Gas treatment device and gas treatment method

Abstract

To reduce energy required for separating and recovering an acidic compound.SOLUTION: A gas treatment apparatus 10 includes: an absorber 21 which brings treated gas containing an acidic compound into contact with a treatment liquid, and makes the treatment liquid absorb the acidic compound contained in the treated gas; a plurality of regenerators 22 which heat a treatment liquid absorbing the acidic compound by heat of a heat source fluid, and separate the acidic compound from the treatment liquid; and introduction means 52 for introducing separation / promotion gas of promoting separation of the acidic compound from the treatment liquid into the regenerators 22. Each of the plurality of regenerators 22 is provided with heaters 44 for heating the treatment liquid by heat of the heat source fluid. Each of the heaters 44 is connected in series and the heat source fluid is made to sequentially flow through each of the heaters 44. The introduction means 52 introduces the more separation and promotion gas into the regenerator 22 provided with the heaters positioned on the more downstream side in the flow direction of the heat source fluid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas treatment device and a gas treatment method for separating acid compounds. [Background technology]

[0002] Conventionally, gas treatment devices are known that separate acidic compounds contained in a gas to be treated by contacting the acidic compounds with a treatment liquid. For example, the gas treatment device disclosed in Patent Document 1 below includes an absorber and a regenerator. In the inhaler, the gas to be treated is brought into contact with the treatment liquid, and the acidic compounds in the gas to be treated are absorbed into the treatment liquid. Meanwhile, in the regenerator, the treatment liquid that has absorbed the acidic compounds is heated to separate the acidic compounds from the treatment liquid. When regenerating this treatment liquid, a separation-promoting gas that promotes separation of the acidic compounds is introduced into the regenerator, thereby promoting regeneration of the treatment liquid and lowering the regeneration temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6906766 Summary of the Invention [Problem to be solved by the invention]

[0004] The gas treatment device disclosed in Patent Document 1 attempts to lower the regeneration temperature and reduce the energy required for gas treatment, but there is a need to develop a technology that can separate and recover acidic compounds with less energy consumption.

[0005] Therefore, the present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to reduce the energy required for separating and recovering acidic compounds. [Means for solving the problem]

[0006] To achieve the above object, the gas treatment apparatus of the present invention includes an absorber that brings a gas to be treated, which contains acidic compounds that generate acid when dissolved in water, into contact with a treatment liquid, thereby absorbing the acidic compounds contained in the gas to be treated into the treatment liquid; a plurality of regenerators that use heat from a heat source fluid to heat the treatment liquid that has absorbed the acidic compounds and separate the acidic compounds from the treatment liquid; and an introduction means that introduces a separation-promoting gas that promotes separation of the acidic compounds from the treatment liquid into the plurality of regenerators. Each of the plurality of regenerators is provided with a heater that heats the treatment liquid with the heat of the heat source fluid, and the heaters are connected in series so that the heat source fluid flows through each heater in sequence. The introduction means is configured so that the more downstream a regenerator is provided with a heater in the flow direction of the heat source fluid, the more separation-promoting gas is introduced into it. The separation-promoting gas is hydrogen gas, oxygen gas, hydrocarbon gas, or water vapor.

[0007] In the gas treatment device according to the present invention, heaters provided for each of the multiple regenerators are arranged in series in the flow path of the heat source fluid, and the heat source fluid flows sequentially through each heater. Therefore, the heat source fluid, which has been used to heat the treatment liquid in a heater (first heater) corresponding to one regenerator (first regenerator) and whose temperature has been reduced, is introduced into a heater (second heater) corresponding to another regenerator (second regenerator). Therefore, the temperature of the treatment liquid after heating in the second heater is lower than in the first heater. On the other hand, since a larger amount of separation-promoting gas is introduced into the second regenerator corresponding to this second heater than into the first regenerator corresponding to the first heater, the second regenerator, which contains a treatment liquid at a relatively low temperature, can also be operated to separate an equivalent amount of acidic compounds from the treatment liquid as the first regenerator. Furthermore, because the heat source fluid flows sequentially through each heater, even if the treatment liquid is regenerated using multiple regenerators, it is not necessary to increase the amount of heat source fluid flowing through the heat source fluid flow path in proportion to the number of regenerators, which results in suppressing an increase in the amount of heat input. This allows the heat utilization efficiency of the entire gas treatment device to be improved, and the energy required for gas treatment to be reduced.

[0008] The treatment liquid is a treatment liquid that undergoes phase separation upon absorption of the acidic compound. Moyo In this embodiment, in the regenerator, Hydrogen gas, oxygen gas, hydrocarbons Not only is a separation-promoting gas, which is a gas or steam, brought into contact with the treatment liquid, but acidic compounds are separated from the treatment liquid with a phase having a low acidic compound content interposed between them. This allows for a lower regeneration temperature when separating acidic compounds. For example, by appropriately selecting the treatment liquid, the treatment liquid can be regenerated even at temperatures below 100°C. This also makes it possible to use normal pressure hot water or pressurized hot water as the heat source fluid. Unlike steam, hot water's temperature drops during heat exchange, but the treatment liquid temperature can also be low, making it compatible with the treatment liquid undergoing phase separation. This has the advantage of allowing the heat to be used up to a low temperature.

[0009] The gas to be treated may be carbon dioxide gas, and the separation-promoting gas may be hydrogen gas.

[0010] The gas treatment method according to the present invention includes an absorption step of contacting a gas to be treated containing acidic compounds that generate acid upon dissolution in water with a treatment liquid to absorb the acidic compounds contained in the gas to be treated into the treatment liquid, and a regeneration step of introducing the treatment liquid having absorbed the acidic compounds into a plurality of regenerators, and in each regenerator, heating the treatment liquid using heat from a heat source fluid to separate the acidic compounds from the treatment liquid. Each of the plurality of regenerators is provided with a heater, and the heaters are connected in series. The regeneration step includes a heating step of flowing the heat source fluid through each heater in sequence to heat the treatment liquid in each regenerator, and an introduction step of introducing a separation-promoting gas into each regenerator to promote separation of the acidic compounds from the treatment liquid. In the introduction step, the more downstream a regenerator equipped with a heater in the flow direction of the heat source fluid, the more separation-promoting gas is introduced. The separation-promoting gas is hydrogen gas, oxygen gas, hydrocarbon gas, or water vapor.

[0011] In the gas processing method according to the present invention, heaters provided in each of the multiple regenerators are arranged in series in the flow path of the heat source fluid, and in the heating step, the heat source fluid is passed through each heater in sequence. Therefore, the heat source fluid, which has been used to heat the treatment liquid in a heater (first heater) corresponding to one regenerator (first regenerator) and whose temperature has been reduced, is introduced into a heater (second heater) corresponding to another regenerator (second regenerator). Therefore, the temperature of the treatment liquid after heating is lowered in the second heater than in the first heater. Meanwhile, in the introduction step, a larger amount of separation-promoting gas is introduced into the second regenerator corresponding to the second heater than into the first regenerator corresponding to the first heater. Therefore, even in the second regenerator, where the treatment liquid is at a relatively low temperature, it is possible to separate an equivalent amount of acidic compounds from the treatment liquid as in the first regenerator. Furthermore, in the heating process, the heat source fluid is passed through each heater in sequence, so even if the treatment liquid is regenerated using multiple regenerators, there is no need to increase the flow rate of the heat source fluid in proportion to the number of regenerators.As a result, the increase in the amount of heat input can be suppressed, and the energy required for gas processing can be reduced.

[0012] In the gas treatment method, the treatment liquid is a treatment liquid that undergoes phase separation by absorbing the acidic compound, Moyo In this embodiment, in the regeneration step, Hydrogen gas, oxygen gas, hydrocarbons Not only is a separation-promoting gas, which is a gas or steam, brought into contact with the treatment liquid, but acidic compounds are separated from the treatment liquid with a phase having a low acidic compound content interposed between them. This allows for a lower regeneration temperature when separating acidic compounds. For example, by appropriately selecting the treatment liquid, the treatment liquid can be regenerated even at temperatures below 100°C. This also makes it possible to use normal pressure hot water or pressurized hot water as the heat source fluid. Unlike steam, hot water's temperature drops during heat exchange, but the treatment liquid temperature can also be low, making it compatible with the treatment liquid undergoing phase separation. This has the advantage of allowing the heat to be used up to a low temperature.

[0013] In the gas processing method, the gas to be processed may be carbon dioxide gas, and the separation-promoting gas may be hydrogen gas. [Effects of the Invention]

[0014] As described above, according to the present invention, it is possible to reduce the energy required for separating and recovering acidic compounds. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram schematically illustrating a configuration of a gas treatment device according to an embodiment. [Figure 2] FIG. 1 is a diagram showing the relationship between the ratio of the number of moles of carbon dioxide to the number of moles of hydrogen gas and the regeneration temperature. [Figure 3] FIG. 10 is a diagram schematically illustrating the configuration of a gas treatment device as a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] As shown in Fig. 1, a gas treatment device 10 according to an embodiment is used to separate acidic compounds from a gas to be treated that contains acidic compounds using a treatment liquid. The gas treatment device 10 of this embodiment treats carbon dioxide as an acidic compound. However, the acidic compounds separated by the gas separation device 12 are not particularly limited as long as they produce an acidic aqueous solution, and examples thereof include carbon dioxide and sulfur compounds. Examples of gas to be treated that contains acidic compounds include industrial exhaust gas, process gas generated during refining, and natural gas.

[0018] The gas processing device 10 includes an absorber 21, a plurality of regenerators 22, a feed flow path 25, a return flow path 26, and a heat exchanger 28. The feed flow path 25 extracts a treatment liquid (rich liquid) from the absorber 21 and introduces it into the plurality of regenerators 22. The feed flow path 25 includes a main flow path 25a connected to the absorber 21 and a plurality of branch flow paths 25b connected to the main flow path 25a so as to branch off from the main flow path 25a and each connected to the regenerator 22. That is, the plurality of regenerators 22 are connected to the absorber 21 in parallel with each other. The return flow path 26 extracts a treatment liquid (lean liquid) from each regenerator 22 and returns it to the absorber 21. The return flow path 26 includes a plurality of branch flow paths 26a connected to the regenerators 22, respectively, and a confluence flow path 26b where the plurality of branch flow paths 26a converge and are connected to the absorber 21.

[0019] The heat exchanger 28 is connected to the feed flow path 25 and the return flow path 26, and exchanges heat between the treatment liquid flowing through the feed flow path 25 and the treatment liquid flowing through the return flow path 26. The heat exchanger 28 may be omitted.

[0020] The absorber 21 is connected to an inlet channel 31 that takes in the gas to be treated, a gas discharge channel 32 that discharges the gas after treatment, a feed channel 25, and a return channel 26. The inlet channel 31 is connected to the lower end of the absorber 21, and the gas discharge channel 32 is connected to the upper end of the absorber 21. A main channel 25a of the feed channel 25 is connected to the lower end or near the lower end of the absorber 21. That is, the feed channel 25 is connected to a position where the treated liquid accumulated in the absorber 21 can be discharged. A junction channel 26b of the return channel 26 is connected to the upper end or near the upper end of the absorber 21. That is, the return channel 26 is connected to a position where the treated liquid returned from the regenerator 22 can flow downward from above.

[0021] The absorber 21 brings the gas to be treated into contact with the treatment liquid, thereby absorbing the acidic compounds in the gas to be treated into the treatment liquid, and discharges the gas from which the acidic compounds have been removed. The absorption of the acidic compounds in the absorber 21 is an exothermic reaction. The heat of reaction generated in the absorber 21 increases the temperatures of the gas to be treated and the treatment liquid.

[0022] A branch flow path 25b of the feed flow path 25 and a subflow path 26a of the return flow path 26 are connected to each regenerator 22. The branch flow path 25b of the feed flow path 25 is connected to the area from the top to the center of the regenerator 22. The subflow path 26a of the return flow path 26 is connected to the lower end or near the lower end of the regenerator 22. A pump 36 is provided in the confluence flow path 26b of the return flow path 26.

[0023] Each regenerator 22 stores the treatment liquid that has absorbed the acidic compounds, and heats the stored treatment liquid to desorb the acidic compounds from the treatment liquid. The desorption of the acidic compounds from the treatment liquid is an endothermic reaction. In each regenerator 22, when the treatment liquid is heated, not only are the acidic compounds desorbed, but water in the treatment liquid also evaporates.

[0024] A heating flow path 40 and a supply path 42 are connected to each regenerator 22. The heating flow path 40 is provided with a heater 44 for heating the treatment liquid that flows out from the bottom of the regenerator 22, and returns the heated treatment liquid to the bottom of the regenerator 22. The heater 44 is configured to heat the treatment liquid that flows out from the regenerator 22 using the heat of a heat source fluid. The heat source fluid is, for example, hot water at 100°C or less, but a heat medium or steam may also be used.

[0025] The heat source fluid is supplied to the heaters 44 through a fluid flow path 46. The fluid flow path 46 is connected to each heater 44 so as to connect the heaters 44 in series. The fluid flow path 46 first supplies the heat source fluid supplied from a supply source not shown to the heater 44 on the right side of the figure, and then supplies the heat source fluid that has passed through this heater 44 to the heater 44 on the left side of the figure. In FIG. 1, the heater 44 provided in the regenerator 22 on the right side (first regenerator 22A) functions as the first heater 44A, and the heater 44 provided in the regenerator 22 on the left side (second regenerator 22B) functions as the second heater 44B. Therefore, the temperature of the heat source fluid passing through the second heater 44B is lower than the temperature of the heat source fluid passing through the first heater 44A.

[0026] The supply line 42 supplies the gas containing the acid compounds obtained in the regenerator 22 to the demand side. The supply line 42 is provided with a condenser 50 for cooling a mixed gas of water vapor and the gas containing the acid compounds evaporated from the treated liquid. When the mixed gas is cooled, the water vapor condenses, and the water vapor can be separated by the condenser 50. The separated water vapor is returned to the regenerator 22. A heat exchanger using inexpensive cooling water such as river water can be used as the condenser 50. Note that the supply line 42 is configured to combine the gases flowing out from each regenerator 22 before supplying them to the demand side. However, instead, the supply line 42 may be configured to separately supply the gases flowing out from each regenerator 22 to the demand side. This is effective when the composition ratios of the gases regenerated in each regenerator 22 are different.

[0027] The gas treatment device 10 is provided with an introduction means 52 that supplies a gas for promoting separation of acidic compounds (hereinafter referred to as a separation promoting gas) to each regenerator 22. The introduction means 52 has a plurality of introduction paths 52a for feeding the separation promoting gas into the plurality of regenerators 22, and a flow rate adjustment unit 52b that varies the flow rate of the separation promoting gas supplied through each introduction path 52a. The downstream end of each introduction path 52a is connected to the lower end, near the lower end, or heating flow path of the regenerator 22. Note that the plurality of introduction paths 52a are flow paths configured to branch off from a single gas supply source, but may also be configured as separate flow paths connected to different gas supply sources.

[0028] The flow rate adjusting unit 52b can adjust the flow rate of each inlet passage 52a so that a larger amount of separation promoting gas is introduced into the regenerator 22 (second regenerator 22B) provided with the heater 44 (second heater 44B) located downstream in the flow direction of the heat source fluid in the heating flow passage 40. The flow rate adjusting unit 52b may be configured by a flow rate adjusting valve arranged in each inlet passage 52a.

[0029] 1, the temperature of the left heater 44 (second heater 44B) is lower than the temperature of the right heater 44 (first heater 44A), so the flow rate adjuster 52b adjusts the flow rate of each introduction path 52a so that the flow rate of the separation promoting gas supplied to the left regenerator 22 (second regenerator 22B) is higher than the flow rate of the separation promoting gas supplied to the right regenerator 22 (first regenerator 22A). In other words, more separation promoting gas is supplied to the second regenerator 22B, which has a relatively low temperature, than to the first regenerator 22A, which has a relatively high temperature.

[0030] The separation-promoting gas supplied to the regenerator 22 by the introducing means 52 is a gas that is almost insoluble in the treatment liquid. In other words, the separation-promoting gas is almost not absorbed by the treatment liquid. Therefore, by introducing the separation-promoting gas into the regenerator 22, the partial pressure of carbon dioxide in the regenerator 22 can be lowered, thereby promoting the separation of carbon dioxide from the treatment liquid. Examples of the separation-promoting gas include hydrocarbon gases such as hydrogen gas, oxygen gas, and methane gas, but hydrogen gas is used in this embodiment. Note that water vapor may also be used as the separation-promoting gas. Water vapor can dissolve in the treatment liquid, but it can also lower the partial pressure of carbon dioxide.

[0031] When the separation-promoting gas is almost insoluble in the treatment liquid, the phrase "almost insoluble in the treatment liquid" may mean that the solubility in the treatment liquid is equal to or less than a predetermined value. The separation-promoting gas may be, for example, a gas that follows Henry's law and has a solubility of 1 mol or less in 100 g of treatment liquid under conditions of 0°C and 100 kPa. The solubility of oxygen in water is 1.3 x 10 -4 mol / 100g, the solubility of methane in water is 8 x 10 -4 mol / 100g, the solubility of hydrogen in water is 9.5 x 10 -5 In contrast, the solubility of ammonia in water is 6 mol / 100 g, so ammonia does not qualify as a separation-promoting gas.

[0032] In this embodiment, the treatment liquid (absorbent) used in the gas treatment device 10 is an absorbent capable of reversibly absorbing and desorbing acidic compounds. The treatment liquid may be, for example, an alkaline absorbent containing water, an amine compound, and an organic solvent. The amine compound may be 30 wt %, the organic solvent may be 60 wt %, and the water may be 10 wt %. The treatment liquid preferably undergoes phase separation by absorbing an acidic compound that generates an acid when dissolved in water, but this is not limited to this. For example, the treatment liquid may be an aqueous solution of an amine compound without using an organic solvent. The treatment liquid may also be an amine compound, an organic solvent, an ionic liquid, a mixture thereof, an aqueous solution, or the like.

[0033] As the amine compound, for example, 2-aminoethanol (MEA: solubility parameter = 14.3 (cal / cm 3 ) 1 / 2 ), 2-(2-aminoethoxy)ethanol (AEE: solubility parameter = 12.7 (cal / cm 3 ) 1 / 2 ), secondary amines such as 2-(methylamino)ethanol (MAE), 2-(ethylamino)ethanol (EAE), and 2-(butylamino)ethanol (BAE), and tertiary amines such as triethanolamine (TEA), N-methyldiethanolamine (MDEA), tetramethylethylenediamine (TEMED), pentamethyldiethylenetriamine (PMDETA), hexamethyltriethylenetetramine, and bis(2-dimethylaminoethyl)ether.

[0034] As an organic solvent, for example, 1-butanol (solubility parameter = 11.3 (cal / cm 3 ) 1 / 2 ), 1-pentanol (solubility parameter = 11.0 (cal / cm 3 ) 1 / 2 ), octanol, diethylene glycol diethyl ether (DEGDEE), diethylene glycol dimethyl ether (DEGDME), etc., and a mixture of two or more kinds may be used.

[0035] When the solubility parameters of the amine compound and the organic solvent are within a predetermined range, the treatment solution is separated into two phases, one with a high acidic compound content and the other with a low acidic compound content, due to absorption of the acidic compound. Here, the solubility parameter is expressed by the following formula (1):

[0036]

number

[0037] [Table 1] As shown in Table 1, in an absorbent containing water, an amine compound, and an organic solvent, the solubility parameter of the amine compound minus the solubility parameter of the organic solvent is 1.1 (cal / cm 3 ) 1 / 2 More than 4.2(cal / cm 3 ) 1 / 2 By selecting the combination of amine compound and organic solvent as shown below, absorption of an acidic compound results in two-phase separation into a phase with a high acidic compound content and a phase with a low acidic compound content. If the difference in solubility parameters is less than the lower limit, the treatment liquid may not separate into two phases even after absorbing the acidic compound. On the other hand, if the difference in solubility parameters exceeds the upper limit, the treatment liquid may separate into two phases before absorbing the acidic compound. In the step of contacting the treatment liquid with a gas to be treated containing the acidic compound, the contact state between the treatment liquid and the gas to be treated may become uneven, resulting in a decrease in absorption efficiency. Note that "good" in Table 1 means that the mixture was in a single liquid phase before carbon dioxide absorption and separated into two liquid phases upon carbon dioxide absorption. Also, "immiscible" in Table 1 means that the mixture was in a two-liquid phase state before carbon dioxide absorption and did not form a single liquid phase. Also, "no separation" in Table 1 means that the mixture remained in a single liquid phase even after carbon dioxide absorption.

[0038] It is desirable to set the absorption conditions in the absorber 21 to a range in which the treated liquid separates into two phases and dissolves a large amount of carbon dioxide, and to set the regeneration conditions in the regenerator 22 to a range in which the treated liquid does not separate into two phases and dissolves little carbon dioxide. That is, the absorption conditions and regeneration conditions are adjusted according to the carbon dioxide partial pressure, absorption temperature, and regeneration temperature. This facilitates phase separation in the treated liquid, making it possible to keep the temperature difference between the regeneration temperature and the absorption temperature low. That is, this system utilizes the fact that the degree of carbon dioxide absorption changes depending on the temperature, which changes the ease of phase separation and shifts the equilibrium of the carbon dioxide absorption concentration, making it possible to keep the temperature difference between the regeneration temperature and the absorption temperature low. In addition, because a separation-promoting gas is supplied to the regenerator 22, the regeneration temperature can be kept even lower.

[0039] Here, a gas processing method using the gas processing device 10 according to the first embodiment will be described. The gas processing method includes an absorption step and a regeneration step.

[0040] The absorption step is a step in which the gas to be treated is brought into contact with a treatment liquid in the absorber 21. The gas to be treated, which contains at least carbon dioxide, is supplied to the absorber 21 through the inlet line 31. The treatment liquid is also introduced into the absorber 21 through the return line 26. The treatment liquid comes into contact with the carbon dioxide contained in the gas to be treated and absorbs the carbon dioxide. The treatment liquid that has absorbed carbon dioxide is stored in the absorber 21. When a treatment liquid that undergoes phase separation is used, the treatment liquid that comes into contact with 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 content.

[0041] The treated liquid stored in the absorber 21 is sent to the regenerators 22 through the feed flow path 25. At this time, the treated liquid flowing through the feed flow path 25 is heated in the heat exchanger 28 by the treated liquid flowing through the return flow path 26, and then divided and introduced into each regenerator 22.

[0042] The regeneration step is a step in which the treatment liquid introduced into the regenerator 22 is heated while a separation-promoting gas is supplied to the regenerator 22 to promote the separation of carbon dioxide and separate carbon dioxide from the treatment liquid.

[0043] Specifically, in the regeneration step, a heat source fluid is supplied to each heater 44 through the fluid flow path 46, and this heat source fluid flows sequentially through each heater 44 to heat the treatment liquid in each regenerator 22 (heating step). The heat source fluid is supplied from a supply source (not shown) and passes through the first heater 44A. After passing through the first heater 44A, the heat source fluid passes through the second heater 44B. For example, when a heat source fluid at 100°C is supplied from the supply source, the first heater 44A heats the treatment liquid, lowering its temperature from 100°C to 90°C, and the second heater 44B heats the treatment liquid, lowering its temperature from 90°C to 80°C. In other words, the first heater 44A supplies sensible heat of 10°C to the treatment liquid, and the second heater 44B also supplies sensible heat of 10°C to the treatment liquid, so that a total of 20°C of sensible heat can be used to heat the treatment liquid. In this case, the temperature of the treatment liquid returning from the first heater 44A to the first regenerator 22A is, for example, 80° C., and the temperature of the treatment liquid returning from the second heater 44B to the second regenerator 22B is, for example, 70° C. In other words, each heater 44 is operated under the constraint that the temperature difference between the temperature of the outflowing heat source fluid and the temperature of the outflowing treatment liquid is 10° C.

[0044] A separation-promoting gas that promotes the separation of carbon dioxide from the treatment liquid is introduced into each regenerator 22 (introduction step). The flow rates of the introduction paths 52a are adjusted so that the flow rate of the separation-promoting gas supplied to the second regenerator 22B is greater than the flow rate of the separation-promoting gas supplied to the first regenerator 22A. Therefore, even if the set temperature of the second regenerator 22B is lower than that of the first regenerator 22A, the second regenerator 22B can produce the same amount of carbon dioxide gas as the first regenerator 22A. In other words, if a larger amount of separation-promoting gas that is substantially insoluble in the treatment liquid is present in the regenerator 22, the partial pressure of carbon dioxide gas in the regenerator 22 decreases, making it easier to expel carbon dioxide from the treatment liquid. Therefore, as shown in FIG. 2, the regeneration temperature decreases as the ratio of the number of moles of carbon dioxide to the number of moles of hydrogen gas increases. Therefore, even if the temperature of the treatment liquid is low, increasing the flow rate of the separation-promoting gas can prevent a decrease in the amount of carbon dioxide gas produced.

[0045] At this time, the first regenerator 22A is set to 80°C, so the molar ratio of hydrogen gas to carbon dioxide gas generated per unit time is approximately 1:2, and the second regenerator 22B is set to 70°C, so the molar ratio of hydrogen gas to carbon dioxide gas generated per unit time is approximately 2:2. Therefore, the composition ratio of the gas obtained from the first regenerator 22A and the second regenerator 22B is different. In this case, in the mixed gas obtained by mixing the mixed gas supplied from the first regenerator 22A and the mixed gas supplied from the second regenerator 22B, the molar ratio of hydrogen gas to carbon dioxide gas generated per unit time is approximately 3:4.

[0046] When the treated liquid is heated in each regenerator 22, water vapor may be evaporated from the treated liquid. The carbon dioxide and water vapor separated from the treated liquid flow through the supply path 42. In the supply path 42, the water vapor is condensed in the condenser 50 and returned to the regenerator 22. The treated liquid stored in the regenerator 22 flows through the return path 26 and returns to the absorber 21.

[0047] Here, referring to Figure 3, a gas treatment device provided with one regenerator 22 will be described as a comparative example. This gas treatment device as a comparative example is configured with one regenerator 22 as shown in Figure 3. However, when a heat source fluid at 100°C is supplied to the heater 44 from a supply source, in order to ensure that the molar ratio of hydrogen gas to carbon dioxide gas generated per unit time is approximately 3:4, as in the gas treatment device 10 of Figure 1, the temperature of the treatment liquid heated by the heater 44 needs to be set to approximately 75°C. In other words, a temperature setting of 70°C results in a mixed gas with a molar ratio of hydrogen gas to carbon dioxide gas of approximately 2:2, and a temperature setting of 80°C results in a mixed gas with a molar ratio of hydrogen gas to carbon dioxide gas of approximately 1:2. Therefore, in order to obtain a mixed gas with a molar ratio of approximately 3:4, the set temperature of the heater 44 needs to be set to approximately 75°C. In this case, considering the same constraint as that of the heater 44 in FIG. 1, i.e., the constraint that the temperature difference between the temperature of the heat source fluid flowing out of the heater 44 and the temperature of the treatment liquid flowing out of the heater 44 is 10°C, the temperature of the heat source fluid after passing through the heater 44 will be controlled to 85°C. In other words, the heater 44 will utilize sensible heat of 100°C - 85°C = 15°C. Therefore, the gas treatment device in FIG. 3 has lower heat utilization efficiency than the gas treatment device 10 in FIG. 1, which can utilize sensible heat of 20°C. This shows that the gas treatment device 10 in FIG. 1 has improved thermal efficiency compared to a configuration provided with one regenerator 22.

[0048] As described above, in this embodiment, the heaters 44 provided in each of the multiple regenerators 22 are arranged in series in the fluid flow path 46, and the heat source fluid flows sequentially through each heater 44. Therefore, the heat source fluid, which has been used to heat the treatment liquid in the first heater 44A corresponding to the first regenerator 22A and whose temperature has been reduced, is introduced into the second heater 44B corresponding to the second regenerator 22B. Therefore, the temperature of the treatment liquid after heating in the second heater 44B is lower than that in the first heater 44A. On the other hand, since a larger amount of separation-promoting gas is introduced into the second regenerator 22B corresponding to the second heater 44B than into the first regenerator 22A corresponding to the first heater 44A, the second regenerator 22B, which contains a treatment liquid at a relatively low temperature, can also be operated to separate an amount of acidic compounds from the treatment liquid equivalent to that of the first regenerator 22A. Moreover, because the heat source fluid flows sequentially through each heater 44 along the fluid flow path 46, even if the treatment liquid is regenerated in multiple regenerators 22, it is not necessary to increase the amount of heat source fluid flowing through the heat source fluid flow path in proportion to the number of regenerators 22, and as a result, it is possible to suppress an increase in the amount of heat input. Therefore, the heat utilization efficiency of the gas treatment device 10 as a whole can be improved, and the energy required for gas treatment can be reduced.

[0049] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The present invention is not limited to the above-described embodiments, and various modifications and improvements are possible without departing from the spirit of the present invention. For example, although two regenerators 22 are provided in the gas treatment device 10 of the above-described embodiment, three or more regenerators may be provided. Even in this case, the heat source fluid flows sequentially through each heater 44 along the fluid flow path 46, and the introduction means 52 is configured to introduce a larger amount of separation-promoting gas into the regenerator 22 provided with the heater 44 located downstream in the flow direction of the heat source fluid. [Explanation of symbols]

[0050] 10: Gas treatment equipment 21: Absorber 22: Regenerator 22A: First regenerator 22B: Second regenerator 44: Heater 44A: First heater 44B: Second heater 46: Fluid flow path 52: Introduction method 52a:Introduction path 52b:Flow rate adjustment section

Claims

1. an absorber that brings a gas to be treated, which contains an acidic compound that generates an acid when dissolved in water, into contact with a treatment liquid, thereby absorbing the acidic compound contained in the gas to be treated into the treatment liquid; a plurality of regenerators that heat the treatment liquid that has absorbed the acidic compounds by utilizing heat from a heat source fluid and separate the acidic compounds from the treatment liquid; an introducing means for introducing a separation promoting gas that promotes separation of the acid compounds from the treatment liquid into the plurality of regenerators; Equipped with each of the plurality of regenerators is provided with a heater that heats the treatment liquid with heat from the heat source fluid, and the heaters are connected in series so that the heat source fluid flows through each heater in sequence; the introducing means is configured to introduce a larger amount of the separation promoting gas into a regenerator provided with a heater located downstream in a flow direction of the heat source fluid, The separation-promoting gas is hydrogen gas, oxygen gas, hydrocarbon gas, or water vapor. Gas treatment equipment.

2. The gas treatment device according to claim 1 , wherein the treatment liquid undergoes phase separation upon absorption of the acidic compound.

3. 3. The gas treatment apparatus according to claim 1, wherein the gas to be treated is carbon dioxide gas, and the separation promoting gas is hydrogen gas.

4. an absorption step of bringing a gas to be treated, which contains an acidic compound that generates an acid when dissolved in water, into contact with a treatment liquid, thereby absorbing the acidic compound contained in the gas to be treated into the treatment liquid; a regeneration step of introducing the treatment liquid having absorbed the acidic compounds into a plurality of regenerators, heating the treatment liquid in each regenerator using heat from a heat source fluid, and separating the acidic compounds from the treatment liquid, a heater is provided in each of the plurality of regenerators, and the heaters are connected in series; The regeneration step includes: a heating step of heating the treated liquid in each regenerator by passing the heat source fluid through each heater in turn; an introducing step of introducing a separation promoting gas into each regenerator, the separation promoting gas promoting separation of the acidic compounds from the treatment liquid; In the introducing step, a larger amount of the separation promoting gas is introduced into a regenerator provided with a heater that is located downstream in a flow direction of the heat source fluid, The gas processing method, wherein the separation-promoting gas is hydrogen gas, oxygen gas, hydrocarbon gas, or water vapor.

5. The gas treatment method according to claim 4 , wherein the treatment liquid undergoes phase separation upon absorption of the acidic compound.

6. 6. The gas processing method according to claim 4, wherein the gas to be processed is carbon dioxide gas, and the separation-promoting gas is hydrogen gas.

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