according to the second embodiment of the present disclosure. As shown in Figure 3, the carbon dioxide recovery apparatus 10B includes a washing tower 11, an absorption tower 12, a regeneration tower 13, a recovery unit 15, a heating unit 20B, and a control device 60 for controlling the heating unit 20B.

[0060] In this embodiment, the carbon dioxide recovery device 10B is equipped with a flow control valve 122w provided in the heat transfer medium supply line 122.

[0061] Furthermore, in this embodiment, the carbon dioxide recovery device 10B includes, in addition to the inlet temperature detection unit 201, a first outlet temperature detection unit 202 and a second outlet temperature detection unit 203. The first outlet temperature detection unit 202 detects the temperature of the gas at the outlet of the scrubbing tower 11 that flows through the gas discharge line 103. The second outlet temperature detection unit 203 detects the temperature of the gas at the outlet of the absorption tower 12 that is discharged through the exhaust pipe 12e.

[0062] Furthermore, the carbon dioxide recovery device 10B in this embodiment is equipped with a replenishment line 210. One end of the replenishment line 210 is connected to the scrubbing tower 11. The other end of the replenishment line 210 is connected to a replenishment water supply line (not shown) through which industrial water flows, for example. The replenishment line 210 can supply the scrubbing tower 11 with industrial water supplied from the replenishment water supply line as replenishment water.

[0063] (Hardware Configuration Diagram) Figure 4 is a diagram showing the hardware configuration of the control device of the carbon dioxide capture device according to the present disclosure. As shown in Figure 4, the control device 60 is a computer equipped with a processor 61 such as a CPU (Central Processing Unit), ROM 62 (Read Only Memory), RAM 63 (Random Access Memory), storage 64, and a signal transmission / reception module 65. The signal transmission / reception module 65 receives signals related to the gas temperature from the inlet temperature detection unit 201, the first outlet temperature detection unit 202, and the second outlet temperature detection unit 203, respectively.

[0064] (Functional Block Diagram) Figure 5 is a functional block diagram of the control device for a carbon dioxide recovery apparatus according to an embodiment of the present disclosure. As shown in Figure 5, the processor 61 of the control device 60 realizes the configurations of the signal input unit 70, the information acquisition unit 71, the valve control unit 72, and the output unit 75 by executing a program pre-stored in a storage device such as a ROM 62 or storage 64. The signal input unit 70 receives signals related to the gas temperature from the inlet temperature detection unit 201, the first outlet temperature detection unit 202, and the second outlet temperature detection unit 203, respectively, via a hardware signal transmission and reception module 65.

[0065] The information acquisition unit 71 acquires the gas temperature values ​​detected by the inlet temperature detection unit 201, the first outlet temperature detection unit 202, and the second outlet temperature detection unit 203, respectively, based on the signals received by the signal input unit 70.

[0066] The valve control unit 72 heats the gas supplied to the absorption tower 12 in the heating unit 20B based on the gas temperature detected by the inlet temperature detection unit 201. The valve control unit 72 heats the gas supplied to the absorption tower 12 in the heating unit 20B if the gas inlet temperature detected by the inlet temperature detection unit 201 is lower than a preset reference temperature.

[0067] Furthermore, the valve control unit 72 controls the opening degree of the flow control valve 122w based on the gas temperature detected by the inlet temperature detection unit 201, the first outlet temperature detection unit 202, and the second outlet temperature detection unit 203. The valve control unit 72 calculates the difference between the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203. The valve control unit 72 controls the opening degree of the flow control valve 122w so that the difference between the gas temperature detected by the first outlet temperature detection unit 202 and the gas temperature detected by the second outlet temperature detection unit 203 falls within a preset range.

[0068] The output unit 75 outputs a control signal to change the opening degree of the flow control valve 122w based on the control of the valve control unit 72.

[0069] (Procedure for operating the carbon dioxide capture device) Figure 6 is a flowchart showing the flow of the operation method of the carbon dioxide capture device according to the present disclosure. In this embodiment, the operation method S20 of the carbon dioxide capture device shown below is realized by the control device 60 sequentially executing processes based on a pre-stored program. As shown in Figure 6, the operation method S20 of the carbon dioxide capture device according to this embodiment includes a step S21 for detecting the gas inlet temperature, a step S22 for confirming whether the inlet temperature is lower than a reference temperature, a step S23 for heating the gas, and a step S24 for cooling the gas.

[0070] In step S21, which detects the gas inlet temperature, the inlet temperature detection unit 201 detects the temperature of the gas being supplied through the gas introduction line 101. The inlet temperature detection unit 201 transmits a signal related to the detected gas temperature to the control device 60. The signal input unit 70 of the control device 60 receives the signal related to the gas temperature from the inlet temperature detection unit 201. The information acquisition unit 71 acquires the value of the gas inlet temperature from the inlet temperature detection unit 201 based on the signal received by the signal input unit 70.

[0071] In step S22, which checks whether the inlet temperature is lower than the reference temperature, the valve control unit 72 checks whether the detected gas inlet temperature is lower than a preset reference temperature, based on the gas inlet temperature obtained from the inlet temperature detection unit 201 by the information acquisition unit 71.

[0072] As a result, in step S22, if the gas temperature is above the reference temperature (step S22: No), the valve control unit 72 closes the on-off valve 121v and the flow rate control valve 122w, and opens the on-off valves 104v and 104w. Then, in the first heat exchanger 41, the cleaning liquid L1 is cooled by exchanging heat between the cleaning liquid L1 and a refrigerant at a lower temperature than the cleaning liquid L1. In this way, the gas in contact with the cleaning liquid L1 in the cleaning tower 11 is cleaned and cooled.

[0073] Furthermore, if the gas temperature is lower than the reference temperature in step S22 (step S22: Yes), the control device 60 starts the process of heating the gas sent to the absorption tower 12 in the heating unit 20B in step S23, which is the procedure shown below. Step S23, which is the step of heating the gas, includes step S231, which sets a target value for the opening degree of the flow control valve 122w; step S232, which sets a target value for the gas temperature at the outlet of the scrubbing tower 11; and step S233, which adjusts the opening degree of the flow control valve 122w.

[0074] In step S231, which sets the target value for the opening degree of the flow control valve 122w, the valve control unit 72 calculates an assumed value for the opening degree of the flow control valve 122w based on the inlet temperature of the gas sent to the scrubbing tower 11 through the gas introduction line 101, as detected by the inlet temperature detection unit 201, and the operating conditions of the carbon dioxide recovery device 10B. The valve control unit 72 sets the calculated assumed value for the opening degree as the target value for the opening degree of the flow control valve 122w. Here, the operating conditions of the carbon dioxide recovery device 10B can be exemplified by the ambient temperature. More specifically, for example, in summer, when the ambient temperature is 20°C or higher, the gas inlet temperature will be 20°C or higher, the same as the ambient temperature, and in such cases, heating of the gas by the heating unit 20B is unnecessary. On the other hand, in winter or other times when the outside temperature is below 0°C, the gas inlet temperature will also be below 0°C, similar to the outside temperature. In such cases, the target value for the opening of the flow control valve 122w is set to, for example, 0% to 50% so that the gas is heated in the heating unit 20B. Furthermore, when the outside temperature is below -10°C and the gas inlet temperature is also below -10°C, the target value for the opening of the flow control valve 122w is set to, for example, 50% to 100% in order to further heat the gas in the heating unit 20B. It goes without saying that the outside temperature, gas inlet temperature, and opening of the flow control valve 122w exemplified here are merely examples and can be changed as appropriate.

[0075] In step S232, which sets the target value for the gas temperature at the outlet of the scrubbing tower 11, the valve control unit 72 acquires the measured value of the gas temperature at the outlet of the absorption tower 12, which is detected by the second outlet temperature detection unit 203. Based on the measured value of the gas temperature at the outlet of the absorption tower 12, the valve control unit 72 sets the target value for the gas temperature at the outlet of the scrubbing tower 11. The valve control unit 72 notes that if the gas temperature at the inlet of the carbon dioxide recovery device 10B is low, the amount of moisture contained in the gas in the absorption tower 12 may be insufficient. If the amount of moisture in the gas in the absorption tower 12 is insufficient, makeup water must be supplied to the absorption tower 12. When supplying makeup water to the absorption tower 12, pure water must be used as makeup water to prevent the contamination of the absorbent liquid L2 in the absorption tower 12 with impurities. However, using pure water as makeup water is costly. In contrast, in this embodiment, the valve control unit 72 sets the target value for the gas temperature at the outlet of the scrubbing tower 11 so that makeup water does not need to be supplied to the absorption tower 12. Specifically, the valve control unit 72 minimizes the difference between the gas temperature at the inlet of the absorption tower 12, i.e., the outlet of the scrubbing tower 11, and the gas temperature at the outlet of the absorption tower 12, so that it is not necessary to supply makeup water into the absorption tower 12. For this reason, in step S232, the valve control unit 72 sets a target value for the gas temperature at the outlet of the scrubbing tower 11, based on the measured value of the gas temperature at the outlet of the absorption tower 12 detected by the second outlet temperature detection unit 203, so that the difference between the gas temperature at the outlet of the absorption tower 12 and the gas temperature at the outlet of the scrubbing tower 11 falls within a preset range. The valve control unit 72 sets the target value for the gas temperature at the outlet of the scrubbing tower 11 to a range such that it is, for example, "measured value of the gas temperature at the outlet of the absorption tower 12 ± 1°C".

[0076] In step S233, which adjusts the opening degree of the flow control valve 122w, the valve control unit 72 adjusts the opening degree of the flow control valve 122w so that the temperature of the gas at the outlet of the scrubbing tower 11 approaches the target value set in step S232, while the absorption tower 12 absorbs carbon dioxide contained in the gas. Specifically, the valve control unit 72 controls the flow control valve 122w to open at the target value of the opening degree set in step S231. As a result, a heat transfer medium at a higher temperature than the cleaning liquid L1 is sent to the first heat exchanger 41 at a flow rate corresponding to the opening degree of the flow control valve 122w, and the cleaning liquid L1 is heated. As a result, the temperature of the gas from the scrubbing tower 11 rises due to contact with the heated cleaning liquid L1 inside the scrubbing tower 11. In step S233, the valve control unit 72 acquires the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203, at predetermined time intervals. The valve control unit 72 calculates the difference between the acquired gas temperature at the outlet of the scrubbing tower 11 and the gas temperature at the outlet of the absorption tower 12. The valve control unit 72 determines whether the calculated difference is within the range set in step S232, and controls the opening degree of the flow rate control valve 122w based on the determination result.

[0077] If the gas temperature at the outlet of the scrubbing tower 11 is lower than the gas temperature at the outlet of the absorption tower 12, and the calculated difference exceeds the range of the target value set in step S232, the valve control unit 72 determines that the gas heating in the scrubbing tower 11 is insufficient and increases the opening of the flow control valve 122w. If the gas temperature at the outlet of the scrubbing tower 11 is higher than the gas temperature at the outlet of the absorption tower 12, and the difference exceeds the range of the target value set in step S232, the valve control unit 72 determines that the gas heating in the scrubbing tower 11 is excessive and decreases the opening of the flow control valve 122w. If the calculated difference is within the range of the target value set in step S232, the valve control unit 72 determines that there is no excess or deficiency in the gas heating in the scrubbing tower 11 and maintains the opening of the flow control valve 122w.

[0078] In step S233, the valve control unit 72 controls the opening degree of the flow control valve 122w based on the difference between the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203. However, it is not limited to this. For example, in step S233, the valve control unit 72 may control the opening degree of the flow control valve 122w based on the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the target value of the gas temperature at the outlet of the scrubbing tower 11 set in step S232. In step S232, the target value of the gas temperature at the outlet of the scrubbing tower 11 is set based on the measured value of the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203. Therefore, the control of the opening degree of the flow control valve 122w in step S233 is substantially performed based on the difference between the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203.

[0079] (Effects) In the carbon dioxide recovery device 10B and the operating method S20 of the carbon dioxide recovery device 10B with the above configuration, the gas sent to the absorption tower 12 is heated in the heating unit 20B, similar to the first embodiment. This makes it possible to raise the temperature of the gas sent to the absorption tower 12 even when the gas sent to the carbon dioxide recovery device 10B is at a low temperature. Therefore, even when the gas sent to the carbon dioxide recovery device 10B is at a low temperature, the carbon dioxide absorption efficiency can be increased.

[0080] Furthermore, the control device 60 controls the heating unit 20B based on the inlet temperature of the gas supplied through the gas introduction line 101. This allows the carbon dioxide absorption efficiency to be automatically increased according to the gas inlet temperature, even when the gas supplied to the carbon dioxide recovery device 10B is at a low temperature.

[0081] Furthermore, the control device 60 heats the gas sent to the absorption tower 12 in the heating unit 20B when the gas inlet temperature is within a preset range. This automatically increases the carbon dioxide absorption efficiency when the gas sent to the carbon dioxide recovery device 10B is at a low temperature.

[0082] Furthermore, the control device 60 controls the heating unit 20B so that the difference between the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203, falls within a preset range. As a result, the difference between the gas temperature at the outlet of the scrubbing tower 11 and the gas temperature at the outlet of the absorption tower 12 becomes smaller, and the inlet temperature of the gas sent to the carbon dioxide recovery device 10B through the gas introduction line 101 becomes relatively lower than the gas temperature at the outlet of the scrubbing tower 11 and the gas temperature at the outlet of the absorption tower 12. When the inlet gas temperature is lower, the amount of water contained in the gas in the scrubbing tower 11 decreases. Therefore, makeup water is supplied to the scrubbing tower 11 through the makeup line 210. In this way, it is possible to suppress the disruption of the mass balance of the absorbent liquid L2 in the absorption tower 12 within the carbon dioxide recovery device 10B system. In this case, when supplying makeup water to the scrubbing tower 11, cheaper industrial water can be used as makeup water compared to pure water, thus suppressing the increase in operating costs of the carbon dioxide capture device 10B.

[0083] (First Modification of the First and Second Embodiments) In the first and second embodiments described above, the heating sections 20A and 20B are equipped with a heat source 21, but the invention is not limited thereto. Figure 7 shows the configuration of a carbon dioxide recovery device according to the first modification of the first and second embodiments of the present disclosure. As shown in Figure 7, in this modification, the heating section 20C of the carbon dioxide recovery device 10C supplies steam that has passed through the second heat exchanger 48 to the first heat exchanger 41 as a heat transfer medium through the heat transfer medium supply line 122C. The steam that has passed through the first heat exchanger 41 is returned to the downstream side of the reboiler 48 through the heat transfer medium recovery line 121C.

[0084] In this carbon dioxide recovery device 10C, the second heat exchanger 48 heats the absorbent liquid L2 supplied to the regeneration tower 13 with steam supplied from the outside. The temperature of the steam that has passed through the second heat exchanger 48 is reduced due to heat exchange with the absorbent liquid L2. In the heating section 20C, the steam that has passed through the second heat exchanger 48 is supplied to the first heat exchanger 41 as a heat transfer medium, thereby effectively utilizing the thermal energy of the steam that has passed through the second heat exchanger 48.

[0085] (Second Modification of the First and Second Embodiments) Figure 8 shows the configuration of a carbon dioxide recovery device according to a second modification of the first and second embodiments of the present disclosure. As shown in Figure 8, in this modification, the heating unit 20D of the carbon dioxide recovery device 10D heats the heat transfer medium supplied to the first heat exchanger 41 with waste heat obtained by cooling the washing water in the third heat exchanger 43. The cooling water that has passed through the third heat exchanger 43 has its temperature increased by cooling the washing water 2 in the third heat exchanger 43. The cooling water that has been heated through the third heat exchanger 43 is supplied to the first heat exchanger 41 as a heat transfer medium through the heat transfer medium supply line 122D. The heat transfer medium (cooling water) that has passed through the first heat exchanger 41 is returned to the downstream side of the third heat exchanger 43 through the heat transfer medium recovery line 121D.

[0086] With this carbon dioxide recovery device 10D, the third heat exchanger 43 cools the wash water that is circulated in the absorption tower 12. The heating unit 20D heats the heat transfer medium using the waste heat obtained by cooling the wash water in the third heat exchanger 43, thereby effectively utilizing the waste heat from the wash water obtained in the third heat exchanger 43.

[0087] (Third Modification of the First and Second Embodiments) Figure 9 shows the configuration of a carbon dioxide recovery device according to a third modification of the first and second embodiments of the present disclosure. As shown in Figure 9, in this modification, the heating section 20E of the carbon dioxide recovery device 10E heats the heat transfer medium supplied to the first heat exchanger 41 with waste heat obtained by cooling the absorbent liquid L2 in the fourth heat exchanger 46. The cooling water that has passed through the fourth heat exchanger 46 has increased in temperature due to the cooling of the absorbent liquid L2 in the fourth heat exchanger 46. The cooling water that has increased in temperature after passing through the fourth heat exchanger 46 is supplied to the first heat exchanger 41 as a heat transfer medium through the heat transfer medium supply line 122E. The heat transfer medium (cooling water) that has passed through the first heat exchanger 41 is returned to the downstream side of the fourth heat exchanger 46 through the heat transfer medium recovery line 121E.

[0088] In this carbon dioxide recovery device 10E, the fourth heat exchanger 46 cools the absorbent liquid L2 that has been regenerated in the regeneration tower 13. The heating unit 20E heats the heat transfer medium using the waste heat obtained by cooling the absorbent liquid L2 in the fourth heat exchanger 46, thereby effectively utilizing the waste heat from the absorbent liquid L2 obtained in the fourth heat exchanger 46.

[0089] (Fourth Modification of the First and Second Embodiments) Figure 10 shows the configuration of a carbon dioxide recovery device according to a fourth modification of the first and second embodiments of the present disclosure. As shown in Figure 10, the heating section 20F of the carbon dioxide recovery device 10F in this modification heats the heat transfer medium supplied to the first heat exchanger 41 with waste heat obtained by cooling gaseous carbon dioxide in the condenser 49. The cooling water that has passed through the condenser 49 has increased in temperature due to the cooling of gaseous carbon dioxide in the condenser 49. The cooling water that has increased in temperature after passing through the condenser 49 is supplied to the first heat exchanger 41 as a heat transfer medium through the heat transfer medium supply line 122F. The heat transfer medium (cooling water) that has passed through the first heat exchanger 41 is returned to the downstream side of the condenser 49 through the heat transfer medium recovery line 121F.

[0090] In this carbon dioxide recovery device 10F, the condenser 49 cools the gaseous carbon dioxide separated in the regeneration tower 13. The heating unit 20F uses the waste heat obtained by cooling the gaseous carbon dioxide in the condenser 49 to heat the heat transfer medium, thereby effectively utilizing the waste heat obtained from the carbon dioxide in the condenser 49.

[0091] (Fifth Modification of the First and Second Embodiments) Figure 11 is a diagram showing the configuration of a carbon dioxide recovery device according to the fifth modification of the first and second embodiments of the present disclosure. As shown in Figure 11, the carbon dioxide recovery device 10G in this modification comprises a desulfurization device 301 and a heat recovery device 302. The desulfurization device 301 removes sulfur contained in the gas from an emission source (not shown) that is fed through the gas introduction line 101. The heat recovery device 302 is provided upstream of the desulfurization device 301 in the gas flow direction and recovers heat from the gas.

[0092] In this modified example, the heating unit 20G heats the heat transfer medium supplied to the first heat exchanger 41 using the heat recovered by the heat recovery device 302. The heat transfer medium, heated by recovering heat from the gas via the heat recovery device 302, is supplied to the first heat exchanger 41 through the heat transfer medium supply line 122G. The heat transfer medium that has passed through the first heat exchanger 41 is returned to the upstream side of the fifth heat exchanger 49 through the heat transfer medium recovery line 121G.

[0093] With such a carbon dioxide recovery device 10G, the heating unit 20G can effectively utilize the thermal energy of the gas by heating the heat transfer medium with heat recovered from the high-temperature gas before desulfurization in the heat recovery device 302.

[0094] (Other Embodiments) Although embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes design changes and the like that do not depart from the gist of the present disclosure. In each of the above embodiments and modifications, the heating of the heat transfer medium in the heating sections 20A to 20G is performed based on the temperature of the gas detected by the inlet temperature detection section 201, but this is not limited to this. The heating of the heat transfer medium in the heating sections 20A to 20G may also be performed based on the ambient temperature or, in the case of a ship, the seawater temperature.

[0095] Furthermore, in each of the above embodiments and modifications, the inlet temperature detection unit 201 for detecting the temperature of the gas introduced into the carbon dioxide recovery devices 10A to 10G is provided in the gas introduction line 101, but this is not limited to this. The inlet temperature detection unit 201 may also be provided in the gas discharge line 103 that sends the gas to the absorption tower 12 via the scrubbing tower 11, and the temperature of the gas may be detected at the inlet of the absorption tower 12.

[0096] Furthermore, in the above embodiments and modifications, the heating sections 20A to 20G are used to heat the cleaning liquid L1 supplied to the cleaning tower 11 in order to heat the gas sent to the absorption tower 12, but the invention is not limited to this. For example, the heating sections 20A to 20G may be used to heat the gas in the gas introduction line 101.

[0097] <Note> The carbon dioxide recovery devices 10A to 10G and the operating methods S10 and S20 of the carbon dioxide recovery devices 10A to 10G described in each embodiment can be understood, for example, as follows.

[0098] (1) The carbon dioxide recovery apparatus 10A to 10G according to the first embodiment comprises a gas introduction line 101 into which a gas containing carbon dioxide is supplied from the outside; a washing tower 11 that washes the gas by bringing a washing liquid L1 into contact with the gas supplied to the gas introduction line 101; an absorption tower 12 into which an absorbent liquid L2 capable of absorbing carbon dioxide in the gas is introduced and the absorbent liquid L2 absorbs the carbon dioxide in the gas that has passed through the washing tower 11; a regeneration tower 13 that heats the absorbent liquid L2 that has absorbed carbon dioxide, separates carbon dioxide from the absorbent liquid L2 and regenerates the absorbent liquid L2; and heating units 20A to 20G that heat the gas supplied to the absorption tower 12.

[0099] The carbon dioxide recovery units 10A to 10G heat the gas sent to the absorption tower 12 in the heating units 20A to 20G. This allows the temperature of the gas sent to the absorption tower 12 to be increased even when the gas sent to the carbon dioxide recovery units 10A to 10G is at a low temperature. Therefore, the carbon dioxide absorption efficiency in the absorption tower 12 can be increased. As a result, the carbon dioxide absorption efficiency can be increased even when the gas sent to the carbon dioxide recovery units 10A to 10G is at a low temperature.

[0100] (2) The carbon dioxide recovery devices 10A to 10G according to the second embodiment are the carbon dioxide recovery devices 10A to 10G of (1), wherein the heating units 20A to 20G heat the gas when the temperature of the gas is lower than a preset reference temperature.

[0101] This prevents the gas from being heated unnecessarily by heating the gas when its temperature is below a preset reference temperature.

[0102] (3) The carbon dioxide recovery apparatus 10A to 10G according to the third embodiment is the carbon dioxide recovery apparatus 10A to 10G of (1) or (2), further comprising a cleaning liquid supply line 102 connected to the cleaning tower 11 and supplying the cleaning liquid L1 to the cleaning tower 11, and a first heat exchanger 41 provided in the cleaning liquid supply line 102, wherein the heating section 20A to 20G supplies the first heat exchanger 41 with a heat transfer medium at a higher temperature than the cleaning liquid L1, and heats the cleaning liquid L1 by exchanging heat between the heat transfer medium and the cleaning liquid L1.

[0103] As a result, the first heat exchanger 41 heats the cleaning liquid L1 supplied to the cleaning tower 11, causing the gas sent to the gas introduction line 101 in the cleaning tower 11 to come into contact with the heated cleaning liquid L1 and its temperature to rise. This increases the carbon dioxide absorption efficiency in the absorption tower 12.

[0104] (4) The carbon dioxide recovery devices 10A to 10G according to the fourth embodiment are the carbon dioxide recovery devices 10A to 10G of (3), wherein the first heat exchanger 41 cools the cleaning liquid L1 by exchanging heat between the cleaning liquid L1 and a refrigerant at a lower temperature than the cleaning liquid L1 when the temperature of the gas is above a preset reference temperature.

[0105] As a result, the first heat exchanger 41 cools the cleaning solution L1 when the gas temperature is above a preset reference temperature. In other words, the scrubbing tower 11 cools the gas with the cleaning solution L1 cooled by the first heat exchanger 41 when the gas temperature is higher than the reference temperature, and heats the cleaning solution L1 to heat the gas when the gas temperature is lower than the reference temperature. In this way, the first heat exchanger 41 can be used for both cooling and heating the gas, so there is no need to add a separate heat exchanger for heating the gas. Therefore, even when the gas supplied to the carbon dioxide recovery devices 10A to 10G is at a low temperature, the carbon dioxide absorption efficiency can be increased at a low cost.

[0106] (5) The carbon dioxide recovery device 10A according to the fifth embodiment is the carbon dioxide recovery device 10A of (3) or (4), wherein the heating unit 20A is equipped with a heat source 21 for heating the heat transfer medium.

[0107] This allows the heat transfer medium heated by the heat source 21 to be supplied to the first heat exchanger 41, thereby heating the cleaning liquid L1 and increasing the temperature of the gas sent to the carbon dioxide recovery device 10A. Examples of the heat source 21 include an electric heater and a boiler.

[0108] (6) The carbon dioxide recovery apparatus 10C according to the sixth embodiment is any one of the carbon dioxide recovery apparatus 10Cs from (3) to (5), further comprising a second heat exchanger 48 that heats the absorbent liquid L2 supplied to the regeneration tower 13 with steam supplied from the outside, and the heating unit 20C supplies the steam that has passed through the second heat exchanger 48 to the first heat exchanger 41 as the heat transfer medium.

[0109] As a result, in the second heat exchanger 48, the absorbent liquid L2 supplied to the regeneration tower 13 is heated by steam supplied from the outside. Due to heat exchange with the absorbent liquid L2, the temperature of the steam that has passed through the second heat exchanger 48 is reduced. In the heating section 20C, the steam that has passed through the second heat exchanger 48 is supplied to the first heat exchanger 41 as a heat transfer medium, thereby effectively utilizing the thermal energy of the steam that has passed through the second heat exchanger 48.

[0110] (7) The carbon dioxide recovery device 10D according to the seventh embodiment is any one of the carbon dioxide recovery devices 10D of (3) to (6), further comprising: a washing water circulation line 105 for circulating washing water used to wash the absorbent liquid L2 in the absorption tower 12 to the upper part of the absorption tower 12; and a third heat exchanger 43 provided in the washing water circulation line 105 for cooling the washing water, wherein the heating unit 20D heats the heat transfer medium supplied to the first heat exchanger 41 with waste heat obtained by cooling the washing water in the third heat exchanger 43.

[0111] As a result, the third heat exchanger 43 cools the cleaning water that is circulated to the upper part of the absorption tower 12. The heating unit 20D uses the waste heat obtained by cooling the cleaning water in the third heat exchanger 43 to heat the heat transfer medium, thereby effectively utilizing the waste heat from the cleaning water obtained in the third heat exchanger 43.

[0112] (8) The carbon dioxide recovery apparatus 10E according to the eighth embodiment is any one of the carbon dioxide recovery apparatus 10Es from (3) to (7), further comprising: an absorbent liquid supply line 106A that supplies the absorbent liquid L2 regenerated in the regeneration tower 13 to the absorption tower 12; and a fourth heat exchanger 46 provided in the absorbent liquid supply line 106A for cooling the absorbent liquid L2, wherein the heating unit 20E heats the heat transfer medium supplied to the first heat exchanger 41 with waste heat obtained by cooling the absorbent liquid L2 in the fourth heat exchanger 46.

[0113] As a result, the fourth heat exchanger 46 cools the absorbent liquid L2 that has been regenerated in the regeneration tower 13. The heating unit 20E heats the heat transfer medium using the waste heat obtained by cooling the absorbent liquid L2 in the fourth heat exchanger 46, thereby effectively utilizing the waste heat from the absorbent liquid L2 obtained in the fourth heat exchanger 46.

[0114] (9) The carbon dioxide recovery device 10F according to the ninth embodiment is any one of the carbon dioxide recovery devices 10F from (3) to (8), further comprising a gaseous carbon dioxide discharge line 109 for discharging gaseous carbon dioxide separated in the regeneration tower 13 from the regeneration tower 13, and a fifth heat exchanger 49 provided in the gaseous carbon dioxide discharge line 109 for cooling the gaseous carbon dioxide, wherein the heating unit 20F heats the heat transfer medium supplied to the first heat exchanger 41 with the waste heat obtained by cooling the gaseous carbon dioxide in the fifth heat exchanger 49.

[0115] As a result, the fifth heat exchanger 49 cools the gaseous carbon dioxide separated in the regeneration tower 13. The heating unit 20F heats the heat transfer medium with the waste heat obtained by cooling the gaseous carbon dioxide in the fifth heat exchanger 49, thereby effectively utilizing the waste heat of the absorbent liquid L2 obtained in the fifth heat exchanger 49.

[0116] (10) The carbon dioxide recovery device 10G according to the tenth embodiment is any one of the carbon dioxide recovery devices 10G of (1) to (9), further comprising a desulfurization device 301 that removes sulfur contained in the gas sent through the gas introduction line 101, and a heat recovery device 302 provided upstream of the desulfurization device 301 in the gas flow direction and recovering heat from the gas, wherein the heating unit 20G heats the heat medium supplied to the first heat exchanger 41 with the heat recovered by the heat recovery device 302.

[0117] As a result, the gas temperature may remain high in the heat recovery unit 302, which is located upstream of the desulfurization unit 301 in the gas flow direction. In such cases, the heat recovered by the heat recovery unit 302 can be used to heat the gas sent to the absorption tower 12, thereby increasing the temperature of the gas sent to the absorption tower 12. Therefore, the carbon dioxide absorption efficiency in the absorption tower 12 can be increased.

[0118] (11) The carbon dioxide recovery device 10B according to the eleventh embodiment is any one of the carbon dioxide recovery devices 10B from (1) to (10), further comprising: an inlet temperature detection unit 201 for detecting the inlet temperature of the gas supplied through the gas introduction line 101; and a control device 60 for controlling the heating unit 20B based on the inlet temperature of the gas detected by the inlet temperature detection unit 201.

[0119] As a result, the control device 60 controls the heating unit 20B based on the inlet temperature of the gas supplied through the gas introduction line 101, thereby automatically increasing the carbon dioxide absorption efficiency according to the gas inlet temperature, even when the gas supplied to the carbon dioxide recovery device 10B is at a low temperature.

[0120] (12) The carbon dioxide recovery device 10B according to the twelfth embodiment is the carbon dioxide recovery device 10B of (11), wherein the control device 60 heats the gas sent to the absorption tower 12 in the heating unit 20B when the gas inlet temperature is lower than a preset reference temperature.

[0121] As a result, when the gas inlet temperature in the control device 60 is within a preset range, the heating unit 20B heats the gas sent to the absorption tower 12, thereby automatically increasing the carbon dioxide absorption efficiency when the gas sent to the carbon dioxide recovery device 10B is at a low temperature.

[0122] (13) A carbon dioxide recovery device 10B according to the 13th embodiment is the carbon dioxide recovery device 10B of (11) or (12), further comprising: a first outlet temperature detection unit 202 for detecting the temperature of the gas at the outlet of the scrubbing tower 11; a second outlet temperature detection unit 203 for detecting the temperature of the gas at the outlet of the absorption tower 12; and a supply line 210 for supplying makeup water to the scrubbing tower 11, wherein the control device 60 controls the heating unit 20B such that the difference between the temperature of the gas detected by the first outlet temperature detection unit 202 and the temperature of the gas detected by the second outlet temperature detection unit 203 is within a preset range.

[0123] As a result, the control device 60 controls the heating unit 20B so that the difference between the gas temperature at the outlet of the scrubbing tower 11, detected by the first outlet temperature detection unit 202, and the gas temperature at the outlet of the absorption tower 12, detected by the second outlet temperature detection unit 203, falls within a preset range. Consequently, the inlet temperature of the gas sent to the carbon dioxide recovery device 10B through the gas introduction line 101 becomes relatively lower than the gas temperature at the outlet of the scrubbing tower 11 and the gas temperature at the outlet of the absorption tower 12. When the gas temperature is lower, the amount of water contained in the gas decreases. Therefore, by supplying makeup water to the scrubbing tower 11 via the replenishment line 210, the lack of water in the scrubbing tower 11 can be compensated for. This prevents the mass balance of the absorbent liquid L2 within the carbon dioxide recovery device 10B system from being disrupted. When supplying makeup water to the scrubbing tower 11, factory water or the like can be used as makeup water, thus suppressing an increase in the operating costs of the carbon dioxide recovery device 10B.

[0124] (14) Operating methods S10, S20 for carbon dioxide recovery devices 10A to 10G according to the 14th embodiment are operating methods S10, S20 for carbon dioxide recovery devices 10A to 10G according to any one of (1) to (13), comprising: steps S11, S21 of detecting the inlet temperature of the gas sent through the gas introduction line 101; and steps S13, S23 of heating the gas sent to the absorption tower 12 in the heating units 20A to 20G when the inlet temperature of the gas is within a preset range.

[0125] In the operating methods S10 and S20 of the carbon dioxide recovery devices 10A to 10G, the temperature of the gas supplied to the absorption tower 12 can be increased when the gas supplied to the carbon dioxide recovery devices 10A to 10G is within a preset range. Therefore, even when the gas supplied to the carbon dioxide recovery devices 10A to 10G is at a low temperature, the carbon dioxide absorption efficiency can be increased.

[0126] According to the carbon dioxide capture device and the operating method of the carbon dioxide capture device described herein, the carbon dioxide absorption efficiency can be increased even when the gas supplied to the carbon dioxide capture device is at a low temperature.

[0127] 10A-10G...Carbon dioxide recovery unit 11...Washing tower 11a...Tower body 11b...Nozzle 12...Absorption tower 12a...Tower body 12b, 12c...Nozzle 12d...Washing water receiver 12e...Exhaust pipe 13...Regeneration tower 13a...Tower body 13b, 13c...Nozzle 15...Recovery section 20A-20G...Heating section 21...Heat source 31...Washing liquid supply pump 32A...First circulation pump 32B...Second circulation pump 33...Absorption liquid circulation pump 41...First heat exchanger 43...Third heat exchanger 45...Heat exchanger 46...Fourth heat exchanger 48...Reboiler (Second heat exchanger) 49...Condenser (Fifth heat exchanger) 60...Control device 61...Processor 62...ROM 63...RAM 64...Storage 65...Signal transmission / reception module 70...Signal input section 71...Information acquisition unit 72...Valve control unit 75...Output unit 81...Steam supply pipe 82A-82C...Cooling water supply pipe 101...Gas introduction line 102...Cleaning liquid supply line 103...Gas discharge line 104A...Refrigerant supply line 104B...Refrigerant discharge line 104v, 104w...On / off valve 105...Cleaning water circulation line 106...Circulation line 106A...Absorbent liquid supply line 106B...Absorbent liquid discharge line 107...Media line 108...Absorbent liquid heating line 109...Gas carbon dioxide discharge line 110...Reflux line 111...Carbon dioxide discharge pipe 112...Reflux pump 121, 121C-121G...Heat transfer medium recovery line 121v...On / off valve 122, 122C-122G...Heat transfer medium supply line 122v...On / off valve 122w...Flow rate control valve 201...Inlet temperature detection unit 202...First outlet temperature detection unit 203...Second outlet temperature detection unit 210...Replenishment line 301...Desulfurization unit 302...Heat recovery unit L1...Washing liquid L2...Absorbent liquid

Claims

1. A carbon dioxide recovery apparatus comprising: a gas introduction line into which a gas containing carbon dioxide is supplied from an external source; a washing tower for washing the gas by bringing the gas supplied to the gas introduction line into contact with a washing liquid; an absorption tower into which an absorbent liquid capable of absorbing carbon dioxide in the gas is introduced and which absorbs the carbon dioxide in the gas that has passed through the gas washing tower; a regeneration tower for heating the absorbent liquid that has absorbed carbon dioxide, separating the carbon dioxide from the absorbent liquid, and regenerating the absorbent liquid; and a heating unit for heating the gas supplied to the absorption tower.

2. The carbon dioxide recovery apparatus according to claim 1, wherein the heating unit heats the gas when the temperature of the gas is lower than a preset reference temperature.

3. The carbon dioxide recovery apparatus according to claim 1 or 2, further comprising: a cleaning liquid supply line connected to the cleaning tower and supplying the cleaning liquid to the cleaning tower; and a first heat exchanger provided in the cleaning liquid supply line, wherein the heating unit supplies a heat transfer medium at a higher temperature than the cleaning liquid to the first heat exchanger and heats the cleaning liquid by exchanging heat between the heat transfer medium and the cleaning liquid.

4. The carbon dioxide recovery apparatus according to claim 3, wherein the first heat exchanger cools the cleaning liquid by exchanging heat between the cleaning liquid and a refrigerant at a lower temperature than the cleaning liquid when the temperature of the gas is above a preset reference temperature.

5. The carbon dioxide recovery apparatus according to claim 3, wherein the heating unit comprises a heat source for heating the heat transfer medium.

6. The carbon dioxide recovery apparatus according to claim 3, further comprising a second heat exchanger that heats the absorbent liquid supplied to the regeneration tower with steam supplied from an external source, wherein the heating unit supplies the steam that has passed through the second heat exchanger to the first heat exchanger as the heat transfer medium.

7. The carbon dioxide recovery apparatus according to claim 3, further comprising: a washing water circulation line for circulating washing water used to wash the absorbent liquid in the absorption tower to the upper part of the absorption tower; and a third heat exchanger provided in the washing water circulation line for cooling the washing water, wherein the heating unit heats the heat transfer medium supplied to the first heat exchanger with waste heat obtained by cooling the washing water in the third heat exchanger.

8. The carbon dioxide recovery apparatus according to claim 3, further comprising: an absorbent liquid supply line for supplying the absorbent liquid regenerated in the regeneration tower to the absorption tower; and a fourth heat exchanger provided in the absorbent liquid supply line for cooling the absorbent liquid, wherein the heating unit heats the heat transfer medium supplied to the first heat exchanger with waste heat obtained by cooling the absorbent liquid in the fourth heat exchanger.

9. The carbon dioxide recovery apparatus according to claim 3, further comprising: a gaseous carbon dioxide discharge line for discharging gaseous carbon dioxide separated in the regeneration tower from the regeneration tower; and a fifth heat exchanger provided in the gaseous carbon dioxide discharge line for cooling the gaseous carbon dioxide, wherein the heating unit heats the heat transfer medium supplied to the first heat exchanger with waste heat obtained by cooling the gaseous carbon dioxide in the fifth heat exchanger.

10. The carbon dioxide recovery apparatus according to claim 3, further comprising: a desulfurization apparatus for removing sulfur contained in the gas sent through the gas introduction line; and a heat recovery apparatus provided upstream of the desulfurization apparatus in the gas flow direction and for recovering heat from the gas, wherein the heating section heats the heat medium supplied to the first heat exchanger with the heat recovered by the heat recovery apparatus.

11. The carbon dioxide recovery apparatus according to claim 1 or 2, further comprising: an inlet temperature detection unit for detecting the inlet temperature of the gas supplied through the gas introduction line; and a control device for controlling the heating unit based on the inlet temperature of the gas detected by the inlet temperature detection unit.

12. The carbon dioxide recovery apparatus according to claim 11, wherein the control device heats the gas sent to the absorption tower in the heating unit when the gas inlet temperature is lower than a preset reference temperature.

13. The carbon dioxide recovery apparatus according to claim 11, further comprising: a first outlet temperature detection unit for detecting the temperature of the gas at the outlet of the scrubbing tower; a second outlet temperature detection unit for detecting the temperature of the gas at the outlet of the absorption tower; and a supply line for supplying makeup water to the scrubbing tower, wherein the control device controls the heating unit so that the difference between the temperature of the gas detected by the first outlet temperature detection unit and the temperature of the gas detected by the second outlet temperature detection unit falls within a preset range.

14. A method for operating a carbon dioxide recovery apparatus according to claim 1 or 2, comprising the steps of: detecting the inlet temperature of the gas supplied through the gas introduction line; and heating the gas supplied to the absorption tower in the heating unit when the inlet temperature of the gas is within a preset range.

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