Acidic gas recovery system

Abstract

This acidic gas recovery system comprises: a cooling tower into which a gas to be treated containing an acidic gas is introduced and which cools the gas to be treated; an inlet adsorption device that brings the gas to be treated cooled by the cooling tower into contact with an activated carbon to remove hydrocarbons remaining in the gas to be treated; an absorption tower that discharges an absorption liquid that has absorbed the acidic gas and an absorption tower discharge gas containing the gas to be treated from which the acidic gas has been removed; and a regeneration tower that discharges the absorption liquid from which the acidic gas has dissipated and a regeneration tower discharge gas containing the acidic gas.

Description

Acid Gas Recovery System

[0001] This disclosure relates to an acid gas recovery system. This application claims priority to U.S. Patent Application No. 18 / 816,592, filed August 27, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, from the perspective of carbon neutrality, carbon dioxide (CO ２ ) concentration has been attracting attention. From the viewpoint of reducing the concentration of carbon dioxide in the atmosphere, carbon dioxide capture systems that capture carbon dioxide from flue gas are known. In carbon dioxide capture systems, an absorption liquid is circulated between a regeneration tower and an absorption tower to capture carbon dioxide from flue gas.

[0003] For example, Patent Document 1 discloses a carbon dioxide recovery device (CO 2 recovery device) capable of filtering out solid matter such as soot and fly ash remaining in an absorption solution for removing carbon dioxide from exhaust gas. ２ This carbon dioxide capture system is a CO ２ an absorption tower that absorbs carbon dioxide with an absorption liquid; ２ It is equipped with a regeneration tower that removes carbon dioxide from the absorption liquid and returns it to the absorption tower.

[0004] Patent No. 6216259

[0005] Incidentally, in a system for recovering acidic gases such as the carbon dioxide recovery system described above, impurities contained in the gas to be treated, such as exhaust gas, may include hydrocarbons with high boiling points, including trace amounts of polycyclic aromatic hydrocarbons (PAHs). When such hydrocarbons are incorporated into a liquid, they circulate within the recovery system together with the absorption liquid. As a result, the hydrocarbons accumulate in the circulating absorption liquid. When hydrocarbons accumulate in the absorption liquid, they solidify in the absorption liquid and precipitate during the circulation process, which may clog pipes and equipment. Therefore, it is desirable to suppress the incorporation of hydrocarbons into the absorption liquid. In addition, when CO ２ When an amine solution or the like is used as the absorption liquid, degradation products that are generated over the course of operation accumulate in the recovery system, or some of them are converted into CO ２VOCs are released into the atmosphere from the absorption tower of the recovery system, and are released from the regeneration tower to produce CO ２ There is a problem of reducing purity.

[0006] The present disclosure provides an acid gas recovery system that can efficiently suppress the incorporation of hydrocarbons into the absorption liquid and the accumulation of degradation products in the absorption liquid.

[0007] The acidic gas recovery system according to the present disclosure includes a cooling tower into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered and which cools the gas to be treated; an inlet adsorption device that brings the gas to be treated cooled in the cooling tower into contact with activated carbon to remove hydrocarbons remaining in the gas to be treated; an absorption tower into which the gas to be treated from which the hydrocarbons have been removed in the inlet adsorption device is introduced and brings the gas to be treated into contact with an absorption liquid, and discharges the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; and a regeneration tower that strips the acidic gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas.

[0008] Another disclosed acidic gas recovery system includes an absorption tower into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered, contacting the gas to be treated with an absorption liquid, and discharging the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; a regeneration tower that strips the acidic gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas; a gas-liquid separator that separates moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower, discharges a separated exhaust gas from which the moisture has been separated, and supplies the separated moisture to the regeneration tower as drain water; a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower; and a drain water adsorption device that contacts the drain water supplied to the regeneration tower from at least one of the gas-liquid separator and the dehydration device with activated carbon to remove the hydrocarbons remaining in the drain water.

[0009] Another disclosed acidic gas recovery system includes an absorption tower into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered, contacting the gas to be treated with an absorption liquid, and discharging the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; a regeneration tower that strips the acidic gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas; a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower; and an outlet adsorption device that contacts the regeneration tower exhaust gas from which moisture has been removed by the dehydration device with activated carbon to remove the hydrocarbons remaining in the regeneration tower exhaust gas.

[0010] According to the acid gas recovery system of the present disclosure, it is possible to efficiently suppress the incorporation of hydrocarbons into the absorption liquid and the accumulation of degradation products in the absorption liquid.

[0011] Fig. 1 is a schematic diagram showing a carbon dioxide capture system according to a first embodiment; Fig. 2 is a schematic diagram showing a carbon dioxide capture system according to a second embodiment; Fig. 3 is a schematic diagram showing a carbon dioxide capture system according to a third embodiment; Fig. 4 is a schematic diagram showing a carbon dioxide capture system according to a modified example;

[0012] Hereinafter, an embodiment of an acid gas recovery system according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to this embodiment.

[0013] First Embodiment (Carbon Dioxide Capture System) A carbon dioxide capture system (acid gas capture system) 1 is a facility that captures acid gas from a gas to be treated from a gas source (not shown). As shown in FIG. 1 , the carbon dioxide capture system 1 of this embodiment separates and captures carbon dioxide contained in the gas to be treated using an absorbent, and is capable of supplying the captured carbon dioxide to another device. Examples of gas sources include waste incinerators, coal- or natural gas-fired power plants, gas turbines, gas engines, cement plants, steel plants, glass melting plants, and ethanol production plants. The gas to be treated from these gas sources contains a gas to be captured, ash, heavy metals, hydrocarbons, and the like. The gas to be captured includes, in addition to carbon dioxide (CO), nitrogen oxides (NOx) such as nitric oxide (NO), sulfur oxides (SOx) such as sulfur dioxide (SO), and acid gases such as hydrogen sulfide (HS). In this embodiment, carbon dioxide will be described as an example of a gas to be captured. The gas generation source may also be a facility that is external to the carbon dioxide capture system 1 and sends atmospheric air to the carbon dioxide capture system 1. In other words, the carbon dioxide capture system 1 treats exhaust gases emitted from various facilities and atmospheric air as gases to be treated.

[0014] The absorption liquid is preferably a high-concentration liquid in order to improve the absorption rate of acidic gases and reduce the regeneration energy. For example, when absorbing carbon dioxide, the absorption liquid is preferably an amine aqueous solution or a non-aqueous amine liquid in which a physical absorption solvent is used instead of water. Specific examples of the amine absorption liquid that can be used include alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA), and diglycolamine (DGA). Hindered amines can also be used. Aqueous solutions of these alone or a mixture of two or more of these can also be used.

[0015] The carbon dioxide capture system 1 of this embodiment includes a supply line L1, a cooling tower 2, a supply cooling circulation line L2, a cooler discharge line L3, an inlet adsorption device 3, an inlet adsorption line L4, an absorption tower 4, an absorption tower discharge line L5, a rich line L6, a regeneration tower 5, a lean line L8, a regeneration tower discharge gas line L7, an absorption liquid heat exchanger 6, a lean liquid adsorption supply line L9, a lean liquid adsorption device 7, a lean liquid adsorption discharge line L10, a gas-liquid separator 8, a drain return line L11, a separated discharge gas line L12, a first outlet adsorption device 9, and a first removal line L13.

[0016] The supply line L1 sends a portion of the gas to be treated that contains carbon dioxide and is generated in the gas generation source to the cooling tower 2. The supply line L1 is a pipe that connects the gas generation source and the cooling tower 2.

[0017] (Cooling Tower) A gas to be treated containing carbon dioxide as a gas to be recovered is introduced into the cooling tower 2 via a supply line L1. In addition, cooled water (e.g., drain water) is introduced into the cooling tower 2 via a supply cooling circulation line L2. The cooling tower 2 cools the introduced gas to be treated by bringing the gas into contact with the water. The gas to be treated cooled in the cooling tower 2 is sent to a cooler discharge line L3. In the cooling tower 2, the gas to be treated, which has a temperature of 100°C to 200°C, is cooled to 40°C to 50°C. In addition, the cooling tower 2 sends the water heated by cooling the gas to be treated to the supply cooling circulation line L2.

[0018] The supply cooling circulation line L2 circulates the water heated in the cooling tower 2, cooling it and sending it back to the cooling tower 2. The supply cooling circulation line L2 has a supply circulation pump 21 and a supply circulation cooler 22 along the way. The supply circulation pump 21 pressurizes the water discharged from the cooling tower 2 and sends it to the cooling tower 2 via the supply circulation cooler 22. The supply circulation cooler 22 cools the supplied water by exchanging heat with a cooling liquid.

[0019] The cooler discharge line L3 sends the gas to be treated that has been cooled in the cooling tower 2 to the inlet adsorption device 3 via the supply blower 31. The cooler discharge line L3 is a pipe that connects the cooling tower 2 and the inlet adsorption device 3.

[0020] The supply blower 31 is disposed midway along the cooler discharge line L3. The supply blower 31 increases the flow rate of the gas to be treated that has been cooled in the cooling tower 2 and supplies it to the inlet adsorption device 3. Specifically, the supply blower 31 is capable of increasing the pressure of the gas to be treated flowing through the cooler discharge line L3. The supply blower 31 increases the pressure of the gas to be treated that flows through the cooler discharge line L3, thereby increasing the temperature of the gas to be treated that is introduced into the inlet adsorption device 3 and the absorber. The supply blower 31 is capable of changing the pressure increase rate of the gas to be treated.

[0021] (Inlet Adsorption Device) The inlet adsorption device 3 brings the gas to be treated, which has been cooled in the cooling tower 2, into contact with activated carbon to remove hydrocarbons remaining in the gas to be treated. The inlet adsorption device 3 of this embodiment is capable of removing high-boiling-point hydrocarbons, including trace amounts of polycyclic aromatic hydrocarbons (PAHs), from the gas to be treated by adsorbing them onto activated carbon. The cooled and pressurized gas to be treated is introduced into the inlet adsorption device 3 via the cooler discharge line L3. The inlet adsorption device 3 sends the gas to be treated, from which the hydrocarbons have been removed, to the inlet adsorption line L4. The inlet adsorption device 3 is, for example, a vertically extending tank filled with activated carbon, and the gas to be treated can flow through the tank.

[0022] The inlet adsorption line L4 sends the gas to be treated, from which hydrocarbons have been removed by the inlet adsorption device 3, to the absorption tower 4. The inlet adsorption line L4 is a pipe that connects the inlet adsorption device 3 and the absorption tower 4.

[0023] (Absorption Tower) The absorption tower 4 is introduced with the target gas containing carbon dioxide via the inlet adsorption line L4. The target gas from which hydrocarbons have been removed in the inlet adsorption device 3 is introduced into the absorption tower 4. The absorption tower 4 removes carbon dioxide from the target gas by bringing the target gas into contact with an absorption liquid. The absorption tower 4 separately discharges the absorption liquid that has absorbed carbon dioxide and the absorption tower exhaust gas containing the target gas from which carbon dioxide has been removed. The absorption tower 4 is also introduced with the absorption liquid from which carbon dioxide has been stripped in the regeneration tower 5 via the lean line L8. The absorption tower 4 of this embodiment has a recovery section 41, a water washing section 42, and an absorption tower circulation line L43.

[0024] The recovery unit 41 brings the gas to be treated into contact with the absorbing liquid. The recovery unit 41 causes the absorbing liquid to recover carbon dioxide. The recovery unit 41 is provided with a nozzle (not shown) that sprays the absorbing liquid vertically downward. As a result, in the recovery unit 41, the gas to be treated flowing vertically upward and the absorbing liquid flowing vertically downward come into countercurrent contact, and the carbon dioxide in the gas to be treated is absorbed by the absorbing liquid.

[0025] The water washing section 42 brings the decarbonated gas, which has come into contact with the absorption liquid in the recovery section 41, into contact with wash water. The water washing section 42 recovers the absorption liquid components entrained in the decarbonated gas. The water washing section 42 is disposed vertically above the recovery section 41. A nozzle (not shown) that sprays wash water vertically downward is disposed in the water washing section 42. As a result, in the water washing section 42, the decarbonated gas flowing vertically upward and the wash water flowing vertically downward come into countercurrent contact. As a result, the water washing section 42 cools the decarbonated gas and recovers the absorption liquid components with the wash water.

[0026] The absorber circulation line L43 circulates condensed water containing the wash water and absorption liquid used in the water washing section 42 so as to return it to the nozzles of the water washing section. The absorber circulation line L43 recovers condensed water generated in the water washing section 42 from between the water washing section 42 and the recovery section 41 in the vertical direction. An absorber circulation pump 431 and an absorber circulation heat exchanger 432 are arranged on the absorber circulation line L43. The absorber circulation pump 431 pressurizes the condensed water and sends it to the nozzles of the water washing section 42. The absorber circulation heat exchanger 432 cools the supplied condensed water and sends it to the nozzles of the water washing section 42.

[0027] The absorber discharge line L5 discharges the absorber exhaust gas discharged from the absorber 4 to the outside. In other words, the absorber discharge line L5 discharges the absorber exhaust gas to the outside of the carbon dioxide capture system 1. The absorber discharge line L5 is connected to the top of the absorber 4.

[0028] The rich line L6 supplies the absorption liquid that has absorbed carbon dioxide from the absorption tower 4 to the regeneration tower 5. Here, the absorption liquid that is discharged from the absorption tower 4 and flows through the rich line L6 is referred to as the rich liquid. The rich liquid is the absorption liquid with a high concentration of carbon dioxide after absorbing carbon dioxide in the absorption tower 4. The rich line L6 connects the bottom of the absorption tower 4 with the top of the regeneration tower 5. A rich pump 61 is arranged in the rich line L6. The rich pump 61 pressurizes the rich liquid and sends it to the regeneration tower 5 via the absorption liquid heat exchanger 6.

[0029] (Regeneration Tower) Rich liquid is introduced into the regeneration tower 5 via a rich line L6. The regeneration tower 5 strips carbon dioxide from the rich liquid, which is the absorption liquid discharged from the absorption tower 4. The regeneration tower 5 heats the rich liquid using a reboiler 51. As a result, in the regeneration tower 5, most of the carbon dioxide is stripped from the rich liquid together with steam, and the carbon dioxide is separated from the rich liquid. High-temperature steam is supplied to the reboiler 51. The reboiler 51 heats the absorption liquid by performing heat exchange between the steam and the absorption liquid. The regeneration tower 5 separately discharges the absorption liquid from which carbon dioxide has been stripped and the regeneration tower exhaust gas containing carbon dioxide. The regeneration tower 5 sends the absorption liquid from which carbon dioxide has been stripped to a lean line L8. The regeneration tower 5 sends the regeneration tower exhaust gas containing carbon dioxide to a regeneration tower exhaust gas line L7.

[0030] The lean line L8 supplies the absorption liquid from which carbon dioxide has been stripped to the absorption tower 4 from the regeneration tower 5. Here, the absorption liquid discharged from the regeneration tower 5 and flowing through the lean line L8 is referred to as the lean liquid. The lean liquid is the absorption liquid with a low carbon dioxide concentration after carbon dioxide has been stripped in the regeneration tower 5. In other words, the lean liquid has a lower carbon dioxide concentration than the rich liquid. The lean line L8 connects the bottom of the regeneration tower 5 to the recovery section 41 of the absorption tower 4. A lean pump 81 and a lean cooler 82 are arranged in the lean line L8. The lean pump 81 pressurizes the lean liquid and sends it to the absorption tower 4 via the absorption liquid heat exchanger 6. The lean cooler 82 further cools the absorption liquid cooled in the absorption liquid heat exchanger 6 and sends it to the absorption tower 4.

[0031] (Absorbing Liquid Heat Exchanger) The absorbing liquid heat exchanger 6 exchanges heat between the rich liquid flowing in the rich line L6 and the lean liquid flowing in the lean line L8. As a result, the absorbing liquid heat exchanger 6 heats the rich liquid that flows through the rich line L6 in a state where the pressure has been increased by the rich pump 61 so as to travel from the absorption tower 4 to the regeneration tower 5. At the same time, the absorbing liquid heat exchanger 6 cools the lean liquid that flows through the lean line L8 in a state where the pressure has been increased by the lean pump 81 so as to travel from the regeneration tower 5 to the absorption tower 4.

[0032] The lean liquid adsorption supply line L9 sends a portion of the lean liquid cooled in the absorption liquid heat exchanger 6 to the lean liquid adsorption device 7. The lean liquid adsorption supply line L9 is connected to the lean line L8 between the absorption liquid heat exchanger 6 and the absorption tower 4. The lean liquid adsorption supply line L9 is a pipe that connects the lean line L8 and the lean liquid adsorption device 7.

[0033] The lean liquid adsorption device 7 brings a portion of the lean liquid cooled in the absorption liquid heat exchanger 6 into contact with activated carbon to remove hydrocarbons remaining in the lean liquid. The lean liquid adsorption device 7 of this embodiment is configured to adsorb high-boiling point hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), onto activated carbon, thereby removing them from the lean liquid. A portion of the lean liquid cooled in the absorption liquid heat exchanger 6 is introduced into the lean liquid adsorption device 7 via a lean liquid adsorption supply line L9. The lean liquid adsorption device 7 sends the lean liquid, from which the hydrocarbons have been removed, to a lean liquid adsorption discharge line L10. The lean liquid adsorption device 7 is configured, for example, as a vertically extending tank filled with activated carbon, through which the lean liquid can flow.

[0034] The lean liquid adsorption discharge line L10 sends the lean liquid, from which hydrocarbons have been removed in the lean liquid adsorption device 7, back to the lean line L8. The lean liquid adsorption discharge line L10 is connected to the lean line L8 between the junction of the lean liquid adsorption supply line L9 and the lean line L8 and the absorber 4. Therefore, the lean liquid adsorption discharge line L10 returns a portion of the lean liquid removed from the lean line L8 by the lean liquid adsorption supply line L9 to the lean line L8. The lean liquid adsorption discharge line L10 is a pipe connecting the lean line L8 and the lean liquid adsorption device 7.

[0035] The regeneration tower exhaust gas line L7 supplies the regeneration tower exhaust gas discharged from the regeneration tower 5 to the gas-liquid separator 8. The regeneration tower exhaust gas line L7 is connected to the top of the regeneration tower 5. The regeneration tower exhaust gas line L7 is a pipe that connects the regeneration tower 5 and the gas-liquid separator 8. The regeneration tower exhaust gas line L7 has a regeneration tower exhaust gas condenser 71 midway. The regeneration tower exhaust gas condenser 71 cools the regeneration tower exhaust gas discharged from the regeneration tower 5 to condense the moisture into liquid.

[0036] (Gas-liquid separator) The gas-liquid separator 8 separates moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower 5. The gas-liquid separator 8 discharges the separated exhaust gas from which moisture has been separated, and supplies the separated moisture to the regeneration tower 5 as separated drain water. In other words, the separated drain water is drain water discharged from the gas-liquid separator 8. The gas-liquid separator 8 of this embodiment recovers moisture generated by condensation in the regeneration tower exhaust gas condenser 71. The moisture recovered by the gas-liquid separator 8 is discharged as separated drain water to the drain return line L11. The gas-liquid separator 8 discharges the separated exhaust gas to the separated exhaust gas line L12.

[0037] The drain return line L11 supplies the separated drain water discharged from the gas-liquid separator 8 to the regeneration tower 5. The drain return line L11 is a pipe connecting the gas-liquid separator 8 and the regeneration tower 5. A drain return pump 111 is arranged in the drain return line L11. The drain return pump 111 pressurizes the separated drain water and sends it to the regeneration tower 5.

[0038] The separated exhaust gas line L12 supplies the separated exhaust gas discharged from the gas-liquid separator 8 to the first outlet adsorption device 9. The separated exhaust gas line L12 is a pipe that connects the gas-liquid separator 8 and the first outlet adsorption device 9.

[0039] (First Outlet Adsorption Device) The first outlet adsorption device 9 contacts the regeneration tower exhaust gas discharged from the regeneration tower 5 with activated carbon to remove hydrocarbons remaining in the regeneration tower exhaust gas. The first outlet adsorption device 9 of this embodiment contacts the separated exhaust gas from which water has been separated in the gas-liquid separator 8 with activated carbon to remove hydrocarbons remaining in the separated exhaust gas. The first outlet adsorption device 9 adsorbs high-boiling-point hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), onto the activated carbon, enabling them to be removed from the separated exhaust gas. The separated exhaust gas is introduced into the first outlet adsorption device 9 via the separated exhaust gas line L12. The first outlet adsorption device 9 sends the separated exhaust gas from which the hydrocarbons have been removed to the first removal line L13. The first outlet adsorption device 9 is, for example, a vertically extending tank filled with activated carbon, allowing the separated exhaust gas to flow through the tank.

[0040] The first removal line L13 discharges the separated exhaust gas from which hydrocarbons have been removed from the first outlet adsorption device 9. The first removal line L13 of this embodiment transfers the separated exhaust gas from which hydrocarbons have been removed to, for example, an external destination depending on the intended use. The separated exhaust gas from which hydrocarbons have been removed and discharged from the first removal line L13 is transferred to a state depending on the intended use, for example, and is stored in a tank, a tanker, a pipeline, inside an oil field, an aquifer, or the like.

[0041] (Effects) In the carbon dioxide capture system 1 configured as described above, the target gas cooled in the cooling tower 2 is supplied to the inlet adsorption device 3 via the cooler discharge line L3, where it comes into contact with activated carbon and hydrocarbons are removed. That is, the inlet adsorption device 3 removes hydrocarbons from the target gas before it is supplied to the absorption tower 4. This prevents hydrocarbons, including polycyclic aromatic hydrocarbons, from flowing into the absorption tower 4. Furthermore, the inlet adsorption device 3 removes hydrocarbons from the target gas after it has been cooled in the cooling tower 2. The target gas after it has been cooled in the cooling tower 2 not only has a lower gas temperature, but also has a lower moisture concentration and impurity concentration in accordance with the lowered gas temperature. Because activated carbon also adsorbs water, it has the disadvantage that its adsorption performance for hydrocarbons decreases when the moisture concentration is high. In the inlet adsorption device 3 configured as described above, the lowered moisture concentration improves the adsorption performance of hydrocarbons by the activated carbon in the target gas after it has been cooled, compared to the target gas before it was cooled. As a result, the activated carbon is efficiently used to adsorb hydrocarbons, and the incorporation of hydrocarbons into the absorption liquid can be efficiently suppressed. In addition, by arranging the inlet adsorption device 3 downstream of the supply blower 31, the relative humidity in the moisture-saturated exhaust gas from the cooling tower 2 can be reduced, and the amount of moisture condensing in the activated carbon pores can be reduced, thereby improving the adsorption performance of hydrocarbons.

[0042] Furthermore, when hydrocarbons flow into the absorption tower 4, the hydrocarbons mixed in the absorption liquid solidify in the absorption liquid as it flows. As a result, the hydrocarbons may precipitate in flow paths such as the rich line L6 and the lean line L8 and in devices such as the absorption liquid heat exchanger 6, potentially causing a decrease in the performance of various devices. However, by suppressing the mixing of hydrocarbons into the absorption liquid, it is possible to reduce the accumulation of hydrocarbons in the absorption liquid. This allows the operating time of the carbon dioxide capture system 1 including the absorption tower 4 to be extended.

[0043] In particular, in this embodiment, the high-temperature gas to be treated is cooled to 40°C to 50°C in the cooling tower 2. The lower the temperature, the higher the efficiency with which activated carbon adsorbs hydrocarbons from the gas to be treated. Therefore, by supplying the gas to be treated that has been cooled to 40°C to 50°C in the cooling tower 2 to the inlet adsorption device 3, the adsorption performance of the activated carbon can be further improved. This makes it possible to more efficiently suppress the incorporation of hydrocarbons into the absorption liquid.

[0044] Furthermore, the gas temperature of the gas to be treated after being cooled is lower than that of the gas to be treated before being cooled, and the gas volume (flow rate) is also reduced. Therefore, in the inlet adsorption device 3, the volume of activated carbon that comes into contact with the gas to be treated can be reduced. In other words, the inlet adsorption device 3 can be made smaller. Therefore, with a small-scale device configuration, it is possible to efficiently suppress the intrusion of hydrocarbons into the absorption liquid.

[0045] Furthermore, in this embodiment, the inlet adsorption device 3 removes hydrocarbons from the gas to be treated that has been pressurized by the supply blower 31. By compressing the gas to be treated by the supply blower 31, the gas volume (flow rate) of the gas to be treated is further reduced. This makes it possible to further reduce the volume of activated carbon that comes into contact with the gas to be treated. This allows the inlet adsorption device 3 to be further miniaturized.

[0046] Furthermore, the first outlet adsorption device 9 brings the separated exhaust gas from which water has been separated in the gas-liquid separator 8 into contact with activated carbon to remove hydrocarbons remaining in the separated exhaust gas. In other words, hydrocarbons are removed from the regeneration tower exhaust gas discharged from the regeneration tower 5. Therefore, the inlet adsorption device 3 further removes hydrocarbons from the regeneration tower exhaust gas generated from the gas to be treated in a state in which hydrocarbons have already been removed and reduced. This makes it possible to increase the purity of the regeneration tower exhaust gas from which carbon dioxide has been removed. This makes it possible to improve the quality of the gas from which carbon dioxide has been removed that is finally discharged from the carbon dioxide capture system 1.

[0047] In particular, in this embodiment, the regeneration tower exhaust gas is converted into a separated exhaust gas from which moisture has been removed by the gas-liquid separator 8, and then hydrocarbons are removed. That is, the separated exhaust gas has a lower moisture concentration than the regeneration tower exhaust gas immediately after being discharged from the regeneration tower 5. The lower moisture concentration can improve the adsorption performance of activated carbon. As a result, hydrocarbons can be efficiently removed from the separated exhaust gas.

[0048] Second Embodiment Next, a carbon dioxide capture system 1A according to a second embodiment of the present disclosure will be described. In the second embodiment described below, components common to the first embodiment will be denoted by the same reference numerals in the drawings, and description thereof will be omitted. In the second embodiment, the carbon dioxide capture system 1A differs from the first embodiment in the configuration downstream of the first removal line.

[0049] In this embodiment, the upstream and downstream refer to the upstream and downstream in the flow direction of various gases and liquids flowing in the carbon dioxide capture system 1A.

[0050] In the carbon dioxide capture system 1A of the second embodiment, the separated exhaust gas sent to the first removal line L130 is not discharged to the outside as is. The separated exhaust gas sent to the first removal line L130 is further subjected to additional processes such as compression, dehydration, and removal of hydrocarbons. The carbon dioxide capture system 1A of the second embodiment further includes a first compressor 130, a first compression line L14, a first dehydration device 140, a first dehydration line L15, a second compressor 150, a second compression line L16, a second dehydration device 160, a second dehydration line L17, a second outlet adsorption device 170, a second removal line L18, a third compressor 180, a third compression line L19, a fourth compressor 190, a fourth compression line L20, a first dehydration drain line L21, a second dehydration drain line L22, a dehydration drain water adsorption device 220, a separated drain water adsorption device 230, a dehydration drain water line L23, a first drain water return line L25, and a second drain water return line L26.

[0051] (First Compressor) The first compressor 130 compresses the separated exhaust gas. The separated exhaust gas from which hydrocarbons have been removed is introduced into the first compressor 130 via a first removal line L130. The first compressor 130 is connected to the first outlet adsorption device 9 via the first removal line L130. The first compressor 130 discharges the compressed separated exhaust gas.

[0052] The first compression line L14 is capable of supplying the separated exhaust gas discharged from the first compressor 130 to the first dehydration device 140. The first compression line L14 is a pipe that connects the first compressor 130 and the first dehydration device 140.

[0053] (First Dehydration Device) The first dehydration device 140 is capable of removing moisture from the compressed separated exhaust gas. The compressed separated exhaust gas is introduced into the first dehydration device 140 via the first compression line L14. The first dehydration device 140 performs, for example, glycol dehydration on the compressed separated exhaust gas. The first dehydration device 140 absorbs water vapor from the separated exhaust gas to dehydrate it, for example, using a liquid desiccant. The first dehydration device 140 discharges a first dehydrated gas, which is the separated exhaust gas from which moisture has been removed, and dehydrated drain water, which is the removed moisture (drain water).

[0054] The first dehydration line L15 is capable of supplying the first dehydrated gas discharged from the first dehydration device 140 to the second compressor 150. The first dehydration line L15 is a pipe that connects the first dehydration device 140 and the second compressor 150.

[0055] (Second Compressor) The second compressor 150 compresses the first dehydrated gas. The second compressor 150 is connected to the first dehydration device 140 via a first dehydration line L15. That is, the second compressor 150 further compresses the separated exhaust gas after being compressed by the first compressor 130. The second compressor 150 is also coaxial with the first compressor 130 (having an integrated rotor). The first dehydrated gas is introduced into the second compressor 150 via the first dehydration line L15. The second compressor 150 discharges the compressed first dehydrated gas.

[0056] The second compression line L16 is capable of supplying the first dehydrated gas discharged from the second compressor 150 to the second dehydration device 160. The second compression line L16 is a pipe that connects the second compressor 150 and the second dehydration device 160.

[0057] (Second Dehydration Device) The second dehydration device 160 is capable of removing moisture from the compressed first dehydrated gas. The compressed first dehydrated gas is introduced into the second dehydration device 160 via the second compression line L16. The second dehydration device 160 performs, for example, glycol dehydration on the separated exhaust gas that has been dehydrated once and then compressed again. The second dehydration device 160 may have the same configuration as the first dehydration device 140 or may have a different configuration. The second dehydration device 160 absorbs water vapor from the separated exhaust gas to dehydrate it, for example, using a liquid desiccant. The second dehydration device 160 discharges second dehydrated gas, which is the first dehydrated gas from which moisture has been further removed, and dehydrated drain water, which is the removed moisture (drain water).

[0058] The second dehydration line L17 is capable of supplying the second dehydrated gas discharged from the second dehydration device 160 to the second outlet adsorption device 170. The second dehydration line L17 is a pipe connecting the second dehydration device 160 and the second outlet adsorption device 170.

[0059] (Second Outlet Adsorption Device) The second outlet adsorption device 170 is a second outlet adsorption device that contacts the regeneration tower exhaust gas discharged from the regeneration tower 5 with activated carbon to remove hydrocarbons remaining in the regeneration tower exhaust gas. In other words, the carbon dioxide capture system 1A of the second embodiment includes multiple outlet adsorption devices. The second outlet adsorption device 170 of this embodiment contacts the second dehydrated gas, which is the regeneration tower exhaust gas from which water has been removed in the second dehydration device 160, with activated carbon to remove hydrocarbons remaining in the second dehydrated gas. Similar to the first outlet adsorption device 9, the second outlet adsorption device 170 is capable of adsorbing high-boiling-point hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), onto activated carbon and removing them from the separated exhaust gas. The second outlet adsorption device 170 is introduced with the second dehydration line L17. The second outlet adsorption device 170 sends the second dehydrated gas from which hydrocarbons have been removed to the second removal line L18. The second outlet adsorption device 170 is, for example, a tank extending in the vertical direction, filled with activated carbon, and the second dehydrated gas can flow through the tank.

[0060] The second removal line L18 is capable of supplying the second dehydrated gas discharged from the second outlet adsorption device 170 to the third compressor 180. The second removal line L18 is a pipe that connects the second outlet adsorption device 170 and the third compressor 180.

[0061] (Third Compressor) The third compressor 180 compresses the supplied second dehydrated gas. The second dehydrated gas is introduced into the third compressor 180 via the second removal line L18. That is, the third compressor 180 further compresses the separated discharge gas after being compressed by the second compressor 150. The third compressor 180 is also coaxial with the first compressor 130 and the second compressor 150 (having an integrated rotor). The third compressor 180 is connected to the fourth compressor 190 via a third compression line L19. The third compressor 180 discharges the compressed second dehydrated gas.

[0062] The third compression line L19 is capable of supplying the second dehydrated gas discharged from the third compressor 180 to the fourth compressor 190. The third compression line L19 is a pipe that connects the third compressor 180 and the fourth compressor 190.

[0063] (Fourth Compressor) The fourth compressor 190 further compresses the supplied second dehydrated gas. The second dehydrated gas is introduced into the fourth compressor 190 via the third compression line L19. That is, the fourth compressor 190 further compresses the separated exhaust gas compressed by the third compressor 180. The fourth compressor 190 is coaxial with the first compressor 130, the second compressor 150, and the third compressor 180 (having an integrated rotor). In the second embodiment, the four compressors, the first compressor 130, the second compressor 150, the third compressor 180, and the fourth compressor 190, compress the regeneration tower exhaust gas to a state appropriate for the intended use, such as a supercritical state or a liquid state. The fourth compressor 190 discharges the compressed second dehydrated gas to the fourth compression line L20.

[0064] The fourth compression line L20 is capable of discharging the second dehydrated gas discharged from the fourth compressor 190 to the outside (outside the system). Similar to the first removal line L13 of the first embodiment, the fourth compression line L20 transfers the second dehydrated gas that has been compressed after hydrocarbons have been removed to an external destination depending on, for example, the intended use. The separated exhaust gas from which hydrocarbons have been removed and discharged from the fourth compression line L20 is transferred to a state depending on, for example, the intended use, and is stored in a tank, a tanker, a pipeline, inside an oil field, an aquifer, or the like.

[0065] The first dehydration drain line L21 supplies the dehydration drain water discharged from the first dehydration device 140 to the dehydration drain water adsorption device 220. The first dehydration drain line L21 is a pipe that connects the first dehydration device 140 and the dehydration drain water adsorption device 220.

[0066] The second dehydration drain line L22 supplies the dehydration drain water discharged from the second dehydration device 160 to the dehydration drain water adsorption device 220. The second dehydration drain line L22 supplies the dehydration drain water to the dehydration drain water adsorption device 220 via the first dehydration drain line L21. The second dehydration drain line L22 is a pipe connecting the second dehydration device 160 and the first dehydration drain line L21.

[0067] (Dehydrated Drain Water Adsorption Device) The dehydrated drain water adsorption device 220 is a drain water adsorption device that brings the dehydrated drain water supplied from the first dehydration device 140 and the second dehydration device 160 into contact with activated carbon to remove hydrocarbons remaining in the dehydrated drain water. That is, the dehydrated drain water adsorption device 220 brings the liquid dehydrated drain water into contact with activated carbon. The dehydrated drain water adsorption device 220 adsorbs high-boiling-point hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), onto the activated carbon, enabling them to be removed from the dehydrated drain water. The dehydrated drain water adsorption device 220 is introduced into the dehydrated drain water adsorption device 220 via a first dehydration drain line L21. The dehydrated drain water adsorption device 220 sends the dehydrated drain water, from which the hydrocarbons have been removed, to a dehydrated drain water line L23. The dehydration drain water adsorption device 220 is, for example, a tank extending in the vertical direction, filled with activated carbon, and the dehydration drain can flow through the tank.

[0068] The dehydration drain water line L23 supplies the dehydration drain water discharged from the dehydration drain water adsorption device 220 to the regeneration tower 5. The dehydration drain water line L23 merges the dehydration drain water with the drain water via the drain return line L110 and supplies the merged dehydration drain water to the regeneration tower 5. This causes the dehydration drain water and the drain water to merge with the absorbing liquid in the regeneration tower 5. The dehydration drain water line L23 is a pipe connecting the dehydration drain water adsorption device 220 and the drain return line L110. The dehydration drain water line L23 is connected to the drain return line L110 between the drain return pump 111 and the gas-liquid separator 8.

[0069] (Separated Drain Water Adsorption Device) The separated drain water adsorption device 230 is a drain water adsorption device that brings the separated drain water supplied from the gas-liquid separator 8 to the regeneration tower 5 into contact with activated carbon to remove hydrocarbons remaining in the separated drain water. That is, the carbon dioxide capture system 1A of the second embodiment is equipped with multiple drain water adsorption devices. The separated drain water adsorption device 230 of the second embodiment brings activated carbon into contact with a liquid formed by combining the separated drain water and the dehydrated drain water from which the hydrocarbons have been removed. The separated drain water adsorption device 230 adsorbs high-boiling hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), onto activated carbon, thereby enabling removal from the separated drain water. The separated drain water adsorption device 230 is arranged midway along the drain return line L110. The separated drain water adsorption device 230 is arranged between the drain return pump 111 and the regeneration tower 5. The pressurized separated drain water and dehydrated drain water are introduced into the separated drain water adsorption device 230 via the drain return line L110. The separated drain water adsorption device 230 sends the liquid from which hydrocarbons have been removed to the regeneration tower 5. The separated drain water adsorption device 230 is configured, for example, as a vertically extending tank filled with activated carbon, and a mixed liquid of the separated drain water and dehydrated drain can flow through the tank.

[0070] The first drain water return line L25 supplies a mixed liquid of separated drain water, which is drain water discharged from the separated drain water adsorption device 230, and dehydrated drain to the absorption tower 4. The first drain water return line L25 supplies a portion of the drain water discharged from the dehydrated drain water adsorption device 220 and supplied to the regeneration tower 5 to the water washing section 42. As a result, the separated drain water adsorption device 230, which is a drain water adsorption device, supplies the separated drain water that has been contacted with activated carbon to the water washing section 42. The first drain water return line L25 is a pipe that connects the drain return line L110 and the water washing section 42. The first drain water return line L25 is connected to the drain return line L110 between the separated drain water adsorption device 230 and the regeneration tower 5.

[0071] The second drain water return line L26 supplies dehydration drain, which is drain water discharged from the dehydration drain water adsorption device 220, to the absorption tower 4. The second drain water return line L26 supplies a portion of the dehydration drain water discharged from the dehydration drain water adsorption device 220 before merging with the drain return line L110 to the water washing unit 42. As a result, the dehydration drain water adsorption device 220, which is a drain water adsorption device, supplies the dehydration drain water that has been contacted with activated carbon to the water washing unit 42. The second drain water return line L26 is a pipe that connects the dehydration drain water line L23 and the first drain water return line L25. The second drain water return line L26 supplies the dehydration drain water to the first drain water return line L25, thereby supplying the dehydration drain water together with the mixed liquid to the water washing unit 42.

[0072] (Effects) In the carbon dioxide capture system 1A of the second embodiment, the second dehydrated gas dehydrated in the second dehydration device 160 is brought into contact with activated carbon by the second outlet adsorption device 170 to remove any remaining hydrocarbons. That is, hydrocarbons are removed from the regeneration tower exhaust gas discharged from the regeneration tower 5. Therefore, the inlet adsorption device 3 removes hydrocarbons from the regeneration tower exhaust gas generated from the gas to be treated in a state in which hydrocarbons have already been removed and reduced. Furthermore, because the second dehydrated gas is dehydrated in the second dehydration device 160, the water concentration is reduced, and the adsorption performance of the activated carbon can be improved. As a result, the efficiency of removing hydrocarbons from the second dehydrated gas can be improved. Therefore, the purity of the carbon dioxide gas finally discharged from the carbon dioxide capture system 1A can be increased, further improving its quality.

[0073] In addition, since the second dehydrated gas is compressed by the first compressor 130 and the second compressor 150, the gas volume (flow rate) of the second dehydrated gas is further reduced. Therefore, the volume of activated carbon that comes into contact with the second dehydrated gas can be further reduced. Therefore, the second outlet adsorption device 170 can be made smaller.

[0074] Furthermore, in the second embodiment, a second outlet adsorption device 170 is provided in addition to the first outlet adsorption device 9. That is, activated carbon is used by a plurality of outlet adsorption devices to remove hydrocarbons from the regeneration tower exhaust gas discharged from the regeneration tower 5. Therefore, the purity of the carbon dioxide gas finally discharged from the carbon dioxide capture system 1A can be further increased, and the quality can be further improved.

[0075] Furthermore, the gas from which hydrocarbons have been removed is discharged downstream by the first outlet adsorption device 9 and the second outlet adsorption device 170. As a result, only gas with reduced hydrocarbons can be supplied to equipment downstream of the second outlet adsorption device 170, such as the multiple compressors from the first compressor 130 to the fourth compressor 190 and the multiple dehydrators of the first dehydrator 140 and the second dehydrator 160. This makes it possible to suppress deposition and fouling of hydrocarbons in the downstream equipment. This improves the operational reliability of the compressors and dehydrators, and enables the operating time of the carbon dioxide capture system 1A to be extended.

[0076] Furthermore, in this embodiment, glycol dehydration is performed in the first dehydration device 140 and the second dehydration device 160. Comparing dehydration performance, glycol dehydration can dehydrate triethylene glycol (TEG) to several tens of ppm or less, and therefore carbon dioxide gas with a much lower moisture content can be obtained, which is incomparable to simple gas-liquid separation such as in the gas-liquid separator 8. Therefore, hydrocarbons can be removed with a smaller amount of adsorbent.

[0077] Furthermore, in the separated drain water adsorption device 230, the separated drain water discharged from the gas-liquid separator 8 is combined with the dehydrated drain water and then brought into contact with activated carbon to remove hydrocarbons. The separated drain water from which the hydrocarbons have been removed is then supplied to the regeneration tower 5 and combined with the absorbing liquid. Therefore, the absorbing liquid can be diluted with the liquid with reduced hydrocarbons. This reduces the concentration of hydrocarbons in the absorbing liquid. As a result, an increase in the concentration of hydrocarbons in the absorbing liquid during circulation between the regeneration tower 5 and the absorption tower 4 can be suppressed.

[0078] Furthermore, hydrocarbons are removed from the separated drain water and the dehydrated drain water rather than from the absorption liquid itself. The concentration of amines contained in the separated drain water and the dehydrated drain water is much lower than that in the absorption liquid. Therefore, rather than contacting the absorption liquid containing a high concentration of amines with activated carbon, contacting the separated drain water and the dehydrated drain water with activated carbon reduces the degree of inhibition of hydrocarbon adsorption by the activated carbon and improves the hydrocarbon adsorption performance. Therefore, by adopting a configuration in which hydrocarbons are removed from the drain water, hydrocarbons can be removed with a small amount of adsorbent.

[0079] Furthermore, the dehydrated drain water adsorption device 220 brings the dehydrated drain water, which is being supplied from the first dehydration device 140 to the regeneration tower 5, into contact with activated carbon to remove hydrocarbons. Therefore, the dehydrated drain water from which hydrocarbons have been removed is combined with the separated drain water, and then supplied to the regeneration tower 5 and combined with the absorbing liquid. In other words, an increase in the concentration of hydrocarbons in the separated drain water combined with the dehydrated drain water can be suppressed. Therefore, the absorbing liquid can be diluted with a liquid in which hydrocarbons have been further reduced. Therefore, the concentration of hydrocarbons in the absorbing liquid can be reduced. As a result, an increase in the concentration of hydrocarbons in the absorbing liquid can be suppressed during circulation between the regeneration tower 5 and the absorption tower 4.

[0080] Furthermore, the liquid from which hydrocarbons have been removed by the separated drain water adsorption device 230 and the dehydration drain water adsorption device 220 is discharged to the downstream regeneration tower 5. As a result, only liquid with reduced hydrocarbons can be supplied to equipment downstream of the separated drain water adsorption device 230 and the dehydration drain water adsorption device 220 (e.g., the drain return pump 111 and the regeneration tower 5). This makes it possible to suppress hydrocarbon precipitation and fouling in the downstream equipment. This improves the operational reliability of the drain return pump 111 and the regeneration tower 5, and enables the operating time of the carbon dioxide capture system 1A to be extended.

[0081] The first drain water return line L25 supplies a mixed liquid of the separated drain water and the dehydrated drain discharged from the separated drain water adsorption device 230 to the water washing section 42. The second drain water return line L26 supplies the dehydrated drain discharged from the dehydrated drain water adsorption device 220 to the water washing section 42. The hydrocarbons contained in the drain water discharged from the first dehydration device 140, the second dehydration device 160, and the gas-liquid separator 8 contain a high proportion of components that are likely to volatilize in the regeneration tower 5. If such drain water were returned to the water washing section 42 without passing it through activated carbon, the components that are likely to volatilize would pass through the water washing section 42 and be discharged into the atmosphere from the outlet of the absorption tower 4. However, by returning the separated drain water and the dehydrated drain that have passed through the separated drain water adsorption device 230 and the dehydrated drain adsorption device 220 to the water washing section 42, it is possible to prevent components that are likely to volatilize (or have a high vapor pressure) from being discharged into the atmosphere from the outlet of the absorption tower 4.

[0082] Third Embodiment Next, a carbon dioxide capture system 1B according to a third embodiment of the present disclosure will be described. In the third embodiment described below, components common to the first and second embodiments are denoted by the same reference numerals in the drawings, and descriptions thereof will be omitted. The third embodiment differs from the second embodiment in that it includes a coalescer 300 capable of separating hydrocarbons by oil-water separation.

[0083] The carbon dioxide capture system 1B of the third embodiment is capable of removing hydrocarbons from the rich liquid flowing through the rich line L6. The carbon dioxide capture system 1B further includes a coalescer 300.

[0084] (Coalescer) The coalescer 300 is capable of separating hydrocarbons from the rich liquid or the lean liquid by oil-water separation. The coalescer 300 of this embodiment is supplied with the rich liquid discharged from the absorption tower 4 before being supplied to the absorbent heat exchanger 6. The coalescer 300 is disposed midway along the rich line L6. The coalescer 300 is disposed in the rich line L6 between the rich pump 61 and the absorbent heat exchanger 6. The coalescer 300 is, for example, a cylindrical filter. As the rich liquid passes through the interior, the coalescer 300 coarsens and adsorbs hydrocarbons that have become fine oil particles in the emulsion on the filter fiber surface. The rich liquid from which the hydrocarbons have been separated is then discharged from the coalescer 300. The coalescer 300 separates hydrocarbons from the entire amount of rich liquid flowing through the rich line L6. The coalescer 300 is not limited to a structure disposed in the rich line L6. The coalescer 300 may be configured to be disposed in the lean line L8 and separate hydrocarbons from the lean liquid.

[0085] (Effects) In the carbon dioxide capture system 1B of the third embodiment, the coalescer 300 separates hydrocarbons from the rich liquid flowing through the rich line L6. In particular, in this embodiment, hydrocarbons are separated from the entire amount of rich liquid flowing through the rich line L6. In other words, hydrocarbons can be removed from the absorption liquid circulating between the regeneration tower 5 and the absorption tower 4. In particular, absorption liquids such as aqueous amine solutions, which are high-concentration liquids, incorporate hydrocarbons and become an emulsion. In contrast, by placing the coalescer 300 in the rich line L6 instead of activated carbon or a filter, fine hydrocarbons contained in the emulsion can be efficiently recovered. Therefore, accumulation of hydrocarbons in the circulating absorption liquid can be suppressed.

[0086] Furthermore, since the coalescer 300 is disposed on the rich line L6 instead of the lean line L8, hydrocarbons can be removed from the absorption solution in which the concentration of hydrocarbons is high together with amines. Therefore, hydrocarbons can be recovered more efficiently than when the coalescer 300 is disposed on the lean line L8.

[0087] (Other Embodiments) Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope that does not deviate from the gist of the present disclosure are also included.

[0088] The configurations of the first to third embodiments may be combined in various ways. For example, the configuration of the first embodiment may be combined with the configuration of the third embodiment.

[0089] Furthermore, the inlet adsorption device 3, the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230 are not limited to a configuration in which only one is arranged for each gas or liquid, as in the above embodiment. Multiple inlet adsorption devices 3, the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230 may be arranged in parallel for each gas or liquid. For example, as shown in FIG. 4 , in the carbon dioxide capture system 1C, the inlet adsorption device 3, the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230 are arranged in parallel, allowing them to be switched and used in emergency situations such as when each device is blocked (pressure drop increases) or performance deteriorates. As a result, the carbon dioxide capture system 1C can continue to operate stably.

[0090] Furthermore, unlike the second embodiment, the carbon dioxide capture systems 1, 1A, 1B, and 1C are not limited to a configuration including all of the inlet adsorption device 3, the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230. As long as the carbon dioxide capture systems 1, 1A, and 1B have the inlet adsorption device 3, they may not be provided with any of the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230. Furthermore, only one or some of the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230 may be provided. In this case, the combination of the lean liquid adsorption device 7, the first outlet adsorption device 9, the second outlet adsorption device 170, the dehydration drain water adsorption device 220, and the separation drain water adsorption device 230 can be set appropriately.

[0091] <Additional Notes> The acid gas recovery system described in each embodiment can be understood, for example, as follows.

[0092] (1) The acidic gas recovery system according to the first aspect includes a cooling tower 2 into which a gas to be treated containing an acidic gas is introduced and which cools the gas to be treated; an inlet adsorption device 3 that brings the gas to be treated cooled in the cooling tower 2 into contact with activated carbon to remove hydrocarbons remaining in the gas to be treated; an absorption tower 4 into which the gas to be treated from which the hydrocarbons have been removed in the inlet adsorption device 3 is introduced and which brings the gas to be treated into contact with an absorption liquid and discharges the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; and a regeneration tower 5 that strips the acidic gas from the absorption liquid discharged from the absorption tower 4 and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas.

[0093] According to this configuration, the gas to be treated cooled in the cooling tower 2 is supplied to the inlet adsorption device 3, where it comes into contact with activated carbon and hydrocarbons are removed. This makes it possible to prevent hydrocarbons from flowing into the absorption tower 4. Furthermore, in the inlet adsorption device 3, hydrocarbons are removed from the gas to be treated after being cooled in the cooling tower 2. The gas to be treated after being cooled in the cooling tower 2 not only has a lowered gas temperature, but also has a lowered moisture concentration as the gas temperature decreases. The lowered moisture concentration improves the adsorption performance of the activated carbon for hydrocarbons in the gas to be treated after being cooled, compared to the gas to be treated before being cooled. As a result, the activated carbon is efficiently used to adsorb hydrocarbons, and the incorporation of hydrocarbons into the absorption liquid can be efficiently prevented.

[0094] (2) The acidic gas recovery system according to the second aspect is the acidic gas recovery system of (1), further comprising an outlet adsorption device that contacts the regeneration tower exhaust gas discharged from the regeneration tower 5 with activated carbon to remove the hydrocarbons remaining in the regeneration tower exhaust gas.

[0095] With this configuration, hydrocarbons are removed from the regeneration tower exhaust gas discharged from the regeneration tower 5. Therefore, the inlet adsorption device 3 further removes hydrocarbons from the regeneration tower exhaust gas generated from the gas to be treated, which has already had hydrocarbons removed and is therefore reduced in content. This makes it possible to increase the purity of the regeneration tower exhaust gas from which carbon dioxide has been removed. This makes it possible to improve the quality of the gas from which carbon dioxide has been removed that is finally discharged from the carbon dioxide capture systems 1, 1A, and 1B.

[0096] (3) The acidic gas recovery system according to the third aspect is the acidic gas recovery system of (2), further comprising a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower 5, and the outlet adsorption device brings the regeneration tower exhaust gas discharged from the dehydration device into contact with activated carbon.

[0097] With this configuration, the regeneration tower exhaust gas is dehydrated in the dehydrator, thereby reducing the moisture concentration and improving the adsorption performance of the activated carbon. As a result, the efficiency of removing hydrocarbons from the regeneration tower exhaust gas discharged from the dehydrator can be improved. Therefore, the purity of the gas from which carbon dioxide has been removed and which is finally discharged from the carbon dioxide capture systems 1, 1A, and 1B can be increased, further improving its quality.

[0098] (4) The acidic gas recovery system according to the fourth aspect is any one of the acidic gas recovery systems (1) to (3), and further includes a gas-liquid separator (8) that separates moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower (5), discharges the separated exhaust gas from which the moisture has been separated, and supplies the separated moisture to the regeneration tower (5) as drain water; and a drain water adsorption device (230) that contacts the drain water supplied from the gas-liquid separator (8) to the regeneration tower (5) with activated carbon to remove the hydrocarbons remaining in the drain water.

[0099] According to this configuration, the drain water from which hydrocarbons have been removed is supplied to the regeneration tower 5 and combined with the absorbing liquid. Therefore, the absorbing liquid can be diluted with the liquid with reduced hydrocarbons. This reduces the concentration of hydrocarbons in the absorbing liquid. As a result, it is possible to prevent the concentration of hydrocarbons in the absorbing liquid from increasing during circulation between the regeneration tower 5 and the absorption tower 4.

[0100] (5) The acidic gas recovery system according to the fifth aspect is any one of the acidic gas recovery systems (1) to (4), further comprising a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower (5) and supplies the absorbed moisture to the regeneration tower (5) as dehydrated drain water, and further comprising a dehydrated drain water adsorption device (220) that contacts the dehydrated drain water supplied from the dehydration device to the regeneration tower (5) with activated carbon to remove the hydrocarbons remaining in the dehydrated drain water.

[0101] According to this configuration, the dehydrated drain water from which hydrocarbons have been removed is supplied to the regeneration tower 5 and merged with the absorbing liquid. Therefore, the absorbing liquid can be diluted with the dehydrated drain water from which hydrocarbons have been reduced. This reduces the concentration of hydrocarbons in the absorbing liquid. As a result, it is possible to prevent the concentration of hydrocarbons in the absorbing liquid from increasing during circulation between the regeneration tower 5 and the absorption tower 4.

[0102] (6) The acidic gas recovery system according to the sixth aspect is any one of the acidic gas recovery systems (1) to (5), and further includes a rich line (L6) that supplies a rich liquid, which is the absorption liquid that has absorbed the acidic gas, from the absorption tower (4) to the regeneration tower (5), a lean line (L8) that supplies a lean liquid, which is the absorption liquid from which the acidic gas has been stripped, from the regeneration tower (5) to the absorption tower (4), and a coalescer (300) that separates the hydrocarbons from the rich liquid or lean liquid by oil-water separation.

[0103] With this configuration, hydrocarbons can be removed from the absorption liquid circulating between the regeneration tower 5 and the absorption tower 4, and therefore accumulation of hydrocarbons in the circulating absorption liquid can be suppressed.

[0104] (7) The acidic gas recovery system according to the seventh aspect is the acidic gas recovery system of (6), further comprising an absorption liquid heat exchanger 6 that performs heat exchange between the rich liquid flowing through the rich line L6 and the lean liquid flowing through the lean line L8, thereby heating the rich liquid and cooling the lean liquid, and the coalescer 300 separates the hydrocarbons from the rich liquid discharged from the absorption tower 4 and before it is supplied to the absorption liquid heat exchanger 6 by oil-water separation.

[0105] According to this configuration, the coalescer 300 is disposed on the rich line L6 instead of the lean line L8, so that hydrocarbons can be removed from the absorption solution in which the concentration of hydrocarbons is high together with amines. Therefore, hydrocarbons can be recovered more efficiently than when the coalescer 300 is disposed on the lean line L8.

[0106] (8) The acid gas recovery system according to the eighth aspect is any one of the acid gas recovery systems (1) to (7), in which the inlet adsorption device 3 is connected in parallel to the cooling tower 2 and the absorption tower 4 in multiple units.

[0107] This configuration allows switching to be used in emergency situations such as when each device is blocked (pressure drop increases) or performance deteriorates, allowing the carbon dioxide capture system to continue operating stably.

[0108] (9) An acidic gas recovery system according to a ninth aspect includes an absorption tower 4 into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered, the absorption tower 4 brings the gas to be treated into contact with an absorption liquid, and discharges the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; a regeneration tower 5 that strips the acidic gas from the absorption liquid discharged from the absorption tower 4, and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas; and a regeneration tower exhaust gas discharged from the regeneration tower 5. The system includes a gas-liquid separator 8 that separates moisture contained in the outlet gas, discharges the separated exhaust gas from which the moisture has been separated, and supplies the separated moisture to the regeneration tower as drain water, a dehydrator 140, 160 that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower 5, and a drain water adsorption device 220, 230 that brings the drain water supplied to the regeneration tower 5 from at least one of the gas-liquid separator 8 and the dehydrator 140, 160 into contact with activated carbon to remove hydrocarbons remaining in the drain water.

[0109] According to this configuration, hydrocarbons are removed from the drain water, rather than from the absorption liquid itself. The concentration of amines contained in the drain water is much lower than that in the absorption liquid. Therefore, by contacting the drain water with activated carbon rather than contacting an absorption liquid containing a high concentration of amines with activated carbon, the degree of inhibition of hydrocarbon adsorption by activated carbon can be reduced and the hydrocarbon adsorption performance can be improved. Therefore, by adopting a configuration in which hydrocarbons are removed from the drain water, hydrocarbons can be removed with a small amount of adsorbent.

[0110] (10) The acidic gas recovery system according to the tenth aspect is the acidic gas recovery system of (9), wherein the drain water adsorption device 230 brings the drain water discharged from the gas-liquid separator 8 into contact with the activated carbon.

[0111] With this configuration, the absorbing liquid can be diluted with a liquid with reduced hydrocarbons. Therefore, the concentration of hydrocarbons in the absorbing liquid can be reduced. As a result, an increase in the concentration of hydrocarbons in the absorbing liquid during circulation between the regenerator 5 and the absorber 4 can be suppressed.

[0112] (11) The acid gas recovery system according to the eleventh aspect is the acid gas recovery system of (9) or (10), wherein the drain water adsorption device 220 brings the drain water discharged from the dehydration devices 140, 160 into contact with the activated carbon.

[0113] This configuration can suppress an increase in the concentration of hydrocarbons in the drain water. Therefore, the absorption liquid can be diluted with a liquid containing an even lower amount of hydrocarbons. This reduces the concentration of hydrocarbons in the absorption liquid. As a result, an increase in the concentration of hydrocarbons in the absorption liquid during circulation between the regeneration tower 5 and the absorption tower 4 can be suppressed.

[0114] (12) The acid gas recovery system according to the twelfth aspect is any one of the acid gas recovery systems (9) to (11), wherein the drain water adsorption devices 220, 230 supply the drain water that has been contacted with the activated carbon to the regeneration tower 5.

[0115] With this configuration, only liquid with reduced hydrocarbons can be supplied to the equipment downstream of the drain water adsorption devices 220, 230. This can suppress hydrocarbon deposition and fouling in the downstream equipment. This improves the operational reliability of the downstream equipment and extends the operating time of the carbon dioxide capture system.

[0116] (13) The acidic gas recovery system according to a thirteenth aspect is any one of the acidic gas recovery systems (9) to (12), wherein the absorption tower (4) includes a recovery section (41) that brings the gas to be treated into contact with the absorption liquid and causes the absorption liquid to recover the acidic gas, and a water washing section (42) that brings the decarbonated gas that has come into contact with the absorption liquid in the recovery section (41) into contact with wash water and recovers the absorption liquid components entrained in the decarbonated gas, and the drain water adsorption devices (220, 230) supply the drain water that has come into contact with the activated carbon to the water washing section (42).

[0117] With this configuration, the hydrocarbons contained in the drain water discharged from the dehydrators 140, 160 and the gas-liquid separator 8 have a high proportion of components that are likely to volatilize in the regeneration tower 5. If such drain water is returned to the water washing section 42 without passing it through activated carbon, the components that are likely to volatilize may pass through the water washing section 42 and be discharged into the atmosphere from the outlet of the absorption tower 4. However, by returning the drain that has passed through the drain water adsorption devices 220, 230 to the water washing section 42, it is possible to prevent components that are likely to volatilize (or have a high vapor pressure) from being discharged into the atmosphere from the outlet of the absorption tower 4.

[0118] (14) The acid gas recovery system according to the fourteenth aspect is any one of the acid gas recovery systems (9) to (13), further comprising an outlet adsorption device (9, 170) that contacts the regeneration tower exhaust gas discharged from the regeneration tower (5) with activated carbon to remove the hydrocarbons remaining in the regeneration tower exhaust gas.

[0119] With this configuration, the regeneration tower exhaust gas is dehydrated in the dehydrators 140 and 160, thereby lowering the moisture concentration and improving the adsorption performance of the activated carbon. As a result, the efficiency of removing hydrocarbons from the regeneration tower exhaust gas can be improved. Therefore, the purity of the carbon dioxide gas finally emitted from the carbon dioxide capture system can be increased, further improving its quality.

[0120] (15) The acidic gas recovery system according to the fifteenth aspect is any one of the acidic gas recovery systems (9) to (14), and further includes a rich line L6 that supplies a rich liquid, which is the absorption liquid that has absorbed the acidic gas, from the absorption tower 4 to the regeneration tower 5, a lean line L8 that supplies a lean liquid, which is the absorption liquid from which the acidic gas has been stripped, from the regeneration tower 5 to the absorption tower 4, and a coalescer 300 that separates the hydrocarbons from the rich liquid or the lean liquid by oil-water separation.

[0121] With this configuration, hydrocarbons can be removed from the absorption liquid circulating between the regeneration tower 5 and the absorption tower 4, and therefore accumulation of hydrocarbons in the circulating absorption liquid can be suppressed.

[0122] (16) The acidic gas recovery system according to the sixteenth aspect is the acidic gas recovery system of (15), further comprising an absorption liquid heat exchanger 6 that performs heat exchange between the rich liquid flowing through the rich line L6 and the lean liquid flowing through the lean line L8, thereby heating the rich liquid and cooling the lean liquid, and the coalescer 300 separates the hydrocarbons from the rich liquid discharged from the absorption tower 4 and before it is supplied to the absorption liquid heat exchanger 6 by oil-water separation.

[0123] According to this configuration, the coalescer 300 is disposed on the rich line L6 instead of the lean line L8, so that hydrocarbons can be removed from the absorption solution in which the concentration of hydrocarbons is high together with amines. Therefore, hydrocarbons can be recovered more efficiently than when the coalescer 300 is disposed on the lean line L8.

[0124] (17) The acidic gas recovery system according to the seventeenth aspect includes an absorption tower 4 into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered, which contacts the gas to be treated with an absorption liquid and discharges the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; a regeneration tower 5 that strips the acidic gas from the absorption liquid discharged from the absorption tower 4 and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas; a dehydration device 140, 160 that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower 5; and an outlet adsorption device 9, 170 that contacts the regeneration tower exhaust gas from which moisture has been removed in the dehydration device 140, 160 with activated carbon to remove hydrocarbons remaining in the regeneration tower exhaust gas.

[0125] With this configuration, the regeneration tower exhaust gas is dehydrated in the dehydrators 140 and 160, thereby lowering the moisture concentration and improving the adsorption performance of the activated carbon. As a result, the efficiency of removing hydrocarbons from the regeneration tower exhaust gas can be improved. Therefore, the purity of the carbon dioxide gas finally emitted from the carbon dioxide capture system can be increased, further improving its quality.

[0126] According to the acid gas recovery system of the present disclosure, it is possible to efficiently suppress the incorporation of hydrocarbons into the absorption liquid and the accumulation of degradation products in the absorption liquid.

[0127] 1, 1A, 1B, 1C Carbon dioxide recovery system (acid gas recovery system) L1 Supply line 2 Cooling tower L2 Supply cooling circulation line 21 Supply circulation pump 22 Supply circulation cooler L3 Cooler discharge line 31 Supply blower 3 Inlet adsorption device L4 Inlet adsorption line 4 Absorption tower 41 Recovery section 42 Water washing section 43 Absorption tower circulation section 431 Absorption tower circulation pump 432 Absorption tower circulation heat exchanger L5 Absorption tower discharge line L6 Rich line 61 Rich pump 5 Regeneration tower 51 Reboiler L7 Regeneration tower exhaust gas line 71 Regeneration tower exhaust gas condenser L8 Lean line 81 Lean pump 82 Lean cooler 6 Absorption liquid heat exchanger L9 Lean liquid adsorption supply line 7 Lean liquid adsorption device L10 Lean liquid adsorption discharge line 8 Gas-liquid separator L11, L110 Drain return line 111 Drain return pump L12 Separated exhaust gas line 9 First outlet adsorption device L13, L130 First removal line 130 First compressor L14 First compression line 140 First dehydration device L15 First dehydration line 150 Second compressor L16 Second compression line 160 Second dehydration device L17 Second dehydration line 170 Second outlet adsorption device L18 Second removal line 180 Third compressor L19 Third compression line 190 Fourth compressor L20 Fourth compression line L21 First dehydration drain line L22 Second dehydration drain line 220 Dehydration drain water adsorption device L23 Dehydration drain water line 230 Separation drain water adsorption device 300 Coalescer L25 First drain water return line L26 Second drain water return line

Claims

1. An acid gas recovery system comprising: a cooling tower into which a gas to be treated containing an acid gas is introduced and which cools the gas to be treated; an inlet adsorption device which brings the gas to be treated cooled in the cooling tower into contact with activated carbon to remove hydrocarbons remaining in the gas to be treated; an absorption tower into which the gas to be treated from which the hydrocarbons have been removed in the inlet adsorption device is introduced and which brings the gas to be treated into contact with an absorption liquid and discharges the absorption liquid which has absorbed the acid gas and an absorption tower exhaust gas containing the gas to be treated from which the acid gas has been removed; and a regeneration tower which strips the acid gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acid gas has been stripped and a regeneration tower exhaust gas containing the acid gas.

2. The acid gas recovery system described in claim 1, further comprising an outlet adsorption device that contacts the regeneration tower exhaust gas discharged from the regeneration tower with activated carbon to remove the hydrocarbons remaining in the regeneration tower exhaust gas.

3. An acid gas recovery system as described in claim 2, further comprising a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower, and the outlet adsorption device brings the regeneration tower exhaust gas discharged from the dehydration device into contact with activated carbon.

4. The acid gas recovery system according to claim 1 or 2, further comprising: a gas-liquid separator that separates moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower, discharges the separated exhaust gas from which the moisture has been separated, and supplies the separated moisture to the regeneration tower as drain water; and a drain water adsorption device that brings the drain water supplied from the gas-liquid separator to the regeneration tower into contact with activated carbon to remove the hydrocarbons remaining in the drain water.

5. An acid gas recovery system as described in claim 1 or 2, further comprising a dehydration device that absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower and supplies the absorbed moisture to the regeneration tower as dehydrated drain water, and a dehydrated drain water adsorption device that contacts the dehydrated drain water supplied from the dehydration device to the regeneration tower with activated carbon to remove the hydrocarbons remaining in the dehydrated drain water.

6. An acidic gas recovery system as described in claim 1 or 2, further comprising: a rich line for supplying a rich liquid, which is the absorption liquid that has absorbed the acidic gas, from the absorption tower to the regeneration tower; a lean line for supplying a lean liquid, which is the absorption liquid from which the acidic gas has been released, from the regeneration tower to the absorption tower; and a coalescer that separates the hydrocarbons from the rich liquid or the lean liquid by oil-water separation.

7. An acid gas recovery system as described in claim 6, further comprising an absorption liquid heat exchanger that performs heat exchange between the rich liquid flowing through the rich line and the lean liquid flowing through the lean line, heating the rich liquid and cooling the lean liquid, and wherein the coalescer separates the hydrocarbons from the rich liquid by oil-water separation before it is discharged from the absorption tower and supplied to the absorption liquid heat exchanger.

8. An acid gas recovery system according to claim 1 or 2, wherein a plurality of the inlet adsorption devices are connected in parallel to the cooling tower and the absorption tower.

9. An acidic gas recovery system comprising: an absorption tower into which a gas to be treated containing an acidic gas is introduced as a gas to be recovered, which contacts the gas to be treated with an absorption liquid and discharges the absorption liquid that has absorbed the acidic gas and an absorption tower exhaust gas containing the gas to be treated from which the acidic gas has been removed; a regeneration tower which strips the acidic gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acidic gas has been stripped and a regeneration tower exhaust gas containing the acidic gas; a gas-liquid separator which separates moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower, discharges a separated exhaust gas from which the moisture has been separated, and supplies the separated moisture to the regeneration tower as drain water; a dehydration device which absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower; and a drain water adsorption device which contacts the drain water supplied to the regeneration tower from at least one of the gas-liquid separator and the dehydration device with activated carbon to remove hydrocarbons remaining in the drain water.

10. The acid gas recovery system according to claim 9, wherein the drain water adsorption device brings the drain water discharged from the gas-liquid separator into contact with the activated carbon.

11. An acid gas recovery system according to claim 9 or 10, wherein the drain water adsorption device brings the drain water discharged from the dehydration device into contact with the activated carbon.

12. An acid gas recovery system according to claim 9 or 10, wherein the drain water adsorption device supplies the drain water that has been brought into contact with the activated carbon to the regeneration tower.

13. The absorption tower comprises a recovery section that brings the gas to be treated into contact with the absorption liquid and causes the absorption liquid to recover the acidic gas, and a water washing section that brings the decarbonated gas after contact with the absorption liquid in the recovery section into contact with wash water and recovers the absorption liquid components entrained in the decarbonated gas, and the drain water adsorption device supplies the drain water that has been contacted with the activated carbon to the water washing section. An acidic gas recovery system as described in claim 9 or 10.

14. An acid gas recovery system as described in claim 9 or 10, further comprising an outlet adsorption device that contacts the regeneration tower exhaust gas discharged from the regeneration tower with activated carbon to remove the hydrocarbons remaining in the regeneration tower exhaust gas.

15. An acid gas recovery system as described in claim 9 or 10, further comprising: a rich line for supplying a rich liquid, which is the absorption liquid that has absorbed the acid gas, from the absorption tower to the regeneration tower; a lean line for supplying a lean liquid, which is the absorption liquid from which the acid gas has been released, from the regeneration tower to the absorption tower; and a coalescer that separates the hydrocarbons from the rich liquid or the lean liquid by oil-water separation.

16. An acid gas recovery system as described in claim 15, further comprising an absorption liquid heat exchanger that performs heat exchange between the rich liquid flowing through the rich line and the lean liquid flowing through the lean line, heating the rich liquid and cooling the lean liquid, and wherein the coalescer separates the hydrocarbons from the rich liquid by oil-water separation before it is discharged from the absorption tower and supplied to the absorption liquid heat exchanger.

17. An acid gas recovery system comprising: an absorption tower into which a gas to be treated containing an acid gas is introduced as a gas to be recovered, which brings the gas to be treated into contact with an absorption liquid and discharges the absorption liquid that has absorbed the acid gas and an absorption tower exhaust gas containing the gas to be treated from which the acid gas has been removed; a regeneration tower which strips the acid gas from the absorption liquid discharged from the absorption tower and discharges the absorption liquid from which the acid gas has been stripped and a regeneration tower exhaust gas containing the acid gas; a dehydration device which absorbs moisture contained in the regeneration tower exhaust gas discharged from the regeneration tower; and an outlet adsorption device which brings the regeneration tower exhaust gas from which moisture has been removed by the dehydration device into contact with activated carbon and removes hydrocarbons remaining in the regeneration tower exhaust gas.

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