Gas treatment device

Abstract

The gas treatment device includes: an absorption device that receives an absorption liquid and causes the absorption liquid to absorb an acidic compound in a gas to be treated; a release device into which the absorption liquid in which the acidic compound is absorbed in the absorption device is introduced; a heating section that heats the absorption liquid in the release device to cause the acidic compound contained in the absorption liquid to be released from the absorption liquid; and a multi-fluid heat exchanger that heats the absorption liquid supplied from the absorption device to the release device before the absorption liquid is supplied from the release device to the absorption device by a fluid containing the acidic compound released from the release device.

Description

Technical Field

[0001] This invention relates to a gas processing device. Background Technology

[0002] Previously, various methods were known for recovering acidic compounds from large volumes of gas containing acidic compounds such as carbon dioxide (CO2), such as exhaust gas from power plants or by-product gas from blast furnaces. Examples of such recovery methods include chemical absorption methods such as amine absorption. In chemical absorption methods, alkaline aqueous solutions such as amine solutions are used as absorbents. When CO2-containing gas is brought into contact with this absorbent, the CO2 is absorbed by the absorbent. Subsequently, by heating the absorbent that has absorbed CO2, CO2 can be released from the absorbent. Therefore, the released CO2 can be recovered.

[0003] In chemical absorption methods using amine-based absorbents, the process of releasing carbon dioxide from the amine solution that has absorbed carbon dioxide (commonly referred to as the liquid regeneration process) requires a large amount of heat energy, which is one of the reasons for the high separation cost. As a method to reduce the energy consumption of the absorbent regeneration process, a common approach is to recover excess heat from the process. This is often achieved by exchanging heat between the low-temperature liquid (rich liquid) accumulated at the bottom of the CO2 absorption tower and the high-temperature liquid (lean liquid) accumulated at the bottom of the CO2 release tower. Furthermore, for example, in the carbon dioxide recovery device disclosed in Patent Document 1 below, such as... Figure 7 As shown, in addition to a regeneration heat exchanger 83 that heats the rich liquid with the lean liquid flowing out of the discharge tower 81, a carbon dioxide generator 85 is also provided that heats the rich liquid with carbon dioxide-containing water vapor flowing out of the discharge tower 81. Therefore, a flow divider 89 is provided to divert the rich liquid from the CO2 absorption tower 87 to a flow path toward the regeneration heat exchanger 83 and to a flow path toward the carbon dioxide generator 85.

[0004] In the recovery device disclosed in Patent Document 1, not only is the lean liquid used to heat the rich liquid, but also carbon dioxide-containing water vapor is used for heating, thus improving the heat recovery efficiency. However, a diverter 89 is required to split the rich liquid into a flow path toward the regeneration heat exchanger 83 and a flow path toward the carbon dioxide generator 85, and the required heat recovery efficiency cannot be obtained if the flow rate through each flow path is not designed to be optimal.

[0005] Patent Document 1: Japanese Patent Publication No. 2014-4525 Summary of the Invention

[0006] The object of this invention is to achieve the required heat recovery efficiency using lean liquid and fluid containing acidic compounds without requiring a split-flow design.

[0007] One aspect of the present invention relates to a gas treatment apparatus comprising: an absorption device for receiving an absorbent liquid, wherein the absorbent liquid absorbs an acidic compound in a gas to be treated; a discharge device for introducing the absorbent liquid, in which the acidic compound has been absorbed, into the absorption device; a heating unit for heating the absorbent liquid in the discharge device to release the acidic compound contained in the absorbent liquid; and a multi-fluid heat exchanger for heating the absorbent liquid supplied from the absorption device to the discharge device via a fluid containing the acidic compound released from the discharge device and the absorbent liquid supplied from the discharge device to the absorption device. Attached Figure Description

[0008] Figure 1 This is a diagram that roughly illustrates the overall structure of the gas processing apparatus according to the first embodiment.

[0009] Figure 2 This is a diagram that roughly illustrates the overall structure of the gas processing apparatus according to a variation of the first embodiment.

[0010] Figure 3 This is a diagram that roughly illustrates the overall structure of the gas processing apparatus according to the second embodiment.

[0011] Figure 4 This is a diagram that roughly illustrates the overall structure of the gas processing apparatus according to the third embodiment.

[0012] Figure 5 This is a diagram that roughly illustrates the overall structure of the gas processing apparatus according to the fourth embodiment.

[0013] Figure 6A It is a diagram that roughly represents the structure of a multifluid heat exchanger.

[0014] Figure 6B It is a diagram that roughly represents the structure of a multifluid heat exchanger.

[0015] Figure 7 This is a diagram showing the structure of a conventional carbon dioxide recovery device. Detailed Implementation

[0016] Hereinafter, embodiments will be described with reference to the accompanying drawings. Furthermore, these embodiments are merely examples embodying the present invention and are not intended to limit the scope of the invention.

[0017] (First Implementation)

[0018] Figure 1The gas treatment apparatus 10 shown in the first embodiment is an apparatus for separating acidic compounds from a gas being treated by chemical absorption using an amine-based absorbent. The acidic compounds separated by the gas treatment apparatus 10 are not particularly limited as long as they are compounds that become acidic in aqueous solution; examples include hydrogen chloride, carbon dioxide, sulfur dioxide, or carbon disulfide. The acidic compounds are gaseous compounds that dissolve in water to produce acid.

[0019] like Figure 1 As shown, the gas processing apparatus 10 includes an absorption device 12, a discharge device 14, a circulation path 16, and a multi-fluid heat exchanger 18. The circulation path 16 has a rich liquid flow path 21 that draws absorbent from the absorption device 12 and introduces it into the discharge device 14, and a lean liquid flow path 22 that draws absorbent from the discharge device 14 and returns it to the absorption device 12.

[0020] The absorption device 12 is connected to a gas supply path 24 for supplying a gas to be treated, such as a gas containing CO2, i.e., a process gas; a gas discharge path 26 for discharging the treated gas; a rich liquid flow path 21 for conveying the absorbent to the discharge device 14; and a lean liquid flow path 22 for returning the absorbent from the discharge device 14 to the absorption device 12.

[0021] Gas supply path 24 is connected to the lower part of the absorber 12 located at the bottom side. Gas discharge path 26 is connected to the upper end of the absorber 12 located at the top side. Rich liquid flow path 21 is connected to the bottom of the absorber 12, in other words, connected to or near the lower end. That is, rich liquid flow path 21 is connected to a position where the absorbent liquid accumulated in the absorber 12 can be extracted. Lean liquid flow path 22 is connected to the top of the absorber 12, in other words, connected to or near the upper end. That is, lean liquid flow path 22 is connected to a position where the absorbent liquid returning from the discharge device 14 can flow down from above. A cooler 28 for cooling the absorbent liquid is provided in the lean liquid flow path 22. Alternatively, the cooler 28 may be omitted.

[0022] The absorption device 12 is formed in a vertically elongated shape, so that the gas to be treated, introduced through the gas supply path 24, comes into contact with the low-temperature absorbent introduced through the lean liquid flow path 22. That is, inside the absorption device 12, the absorbent flows down from the top of the absorption device 12, while the gas to be treated flows upward from the bottom of the absorption device 12. As a result, acidic compounds in the gas to be treated are absorbed by the absorbent. The treated gas after the acidic compounds have been removed is discharged through the gas discharge path 26, and the absorbent (rich liquid) that has absorbed the acidic compounds flows through the rich liquid flow path 21.

[0023] The absorption device 12 can have any structure as long as it is configured to continuously contact the gas to be treated with the absorbent. For example, the absorption device 12 can be configured to spray the absorbent into the flow path of the gas to be treated, or it can be configured to allow the absorbent to flow down along a packing material disposed in the flow path of the gas to be treated. Furthermore, the absorption device 12 can also be configured to have a plurality of micro-flow paths for separately introducing the gas to be treated and the absorbent, and to merge the micro-flow paths of the gas to be treated and the micro-flow paths of the absorbent. Additionally, the absorption device 12 can be configured to accumulate the introduced absorbent and supply the gas to be treated to the accumulated absorbent. Furthermore, the absorption of acidic compounds in the absorption device 12 is an exothermic reaction. The heat of reaction generated in the absorption device 12 causes the temperature of the gas to be treated and the absorbent to rise.

[0024] The discharge device 14 is formed in a vertically elongated shape, configured to allow the absorbent liquid introduced through the rich liquid flow path 21 to flow down within the discharge device 14.

[0025] The discharge device 14 is equipped with a heating section 30 for heating the absorbent stored in the discharge device 14. By heating the absorbent with the heating section 30, acidic compounds are released from the absorbent in the discharge device 14. The release of acidic compounds from the absorbent is an endothermic reaction. In the discharge device 14, if the absorbent is heated, not only are the acidic compounds released, but the water in the absorbent also evaporates. The fluid containing these absorbents and acidic compounds becomes high-temperature.

[0026] The heating unit 30 has a heating flow path 32 for the flow of the processed liquid and a reboiler 34 disposed on the heating flow path 32. One end of the heating flow path 32 is connected to the lean liquid flow path 22, but it may also be connected to the bottom of the discharge device 14, in other words, connected to the lower end or near the lower end. The other end of the heating flow path 32 is connected to the lower part of the discharge device 14 located on the bottom side of the discharge device 14.

[0027] The reboiler 34 can be configured to heat the absorbent liquid inside the discharge device 14, but as shown in the figure, it can also be configured to heat the absorbent liquid drawn from the discharge device 14 to the outside. In addition, the reboiler 34 can be configured to heat the absorbent liquid directly or indirectly by any heat source such as electricity, steam or a burner.

[0028] The heating unit 30 is not limited to a structure that heats the absorbent liquid by means of the reboiler 34, but may also replace this structure or be equipped with a heat pump that transports the heat generated in the absorption device 12 together with the structure.

[0029] A supply path 38 is connected to the discharge device 14 to supply fluid containing acidic compounds released from the absorbent to a supply destination. Supply path 38 is a flow path for supplying the acidic compounds obtained within the discharge device 14 to the supply destination. The fluid flowing through supply path 38 contains not only the gaseous acidic compounds evaporated from the absorbent but also water vapor. A condenser 40 is provided in supply path 38 to cool this mixed gas. If the mixed gas is cooled, the water vapor condenses, thus allowing water vapor to be separated from the acidic compounds. The condenser 40 can be a heat exchanger using inexpensive cooling water such as river water. The separated water vapor is separated from the gas containing acidic compounds in a gas-liquid separator 42. If the pump 45 of the return path 44 is operated, the condensate in the gas-liquid separator 42 is returned to the discharge device 14 through the return path 44.

[0030] The discharge device 14 is connected to a rich liquid flow path 21 and a lean liquid flow path 22. The rich liquid flow path 21 is connected to the upper part of the discharge device 14, located on the top side, and introduces the absorbent liquid (rich liquid after absorbing acidic compounds) discharged from the absorption device 12 into the discharge device 14. The lean liquid flow path 22 is connected to the bottom of the discharge device 14, that is, connected to or near the lower end, so that the absorbent liquid (lean liquid after releasing acidic compounds) is discharged from the discharge device 14.

[0031] A pump 47 and a flow regulating valve 48 are provided in the rich liquid flow path 21. The pump 47 flows the absorbent liquid (rich liquid) in the absorption device 12 to the discharge device 14. The flow regulating valve 48 regulates the flow rate of the rich liquid flow path 21 in a way that allows the absorbent liquid to circulate properly between the absorption device 12 and the discharge device 14.

[0032] A pump 49 and a flow regulating valve 50 are provided in the lean liquid flow path 22. The pump 49 flows the absorbent liquid (lean liquid) in the discharge device 14 to the absorption device 12. The flow regulating valve 50 regulates the flow rate of the lean liquid flow path 22 according to the flow rate of the rich liquid flow path 21.

[0033] The multi-fluid heat exchanger 18 is connected to the rich liquid flow path 21, the lean liquid flow path 22, and the supply path 38, and is configured to heat the absorbent (rich liquid) flowing through the rich liquid flow path 21 by passing the absorbent (lean liquid) flowing through the lean liquid flow path 22 and the fluid flowing through the supply path 38. That is, the rich liquid before being introduced to the discharge device 14 is heated in the multi-fluid heat exchanger 18. In addition, the fluid flowing through the supply path 38 is a fluid containing acidic compounds that have been separated from the absorbent.

[0034] In this embodiment, the multifluid heat exchanger 18 is a plate heat exchanger. That is, in the multifluid heat exchanger 18, a plurality of plates overlap, and the gaps between adjacent plates function as flow paths for fluid inflow. Furthermore, in the multifluid heat exchanger 18, a lean liquid flow path (first high temperature flow path) 57 is provided adjacent to one side of the flow path (low temperature side flow path) 56, and a flow path (second high temperature side flow path) 58 containing the acidic compound that has separated from the absorbent is provided adjacent to the other side of the low temperature side flow path 56.

[0035] Furthermore, the multi-fluid heat exchanger 18 is not limited to plate heat exchangers, such as... Figure 2 As shown, it can also be constructed using a shell-and-tube heat exchanger. In this structure, a rich liquid flow path 21 is connected to the shell 18a to introduce the rich liquid into the shell 18a. Furthermore, a first heat transfer tube 18b and a second heat transfer tube 18c are disposed within the shell 18a. In the first heat transfer tube 18b, lean liquid is introduced from the lean liquid flow path 22, and in the second heat transfer tube 18c, a fluid containing acidic compounds that have detached from the absorbent is introduced from the supply path 38. Moreover, the rich liquid within the shell 18a is heated by the lean liquid via the first heat transfer tube 18b, and heated by the fluid containing the acidic compounds via the second heat transfer tube 18c.

[0036] The absorbent is an absorbent capable of reversibly absorbing and removing acidic compounds. For example, the absorbent is an alkaline absorbent containing water, an amine compound, and an organic solvent. The amine compound may be 30 wt%, the organic solvent 60 wt%, and the water 10 wt%.

[0037] Examples of amine compounds include: primary amines such as 2-aminoethanol (MEA) and 2-(2-aminoethoxy)ethanol (AEE); secondary amines such as 2-(methylamino)ethanol (MAE), 2-(ethylamino)ethanol (EAE), and 2-(butylamino)ethanol (BAE); or tertiary amines such as triethanolamine (TEA), N-methyldiethanolamine (MDEA), tetramethylethylenediamine (TEMED), pentamethyldiethylenetriamine (PMDETA), hexamethyltriethylenetetramine, and bis(2-dimethylaminoethyl) ether.

[0038] As organic solvents, examples include 1-butanol, 1-pentanol, octanol, diethylene glycol diethyl ether (DEGDEE), or diethylene glycol dimethyl ether (DEGDME), and multiple types can also be used in combination.

[0039] In addition, according to the paper "Hiroshi Machida et al., "Development of phase separation solution for CO2 capture by aqueous (amine+ether) solution", J. Chem. Thermodynamics 113 (2017) 64-70", if the combination of amine compounds and organic compounds is appropriately selected, it is possible to obtain an absorbent solution in which the two phases are separated into a phase with a high content of acidic compounds and a phase with a low content of acidic compounds by absorbing acidic compounds.

[0040] By appropriately selecting the combination of amine compound and organic solvent, an absorbent liquid can be formed that separates into two phases by absorbing acidic compounds: a phase with a high content of acidic compounds and a phase with a low content of acidic compounds. Furthermore, depending on the combination of amine compound and organic solvent, there are cases where the absorbent liquid does not separate into two phases even when absorbing acidic compounds, or where the absorbent liquid separates into two phases before absorbing the acidic compounds. However, in this embodiment, the absorbent liquid is not limited to an absorbent liquid that separates phases by absorbing acidic compounds.

[0041] Here, a gas processing method using the gas processing apparatus 10 according to the first embodiment will be described. The gas processing method includes an absorption step, a liquid delivery step, and a regeneration step.

[0042] The absorption process is a process in which the gas to be treated comes into contact with the absorbent liquid in the absorption unit 12. In the absorption unit 12, the gas to be treated, such as a process gas containing at least carbon dioxide, is supplied through the gas supply path 24. Furthermore, a low-temperature absorbent liquid is introduced into the absorption unit 12 through the lean liquid flow path 22 of the circulation path 16. The absorbent liquid flows down within the absorption unit 12, comes into contact with the gas to be treated, and absorbs the carbon dioxide contained in the gas. The absorption unit 12 stores the absorbent liquid that has absorbed carbon dioxide (rich liquid). When using a phase-separated absorbent liquid as the absorbent liquid, the absorbent liquid that has absorbed carbon dioxide undergoes phase separation into a first phase portion with a high carbon dioxide content and a second phase portion with a low carbon dioxide separation content.

[0043] The liquid delivery process involves transferring the absorbent (rich liquid) from the absorption unit 12 to the discharge unit 14. The absorbent is heated within the multi-fluid heat exchanger 18 by the absorbent (lean liquid) flowing through the lean liquid flow path 22 and a fluid containing acidic compounds flowing through the supply path 38, and then introduced into the discharge unit 14. Therefore, the amount of heating required in the heating section 30 of the discharge unit 14 can be reduced.

[0044] The regeneration process involves heating the absorbent introduced into the discharge device 14 to separate carbon dioxide from it. Within the discharge device 14, the absorbent is heated as it flows down. When using a phase-separated absorbent as the absorbent, the absorbent is restored to a single phase by carbon dioxide removal. The fluid containing carbon dioxide separated from the absorbent flows through the supply path 38, where the rich liquid is heated in the multi-fluid heat exchanger 18. The fluid after passing through the multi-fluid heat exchanger 18 is condensed into water vapor in the condenser 40 within the supply path 38. The water vapor is separated in the gas-liquid separator 42, thus only the carbon dioxide separated from the absorbent is supplied to the supply destination. The absorbent (lean liquid) after carbon dioxide separation in the discharge device 14 flows back to the absorption device 12 through the lean liquid flow path 22. During this process, the lean liquid heats the rich liquid flowing through the rich liquid flow path 21 in the multi-fluid heat exchanger 18, thus lowering its temperature.

[0045] As explained above, in this embodiment, in the discharge device 14, the absorbent is heated by the heating unit 30, and carbon dioxide is released from the absorbent. Therefore, the absorbent (lean liquid) and carbon dioxide become high-temperature. Through this high-temperature lean liquid and the carbon dioxide-containing fluid, the rich liquid supplied from the absorption device 12 to the discharge device 14 is heated in the multi-fluid heat exchanger 18. Therefore, the temperature of the rich liquid supplied to the discharge device 14 can be increased, thus suppressing the heat input to the heating unit 30. Furthermore, the rich liquid from the absorption device 12 does not need to be diverted to a flow path for heat exchange with the carbon dioxide-containing fluid and a flow path for heat exchange with the absorbent from the discharge device 14 before flowing into the multi-fluid heat exchanger 18. Therefore, flow regulation is not required to divert the rich liquid into a rich liquid for heat exchange with the carbon dioxide-containing fluid and a rich liquid for heat exchange with the lean liquid from the discharge device 14. Therefore, a diversion design to obtain the desired heat recovery efficiency is not required.

[0046] (Second Implementation)

[0047] Figure 3 This indicates the second embodiment of the present invention. Furthermore, the same symbols are used to denote the same components as in the first embodiment, and detailed descriptions thereof are omitted here.

[0048] In the second embodiment, a compressor 54 is provided in the supply path 38. The compressor 54 is positioned between the discharge device 14 and the multifluid heat exchanger 18 in the supply path 38. The compressor 54 compresses the gaseous fluid containing acidic compounds that flows out of the discharge device 14 and is supplied to the multifluid heat exchanger 18. Therefore, the gaseous fluid containing acidic compounds is heated before flowing into the multifluid heat exchanger 18.

[0049] Therefore, in this embodiment, since the fluid containing acidic compounds can be heated before flowing into the multifluid heat exchanger 18, the heating efficiency of the absorbent liquid supplied from the absorption device 12 to the discharge device 14 can be improved in the multifluid heat exchanger 18.

[0050] in addition, Figure 3 The example shown is a multifluid heat exchanger 18 constructed from a plate heat exchanger, but the multifluid heat exchanger 18 may also be constructed from a shell-and-tube heat exchanger. Other structures, functions, and effects are omitted from the description, but the description of the first embodiment can be referred to in the second embodiment.

[0051] (Third Implementation)

[0052] Figure 4 This indicates the third embodiment of the present invention. Furthermore, the same symbols are used to denote the same components as in the first embodiment, and detailed descriptions thereof are omitted here.

[0053] In the third embodiment, the absorption device 12 includes a tank (absorption side tank) 12a configured to store the absorbent liquid, and the discharge device 14 includes a tank (discharge side tank) 14a configured to store the absorbent liquid containing an acidic compound.

[0054] The absorber tank 12a is configured such that the absorbent liquid does not come into contact with the gas being treated while flowing down, but rather comes into contact with the gas being treated while in a stored state. Therefore, the absorber tank 12a has a shape that extends horizontally relative to the vertical direction. The absorber tank 12a is formed as a hollow structure for storing absorbent liquid, and the gas supply path 24 is connected to the absorber tank 12a at a position below the liquid surface of the absorbent liquid stored in the absorber tank 12a.

[0055] Inside the discharge side tank 14a, the absorbent liquid is not slowly heated as it flows down, but rather heated while still stored. Therefore, the discharge side tank 14a has a shape that extends horizontally relative to the vertical direction. The discharge side tank 14a is formed as a hollow structure for storing the absorbent liquid, and the heating unit 30 is positioned below the surface of the absorbent liquid stored within the discharge side tank 14a. The heating unit 30 is configured to heat the absorbent liquid stored within the discharge side tank 14a.

[0056] In the third embodiment, unlike the tower-type absorption device 12 in the first embodiment where the absorbent flows down while contacting the gas being treated, the absorption device 12 includes an absorption side tank 12a that contacts the gas being treated while storing the absorbent. Therefore, by causing the gas being treated to float in the absorbent, the absorbent is stirred. This improves the absorption efficiency of the absorbent for the gas being treated. In particular, when the absorbent is an absorbent that, after absorbing an acidic compound, separates into a phase with a high content of acidic compounds (e.g., an amine phase) and a phase with a low content of acidic compounds (e.g., an ether phase), stirring the absorbent improves the contact efficiency at the phase interface between the amine and ether phases. This makes it possible to increase the absorption efficiency of the absorbent for the gas being treated.

[0057] Furthermore, in the third embodiment, the absorbent liquid accumulated in the discharge side tank 14a is heated by the heating unit 30, and an acidic compound is released from the absorbent liquid. At this time, by releasing the acidic compound, a stirring effect can be obtained on the absorbent liquid accumulated in the discharge side tank 14a. In particular, when the absorbent liquid is an absorbent liquid that has undergone two-phase separation after absorbing the acidic compound, the flow of the absorbent liquid can increase the interfacial contact between one of the two phases (e.g., the amine phase) and the other phase (e.g., the ether phase).

[0058] In addition, in the third embodiment, the absorption device 12 has an absorption side tank 12a and the discharge device 14 has a discharge side tank 14a, but the embodiment is not limited to this structure. For example, the discharge device 14 may have a discharge side tank 14a, while the absorbent liquid in the absorption device 12 flows down and contacts the gas being treated. Furthermore, the absorption device 12 may have an absorption side tank 12a, while the absorbent liquid in the discharge device 14 is heated while flowing down. Other structures, functions, and effects are omitted from the description, but the descriptions of the first and second embodiments can be applied to the third embodiment.

[0059] (Fourth Implementation)

[0060] Figure 5 This indicates the fourth embodiment of the present invention. The fourth embodiment is based on the use of an absorbent liquid that performs two-phase separation after absorbing an acidic compound. Furthermore, the same symbols are used for the same components as in the first embodiment, and detailed descriptions thereof are omitted here.

[0061] In the third embodiment, the portion of the rich liquid flow path 21 connecting the absorption device 12 and the multifluid heat exchanger 18 is constituted by a single flow path (piping). In contrast, in the fourth embodiment, the portion of the rich liquid flow path 21 connecting the absorption device 12 and the multifluid heat exchanger 18 is constituted by two flow paths (piping) 21a and 21b. That is, the portion of the rich liquid flow path 21 connecting the absorption device 12 and the multifluid heat exchanger 18 has a first rich liquid flow path 21a and a second rich liquid flow path 21b. On the other hand, the portion of the rich liquid flow path 21 connecting the multifluid heat exchanger 18 and the discharge device 14 is constituted by a single flow path (piping).

[0062] The connection points between the first rich liquid flow path 21a and the absorption tank 12a (absorption device 12) and the second rich liquid flow path 21b and the absorption tank 12a (absorption device 12) are different in the height direction. For example, the connection point of the first rich liquid flow path 21a to the absorption tank 12a is higher than the connection point of the second rich liquid flow path 21b. On the other hand, the absorbent accumulated in the absorption tank 12a is separated into two phases by absorbing acidic compounds. The ether phase is lighter than the amine phase in the separated two phases, so the ether phase tends to accumulate at a higher position than the amine phase. Therefore, the ether phase mainly flows into the first rich liquid flow path 21a, and the amine phase mainly flows into the second rich liquid flow path 21b.

[0063] A pump 47 and a flow regulating valve 48 are respectively provided in the first rich liquid flow path 21a and the second rich liquid flow path 21b.

[0064] The multi-fluid heat exchanger 18 is composed of a plate heat exchanger, and the flow paths formed by the gaps between adjacent plates include a rich liquid flow path (low-temperature side flow path) 56, a lean liquid flow path (first high-temperature side flow path) 57, and a flow path containing a fluid containing acidic compounds that have separated from the absorbent (second high-temperature side flow path) 58. The low-temperature side flow path 56 has a first branch path 56a, where the ether phase mainly flows in through the first rich liquid flow path 21a, and a second branch path 56b, where the amine phase mainly flows in through the second rich liquid flow path 21b.

[0065] like Figure 6A As shown, the first branch path 56a and the second branch path 56b are adjacent to each other. Therefore, heat exchange sometimes occurs between the ether phase flowing into the first branch path 56a and the amine phase flowing into the second branch path 56b. That is, due to the difference in heat transfer coefficients between the ether phase and the amine phase, their heating rates are sometimes different, so in this case, heat exchange occurs between the ether phase and the amine phase. Furthermore, the difference in heating rates between the ether phase and the amine phase is also due to differences in their flow rates or specific heats.

[0066] Figure 6AThe diagram shows a structure with one first branch path 56a and one second branch path 56b, but is not limited to this. For example... Figure 6B As shown, multiple first branch paths 56a and multiple second branch paths 56b can also be formed. In this case, a header 60 is connected to the first rich liquid flow path 21a, through which the ether phase flowing through the first rich liquid flow path 21a is distributed to each of the first branch paths 56a. In addition, a header 61 is also connected to the second rich liquid flow path 21b, through which the amine phase flowing through the second rich liquid flow path 21b is distributed to each of the second branch paths 56b.

[0067] Therefore, in this embodiment, in either the first diversion path 56a or the second diversion path 56b, the absorbent from the absorption device 12 is heated by a fluid containing an acidic compound and the absorbent from the discharge device 14. At this time, a heat exchange rate corresponding to the respective flow path area can be obtained in the first diversion path 56a and the second diversion path 56b.

[0068] Furthermore, in this embodiment, even when the flow rates and physical properties of the two phases separated in the absorbent are significantly different, the complexity of the performance design of the multifluid heat exchanger 18 can be prevented. Specifically, if one of the two phases mainly flows into the first branch path 56a, the heat exchange rate in the first branch path 56a can be estimated based on the flow rate and temperature of the absorbent flowing into it. Similarly, if the other phase mainly flows into the second branch path 56b, the heat exchange rate in the second branch path 56b can be estimated based on the flow rate and temperature of the absorbent flowing into it. Therefore, the design of the multifluid heat exchanger 18 can be relatively easy.

[0069] Furthermore, in this embodiment, the connection points between the first rich liquid flow path 21a and the absorption side tank 12a (absorption device 12) and the second rich liquid flow path 21b and the absorption side tank 12a (absorption device 12) are different in the height direction. Therefore, it is possible to utilize the fact that the absorbent liquid in the absorption device 12 is stored in a state of separation into two phases, so that one of the two phases mainly flows into the first diversion path 56a, and the other phase mainly flows into the second diversion path 56b.

[0070] Furthermore, in this embodiment, since heat exchange occurs between the fluid flowing through the first diversion path 56a and the fluid flowing through the second diversion path 56b, the temperature difference between the fluid flowing through the first diversion path 56a and the fluid flowing through the second diversion path 56b can be prevented from increasing.

[0071] In this embodiment, an example of a multifluid heat exchanger 18 being constructed as a plate heat exchanger is shown, but the multifluid heat exchanger 18 may also be constructed as a shell-and-tube heat exchanger. In this case, the space within the outer casing 18a is divided into two, one space functioning as a first flow path 56a and the other space functioning as a second flow path 56b.

[0072] In the fourth embodiment, the absorption device 12 has an absorption-side tank 12a, and the discharge device 14 has a discharge-side tank 14a, but the embodiment is not limited to this structure. For example, the discharge device 14 may have a discharge-side tank 14a, while the absorption device 12 may be a structure in which the absorbent liquid flows down while contacting the gas being treated. Alternatively, the absorption device 12 may have an absorption-side tank 12a, while the discharge device 14 may be a structure in which the absorbent liquid flows down while being heated. Furthermore, the absorption device 12 may be a structure in which the absorbent liquid flows down while contacting the gas being treated, and the discharge device 14 may be a structure in which the absorbent liquid flows down while being heated. Other structures, functions, and effects are omitted from the description, but the description of the first embodiment can be applied to the second embodiment.

[0073] (Other implementation methods)

[0074] Furthermore, the embodiments disclosed herein should be considered illustrative in all respects and not intended to be limiting. The present invention is not limited to the described embodiments, and various modifications and improvements can be made without departing from its spirit. For example, the multi-fluid heat exchanger 18 may be composed of a single heat exchanger or may have a structure with multiple heat exchange sections. In the structure with multiple heat exchange sections, each heat exchange section has a low-temperature side flow path 56, a first high-temperature side flow path 57, and a second high-temperature side flow path 58. Furthermore, the low-temperature side flow path 56 in one heat exchange section functions as a first branch path 56a, and the low-temperature side flow path 56 in another heat exchange section functions as a second branch path 56b.

[0075] Here, the implementation method is described in general terms.

[0076] (1) The gas treatment apparatus according to the embodiment includes: an absorption device for receiving an absorbent liquid and absorbing acidic compounds in the gas to be treated; a discharge device for introducing the absorbent liquid that has absorbed the acidic compounds into the absorption device; a heating unit for heating the absorbent liquid in the discharge device to release the acidic compounds contained in the absorbent liquid; and a multi-fluid heat exchanger for heating the absorbent liquid supplied from the absorption device to the discharge device by passing a fluid containing the acidic compounds released from the discharge device and the absorbent liquid supplied from the discharge device to the absorption device.

[0077] In the gas treatment apparatus according to the described embodiment, in the effluent device, the absorbent is heated by a heating unit, and acidic compounds are released from the absorbent. Therefore, in the effluent device, both the absorbent and the acidic compounds become high-temperature. In the multi-fluid heat exchanger, the absorbent supplied from the absorption unit to the effluent device is heated by this high-temperature absorbent and the fluid containing the acidic compounds. Therefore, the temperature of the absorbent supplied to the effluent device can be increased, thereby suppressing the heat input to the heating unit. Furthermore, the absorbent from the absorption unit flows into the multi-fluid heat exchanger without being diverted to separate flow paths for heat exchange with the fluid containing the acidic compounds and for heat exchange with the absorbent from the effluent device. Therefore, flow regulation is unnecessary for diverting the absorbent from the absorption unit into separate flow paths for heat exchange with the fluid containing the acidic compounds and for heat exchange with the absorbent from the effluent device. Therefore, a diversion design for obtaining the desired heat recovery efficiency is not required.

[0078] (2) The multifluid heat exchanger may have: a first diversion path in which a portion of the absorbent liquid flows from the absorption device to the discharge device; and a second diversion path in which the remaining portion of the absorbent liquid flows. In this case, in the first diversion path, the portion of the absorbent liquid is heated by a fluid containing the acidic compound released from the discharge device and the absorbent liquid supplied from the discharge device to the absorption device. Furthermore, in the second diversion path, the remaining portion of the absorbent liquid is heated by a fluid containing the acidic compound released from the discharge device and the absorbent liquid supplied from the discharge device to the absorption device.

[0079] In this method, in either the first or second branch path, the absorbent from the absorption device is heated by a fluid containing an acidic compound and the absorbent from the discharge device. At this time, a heat exchange rate corresponding to the respective flow path area can be obtained in both the first and second branch paths.

[0080] (3) The absorbent can be an absorbent that has undergone two-phase separation after absorbing the acidic compound. In this case, one of the two phases of the absorbent can mainly flow into the first diversion path, and the other phase of the absorbent can mainly flow into the second diversion path.

[0081] In this approach, even when the heat transfer coefficients of one phase and the other phase differ after the absorbent is separated into two phases, the complexity of multi-fluid heat exchanger performance design can be prevented. Specifically, if one phase mainly flows into the first branch path, the heat exchange rate in the first branch path can be estimated based on the flow rate and temperature of the absorbent flowing into it. Similarly, if the other phase mainly flows into the second branch path, the heat exchange rate in the second branch path can be estimated based on the flow rate and temperature of the absorbent flowing into it. Therefore, the design of multi-fluid heat exchangers can be relatively easy. In contrast, if both phases flow into the first and second branch paths, it is difficult to estimate the heat exchange rate in each branch path without knowing the flow ratio of the two phases. This makes the design of multi-fluid heat exchangers more difficult.

[0082] (4) The absorbent liquid that has absorbed the acidic compound can be stored in the absorption device in a state of separation into two phases. In this case, the first diversion path can be connected to the absorption device through a first rich liquid flow path, and the second diversion path can be connected to the absorption device through a second rich liquid flow path that is separately provided from the first rich liquid flow path.

[0083] In this method, the absorbent liquid can be stored in the absorption device in a state of separation into two phases, so that one of the two phases mainly flows into the first diversion path, and the other phase mainly flows into the second diversion path.

[0084] (5) Heat exchange can be performed between one phase after being separated into two phases through the first diversion path and the other phase after being separated into two phases through the second diversion path, wherein the first diversion path and the second diversion path are adjacent to each other.

[0085] When the heat transfer coefficient of one phase after the absorbent is separated into two phases differs from that of the other phase, the degree of temperature rise of the fluid flowing through the first split path and the fluid flowing through the second split path may differ. In this method, since heat exchange occurs between the fluid flowing through the first split path and the fluid flowing through the second split path, the temperature difference between the fluid flowing through the first split path and the fluid flowing through the second split path can be prevented from becoming large.

[0086] (6) The multi-fluid heat exchanger can be a plate heat exchanger or a shell-and-tube heat exchanger. In this manner, a multi-fluid heat exchanger can be constructed from a general-purpose heat exchanger.

[0087] (7) The gas processing device may also include a compressor that compresses the fluid containing the acidic compound released from the venting device and supplied to the multi-fluid heat exchanger.

[0088] In this method, the fluid containing acidic compounds can be heated before flowing into the multifluid heat exchanger, thus improving the heating efficiency of the absorbent liquid supplied from the absorption device to the discharge device in the multifluid heat exchanger.

[0089] (8) The absorption device may have a tank configured to store the absorbent liquid. In this case, the gas supply path for the gas to be treated to flow into the tank may be connected to the tank at a position below the liquid level of the absorbent liquid stored in the tank.

[0090] In this method, the gas to be treated floats to the surface in the absorbent liquid, which is then stirred. Therefore, the absorption efficiency of the absorbent liquid for the gas to be treated can be improved.

[0091] (9) The discharge device may have a tank configured to store the absorbent containing the acidic compound. In this case, the heating unit may be configured to heat the absorbent containing the acidic compound and stored in the tank.

[0092] In this method, the absorbent liquid accumulated in the tank is heated by a heating element, releasing acidic compounds from the absorbent liquid. At this time, the release of acidic compounds achieves a stirring effect on the absorbent liquid accumulated in the tank. Especially when the absorbent liquid is one that has undergone two-phase separation after absorbing acidic compounds, the flow of the absorbent liquid increases the interfacial contact between one of the separated phases and the other phase.

[0093] As explained above, the required heat recovery efficiency can be achieved using lean liquid and fluid containing acidic compounds without the need for a split-flow design.

Claims

1. A gas processing device, characterized in that... include: An absorption device receives an absorbent liquid, which absorbs acidic compounds in the gas being treated. The discharging device is introduced into the absorbent liquid that has absorbed the acidic compound in the absorption device; The heating unit heats the absorbent liquid in the discharging device to release the acidic compound contained in the absorbent liquid. as well as A multi-fluid heat exchanger heats the absorbent supplied from the absorption device to the discharge device via a fluid containing the acidic compound released from the discharge device and the absorbent supplied from the discharge device to the absorption device, wherein... The absorbent is the absorbent solution used for two-phase separation after absorbing the acidic compound. The multifluid heat exchanger has: a first diversion path through which a portion of the absorbent supplied from the absorption device to the discharge device, i.e., one of the two phases after separation, mainly flows in; and a second diversion path through which the remaining portion of the absorbent supplied from the absorption device to the discharge device, i.e., the other phase after separation, mainly flows in. In the first diversion path, a portion of the absorbent is heated by a fluid containing the acidic compound released from the discharge device and the absorbent supplied from the discharge device to the absorption device. In the second diversion path, the other portion of the absorbent is heated by a fluid containing the acidic compound released from the discharge device and the absorbent supplied from the discharge device to the absorption device. The absorbent liquid, having absorbed the acidic compound, is stored in the absorption device in a state of separation as two phases. The first diversion path is connected to the absorption device via a first rich liquid flow path. The second diversion path is connected to the absorption device through a second rich liquid flow path that is separately provided from the first rich liquid flow path.

2. The gas processing device according to claim 1, characterized in that, The first and second flow paths are adjacent to each other, in a manner that heat exchange occurs between one phase after the separation into two phases in the first flow path and the other phase after the separation into two phases in the second flow path.

3. The gas processing apparatus according to claim 1 or 2, characterized in that, The multi-fluid heat exchanger is either a plate heat exchanger or a shell-and-tube heat exchanger.

4. The gas processing apparatus according to claim 1 or 2, characterized in that... Also includes: The compressor compresses the fluid containing the acidic compound released from the discharge device and supplied to the multi-fluid heat exchanger.

5. The gas processing apparatus according to claim 1 or 2, characterized in that, The absorption device has a tank configured to store the absorbent liquid. The gas supply path that allows the gas to be treated to flow into the tank is connected to the tank at a position below the liquid level of the absorbent liquid accumulated in the tank.

6. The gas processing apparatus according to claim 1 or 2, characterized in that, The discharge device has a tank configured to store the absorbent containing the acidic compound. The heating section is configured to heat the absorbent liquid containing the acidic compound and stored in the tank.

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