Gas treatment equipment

Abstract

The washing water used in the washing section is prevented from merging with the processing liquid that circulates between the absorption and regeneration processes, while enabling the removal of entrained substances accompanying the gas in the washing section. [Solution] The gas treatment apparatus 10 includes an absorber 21 that brings a gas to be treated containing an acidic compound that produces acid when dissolved in water into contact with a treatment liquid to absorb the acidic compound contained in the gas to be treated into the treatment liquid; a regenerator 22 that heats the treatment liquid that has absorbed the acidic compound to separate the acidic compound from the treatment liquid; and a washing means 35 that brings exhaust gas generated from the gas to be treated in the absorber 21 into contact with washing water to remove any accompanying substances carried in the exhaust gas. The washing means 35 is configured so that the washing water does not flow from the washing means 35 into the treatment liquid in the absorber 21.

Description

[Technical Field]

[0001] This invention relates to a gas treatment apparatus. [Background technology]

[0002] In recent years, carbon dioxide is considered to have a significant impact on global warming. As an effective measure against this global warming problem, methods for recovering CO2 from large volumes of gas containing carbon dioxide (CO2), such as exhaust gas from power plants and blast furnace by-product gases, are attracting attention. Examples of CO2 recovery methods include chemical absorption methods such as the amine absorption method. In the chemical absorption method, an alkaline aqueous solution such as an amine aqueous solution is used as the absorbent. This absorption method has a step of contacting the CO2-containing gas with the absorbent to absorb the CO2, and a regeneration step of heating the absorbent solution that has absorbed CO2 to release the CO2 from the absorbent solution, thereby recovering CO2.

[0003] In chemical absorption methods using amines, a large amount of thermal energy is required in the regeneration process to release CO2 from the amine solution that has absorbed CO2, which is one of the reasons why separation costs are high. As a method to reduce the energy required for liquid regeneration, for example, a technique is used in which heat is exchanged between the absorbent liquid (rich liquid) that flows out of the absorption tower and the absorbent liquid (lean liquid) that flows out of the desorption tower. Furthermore, examples of further energy-saving improvements have been reported, such as flushing the lean liquid and then pressurizing it to exchange heat with the rich liquid (see Patent Document 1 below).

[0004] In parallel with process development, development of processing solutions (or absorbent solutions) is also being carried out. Patent Document 2 below discloses an example of an improved solution. The processing solution disclosed in Patent Document 2 is composed of an amine, which is a chemical absorbent, an organic solvent (hereinafter referred to as ether, a typical component), which is a physical absorbent, and water. This processing solution is a homogeneous single phase before CO2 absorption, but separates into two phases, an amine phase and an ether phase, upon CO2 absorption. After the CO2 is released, it returns to a homogeneous single phase. This processing solution can be regenerated at a lower temperature (below 100°C) than typical processing solutions that are regenerated at 120°C or higher. That is, during the regeneration of the processing solution, the ether phase extracts elemental amines that are not bound to CO2 from the amine phase, making it easier for the equilibrium to shift in the direction of release, thus assisting the regeneration of the solution.

[0005] Furthermore, the need for a high-temperature heat source during the regeneration of the processed liquid contributes to the high cost of separation. Therefore, development is underway to further lower the regeneration temperature or reduce the energy required for regeneration. For example, Patent Document 3 below shows that by combining a phase separation absorbent with hydrogen stripping, the regeneration temperature can be reduced from 90°C (without stripping) to 60°C (with stripping). In hydrogen stripping, the regeneration temperature can be lowered by increasing the flow rate of hydrogen supplied to the regenerator, so the regeneration temperature can be controlled by adjusting the flow rate of stripping hydrogen.

[0006] On the other hand, Patent Documents 4 and 5 disclose the provision of a water washing section for recovering amines entrained in decarboxylated exhaust gas, which is the gas remaining after CO2 has been removed from CO2-containing exhaust gas. As shown in Figures 7 and 8, the water washing section 92 is provided within the absorber 91, above the CO2 absorption section 93. Decarboxylated exhaust gas, which is the gas from which CO2 has been absorbed into the processing liquid in the CO2 absorption section 93, flows into the water washing section 92. In the water washing section 92, the water washing water comes into contact with the decarboxylated exhaust gas, and the entrained substances entrained in the decarboxylated exhaust gas are recovered into the water washing water. This makes it possible to reduce the amount of entrained substances such as amines discharged outside the system. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2014-4525 [Patent Document 2] Patent No. 6906761 [Patent Document 3] Patent No. 6906766 [Patent Document 4] Patent No. 5968159 [Patent Document 5] Patent No. 6847760 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In Patent Documents 4 and 5, in the washing section 92, the treatment liquid entrained in the decarbonated exhaust gas, which is the gas remaining after CO2 has been removed, is recovered in the washing water, thereby reducing the amount of entrained substances discharged outside the system. However, since the washing section 92 is located above the CO2 absorption section 93 within the absorber 91, there is a risk that some of the washing water supplied to the washing section 92 may flow down from the washing section 92 and merge with the treatment liquid in the absorption process. In that case, if the treatment liquid has a low water content (for example, a treatment liquid with a water content of 30 wt% or less), an increase in the water content of the treatment liquid may affect the performance of the treatment liquid.

[0009] Therefore, the present invention has been made in view of the above-mentioned prior art, and its objective is to prevent the washing water used in the washing section from merging with the processing liquid that circulates between the absorption and regeneration processes, while enabling the removal of entrained substances accompanying the gas in the washing section. [Means for solving the problem]

[0010] A gas treatment apparatus according to one aspect of the present invention comprises: an absorber that brings a gas to be treated containing an acidic compound that produces acid upon dissolution in water into contact with a treatment liquid to absorb the acidic compound contained in the gas to be treated into the treatment liquid; a regenerator that heats the treatment liquid from which the acidic compound has been absorbed to separate the acidic compound from the treatment liquid; and a washing means that brings exhaust gas generated from the gas to be treated in the absorber into contact with washing water to remove any accompanying substances carried in the exhaust gas. The washing means is configured such that the washing water does not flow from the washing means into the treatment liquid in the absorber.

[0011] The gas treatment apparatus according to the present invention is provided with a washing means in which the exhaust gas generated from the gas to be treated is brought into contact with washing water in the absorber to remove contaminated substances accompanying the exhaust gas. As a result, the amount of contaminated substances accompanying the exhaust gas that are discharged to the outside of the gas treatment apparatus can be reduced. Moreover, the washing means is configured so that the washing water from the washing means does not mix with the treatment liquid in the absorber that is in contact with the gas to be treated. Therefore, it is possible to prevent the water content of the treatment liquid from increasing due to the washing water, and to prevent changes in the performance of the treatment liquid.

[0012] The washing means may include a washing container located outside the absorber, positioned in a gas discharge path that leads the exhaust gas from the absorber, and configured to introduce the washing water. In this case, the washing container may be configured so that the washing water introduced into the washing container does not merge with the processing liquid in the absorber.

[0013] In this embodiment, since the washing container that brings the exhaust gas and the washing water into contact with each other is located outside the absorber, it is possible to reliably prevent the washing water from merging with the treatment liquid inside the absorber.

[0014] The washing means may include a washing container disposed inside the absorber and a gas discharge passage for guiding the exhaust gas in the absorber into the washing container. In this case, the washing container may be configured to be able to introduce the washing water from the outside of the absorber, and may be configured such that the washing water after being introduced into the washing container does not merge with the treatment liquid in the absorber.

[0015] In this aspect, a washing container for bringing the exhaust gas and the washing water into contact with each other is disposed inside the absorber, and the washing container is configured such that the washing water after being introduced into the washing container does not merge with the treatment liquid in the absorber. Therefore, it is possible to reliably prevent the washing water from merging with the treatment liquid in the absorber.

[0016] A pressure boosting means configured to boost the pressure of the exhaust gas introduced into the washing container may be disposed in the gas discharge passage.

[0017] In this aspect, it is possible to condense at least a part of the accompanying substances accompanied by the exhaust gas introduced into the washing container, for example, components evaporated from the treatment liquid. Therefore, it is possible to remove at least a part of the evaporated components while suppressing the amount of washing water for removing the evaporated components contained in the exhaust gas.

[0018] The washing means may include a plurality of washing units connected in series with each other. In this aspect, it is possible to more effectively reduce the amount of the accompanying substances accompanied by the exhaust gas that is discharged to the outside of the gas treatment device.

[0019] The gas treatment device may further include a cooling means for cooling the washing water introduced into the washing means.

[0020] In this aspect, since the temperature of the exhaust gas introduced into the washing means decreases, it is possible to increase the amount of condensation of the accompanying substances accompanied by the exhaust gas, for example, components evaporated from the treatment liquid. Therefore, it is possible to remove the evaporated components while suppressing the amount of washing water for removing the evaporated components contained in the exhaust gas.

[0021] A gas treatment apparatus according to one aspect of the present invention comprises: an absorber that brings a gas to be treated containing an acidic compound that produces acid upon dissolution in water into contact with a treatment liquid to absorb the acidic compound contained in the gas to be treated into the treatment liquid; a regenerator that heats the treatment liquid from which the acidic compound has been absorbed to separate the acidic compound from the treatment liquid; and a washing means that brings a waste gas containing the acidic compound released from the treatment liquid in the regenerator into contact with washing water to remove any accompanying substances in the waste gas. The washing means is configured such that the washing water does not merge with the treatment liquid in the regenerator.

[0022] The gas treatment apparatus is equipped with a washing means that brings the exhaust gas containing acidic compounds released from the treatment liquid in the regenerator into contact with washing water to remove contaminated substances accompanying the exhaust gas. As a result, the amount of contaminated substances accompanying the exhaust gas that are discharged to the outside of the gas treatment apparatus can be reduced. Moreover, the washing means is configured so that the washing water from the washing means does not mix with the treatment liquid in the regenerator. Therefore, it is possible to prevent the water content of the treatment liquid from increasing due to the washing water, and thus prevent changes in the performance of the treatment liquid.

[0023] The washing means may include a washing container positioned outside the regenerator and configured to receive the washing water, and a supply passage connecting the regenerator and the washing container and guiding the exhaust gas from the regenerator into the washing container. In this case, the washing container may be configured so that the washing water introduced into the washing container does not merge with the processing liquid in the regenerator.

[0024] In this embodiment, since the washing container that brings the exhaust gas and washing water into contact with each other is located outside the regenerator, it is possible to reliably prevent the washing water from merging with the processing liquid inside the regenerator.

[0025] The washing means may include a washing container disposed inside the regenerator and a supply passage that guides the exhaust gas from the regenerator into the washing container. In this case, the washing container may be configured to allow the washing water to be introduced from outside the regenerator, and to prevent the washing water introduced into the washing container from merging with the processing liquid inside the regenerator.

[0026] In this embodiment, a washing container that brings exhaust gas and washing water into contact with each other is located inside the regenerator, but the washing container is configured so that the washing water introduced into the washing container does not merge with the processing liquid inside the regenerator. Therefore, it is possible to reliably prevent the washing water from merging with the processing liquid inside the regenerator.

[0027] The supply path may include a pressurizing means configured to increase the pressure of the exhaust gas introduced into the washing container.

[0028] In this embodiment, it is possible to condense at least a portion of the entrained substances carried with the exhaust gas introduced into the washing container, such as components evaporated from the treatment liquid. Therefore, at least a portion of the evaporated components can be removed while reducing the amount of washing water used to remove the evaporated components from the treatment liquid contained in the exhaust gas.

[0029] The washing means may include a plurality of washing sections connected in series with respect to each other. In this embodiment, the amount of entrained substances carried with the exhaust gas that are discharged to the outside of the gas treatment device can be reduced more effectively.

[0030] The gas treatment apparatus may further include a cooling means for cooling the washing water introduced into the washing means.

[0031] In this embodiment, the temperature of the exhaust gas introduced into the washing means is reduced, making it possible to increase the amount of condensation of entrained substances carried in the exhaust gas, such as components evaporated from the treatment liquid. Therefore, it is possible to remove evaporated components while reducing the amount of washing water used to remove them from the treatment liquid contained in the exhaust gas. [Effects of the Invention]

[0032] As described above, according to the present invention, the washing water used in the washing section can be prevented from merging with the processing liquid that circulates between the absorption and regeneration processes, while the processing liquid accompanying the gas can be recovered in the washing section. [Brief explanation of the drawing]

[0033] [Figure 1] This is a schematic diagram showing a gas treatment apparatus according to the first embodiment. [Figure 2] This figure schematically and partially shows a gas treatment apparatus according to a modified example of the first embodiment. [Figure 3] This is a schematic and partial diagram showing a gas treatment apparatus according to the second embodiment. [Figure 4] This figure schematically and partially shows a gas treatment apparatus according to a modified example of the second embodiment. [Figure 5] This is a schematic and partial diagram showing a gas treatment apparatus according to the third embodiment. [Figure 6] This figure schematically and partially shows a gas treatment apparatus according to the fourth embodiment. [Figure 7] This diagram shows a conventional gas treatment device. [Figure 8] This diagram shows a conventional gas treatment device. [Modes for carrying out the invention]

[0034] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[0035] (First Embodiment) As shown in Figure 1, the gas treatment apparatus 10 according to this embodiment is used to separate acidic compounds from a gas to be treated that contains acidic compounds using a treatment liquid. The gas treatment apparatus 10 of this embodiment targets carbon dioxide as an acidic compound. However, the acidic compound separated by the gas treatment apparatus 10 is not particularly limited as long as its aqueous solution becomes acidic, and examples include carbon dioxide and sulfur compounds. Examples of gases to be treated that contain acidic compounds include industrial exhaust gas, process gas produced during purification, and natural gas.

[0036] The gas treatment device 10 includes an absorber 21, a regenerator 22, a supply channel 25, a return channel 26, and a heat exchanger 28.

[0037] The feed channel 25 extracts the processed liquid (rich liquid) from the absorber 21 and introduces it into the regenerator 22. The feed channel 25 is connected to the lower end or near the lower end of the absorber 21. That is, one end of the feed channel 25 is connected to a position that allows the processed liquid accumulated in the absorber 21 to be extracted. The other end of the feed channel 25 is connected to the upper to central part of the regenerator 22.

[0038] The return channel 26 is a channel for extracting the processed liquid (lean liquid) from the regenerator 22 and returning it to the absorber 21. One end of the return channel 26 is connected to the lower end or near the lower end of the regenerator 22. The other end of the return channel 26 is connected to the upper end or near the upper end of the absorber 21. In other words, the return channel 26 is connected in a position that allows the processed liquid returned from the regenerator 22 to flow down from above. A pump 26a is provided in the return channel 26.

[0039] The heat exchanger 28 is connected to the feed channel 25 and the return channel 26, and facilitates heat exchange between the processing liquid flowing through the feed channel 25 and the processing liquid flowing through the return channel 26. Note that the heat exchanger 28 can be omitted.

[0040] The absorber 21 is connected to an inlet passage 31 for taking in the gas to be treated and a gas discharge passage 32 for discharging the treated gas (exhaust gas), which is the gas remaining after the acidic compounds have been absorbed into the treatment liquid. The inlet passage 31 is connected to the lower end or near the lower end of the absorber 21, and the gas discharge passage 32 is connected to the upper end or near the upper end of the absorber 21.

[0041] The absorber 21 brings the gas to be treated into contact with the treatment liquid, thereby absorbing acidic compounds in the gas into the treatment liquid, and the exhaust gas, after the acidic compounds have been removed, is discharged through the gas discharge passage 32. The absorption of acidic compounds in the absorber 21 is an exothermic reaction. The heat of this reaction generated in the absorber 21 raises the temperature of the gas to be treated and the treatment liquid.

[0042] An absorption-side condenser 34 is located in the gas discharge passage 32 to cool the exhaust gas. The absorption-side condenser 34 separates moisture from the exhaust gas by cooling it. In other words, the absorption-side condenser 34 condenses the water vapor contained in the exhaust gas and separates the moisture. The condensed water separated by the absorption-side condenser 34 is returned to the absorber 21. Note that the absorption-side condenser 34 is optional.

[0043] The gas treatment apparatus 10 includes a washing means (absorption-side washing means 35) that brings the exhaust gas generated from the gas to be treated in the absorber 21 into contact with the washing water to remove entrained substances (for example, non-aqueous components such as amine compounds released from the treatment liquid) accompanying the exhaust gas. The absorption-side washing means 35 includes a washing container 36 that is arranged in the gas discharge passage 32 and washes the exhaust gas with water. A receiving tray 36a is arranged in the middle of the washing container 36 in the height direction.

[0044] The gas discharge passage 32 is connected to a portion of the flushing container 36 below the position of the receiving tray 36a. Therefore, the space below the receiving tray 36a within the flushing container 36 becomes the introduction space 36b into which the exhaust gas is introduced.

[0045] On the other hand, the space above the receiving tray 36a is a contact space 36c for bringing the exhaust gas and the wash water into contact. That is, within the wash container 36, above the receiving tray 36a, is an outlet member 36d having an outlet for discharging the wash water. The outlet member 36d is connected to a circulation path 37 having a pump 37a. The circulation path 37 is an element of the absorption-side wash means 35. The circulation path 37 is connected to the wash container 36 so as to suck the wash water accumulated in the receiving tray 36a and send the wash water to the outlet member 36d by the pump 37a.

[0046] The receiving tray 36a is provided with a rising pipe 36e that protrudes upward, and the inside of the rising pipe 36e is in communication with the introduction space 36b. The rising pipe 36e is covered with a cap 36f having a slot. Exhaust gas introduced into the introduction space 36b flows from bottom to top into the rising pipe 36e, and this exhaust gas flows into the internal space of the cap 36f. The exhaust gas inside the internal space of the cap 36f flows to the outside of the cap 36f through the slot of the cap 36f, but since wash water is accumulated in the contact space 36c on the receiving tray 36a outside the cap 36f, the exhaust gas and the wash water come into contact with each other. The exhaust gas that comes into contact with the wash water rises through the contact space 36c above the liquid level 38 of the wash water. Note that the wash water accumulated in the receiving tray 36a does not flow into the cap 36f.

[0047] In this manner, the exhaust gas and the washing water come into contact with each other within the washing container 36, and any accompanying substances in the exhaust gas are recovered into the washing water. The washing container 36 is connected to an exhaust passage 40 that discharges the exhaust gas (treated gas), from which non-aqueous components and other accompanying substances of the treatment liquid have been removed in the contact space 36c, to the outside.

[0048] The circulation path 37 is equipped with a cooler 41, which is an example of a cooling means for cooling the wash water flowing through the circulation path 37. The cooler 41 cools the wash water introduced into the wash container 36 (washing means 35). By cooling the wash water, the temperature of the exhaust gas in contact with the wash water decreases, making it possible to increase the amount of condensation of entrained substances such as evaporated components. The cooler 41 may be placed in a wash water supply path 42 connected to the circulation path 37 instead of being placed in the circulation path 37. The supply path 42 may be used to replenish the wash water in the circulation path 37, but it is optional. The circulation path 37 may also be equipped with a drainage path 43 for discharging the wash water to the outside. Alternatively, entrained substances contained in the wash water (for example, non-aqueous components such as amine compounds released from the treatment liquid) may be separated from the wash water discharged from the contact space 36c by the circulation path 37, and the separated entrained substances may be returned to the absorption-side condenser 34. In this case, fluctuations in the amount of entrained substances contained in the treatment liquid can be suppressed.

[0049] The gas discharge passage 32 is equipped with a pressurizing means 44 configured to increase the pressure of the exhaust gas before it is introduced into the washing container 36. The pressurizing means 44 is composed of, for example, a compressor, which increases the pressure of the exhaust gas by compressing it. By increasing the pressure of the exhaust gas, it becomes possible to condense at least some of the accompanying substances (for example, evaporated components of the treatment liquid) that are carried with the exhaust gas.

[0050] The regenerator 22 is configured to store the treated liquid that has absorbed the acidic compound, and to regenerate this stored treated liquid by heating it. For this reason, the regenerator 22 has a heater 46.

[0051] The heater 46 of the regenerator 22 is configured to heat the processing liquid of the regenerator 22 using the heat of a heat source fluid. However, the heater 46 is not limited to a configuration that heats the processing liquid using a heat source fluid, but may also be configured to heat the processing liquid using a heater or the like. In Figure 1, the heater 46 is located outside the main body of the regenerator 22 and is configured to heat the processing liquid drawn out from the main body. However, the heater 46 may also be located inside the main body of the regenerator 22 and configured to heat the processing liquid within the main body.

[0052] When the processing solution is heated, acidic compounds are released from it. This release of acidic compounds from the processing solution is an endothermic reaction. In the regenerator 22, when the processing solution is heated, not only are acidic compounds released, but the water in the processing solution evaporates.

[0053] The gas treatment apparatus 10 includes a stripping means 47 that supplies a gas (hereinafter referred to as separation-promoting gas) to the regenerator 22 to promote the separation of acidic compounds from the treatment liquid. The stripping means 47 has an introduction passage 47a connected to the regenerator 22. The introduction passage 47a is connected to the lower end or near the lower end of the regenerator 22 and introduces the separation-promoting gas so that it comes into contact with the treatment liquid inside the regenerator 22. Note that the stripping means 47 is optional.

[0054] A supply line 49 is connected to the regenerator 22. The supply line 49 supplies the gas containing the acidic compound obtained from the regenerator 22 to the demand side.

[0055] A regeneration condenser 50 is located in the supply path 49. The regeneration condenser 50 cools the mixed gas of acidic compound gas evaporated from the processing liquid and water vapor. As the mixed gas cools, the water vapor condenses, allowing the regeneration condenser 50 to separate the water vapor. The separated water vapor is returned to the regenerator 22.

[0056] The separation-accelerating gas supplied to the regenerator 22 by the stripping means 47 is a gas that is almost insoluble in the processing liquid. In other words, the separation-accelerating gas is almost not absorbed by the processing liquid. Therefore, by introducing the separation-accelerating gas into the regenerator 22, the partial pressure of carbon dioxide inside the regenerator 22 can be lowered, thereby promoting the separation of carbon dioxide from the processing liquid. Examples of separation-accelerating gases include hydrocarbon gases such as hydrogen gas, oxygen gas, and methane gas, but in this embodiment, hydrogen gas is used. Note that water vapor may also be used as the separation-accelerating gas. Water vapor can dissolve in the processing liquid, but it can lower the partial pressure of carbon dioxide.

[0057] When the separation-accelerating gas is almost insoluble in the processing solution, "almost insoluble in the processing solution" may mean that its solubility in the processing solution is below a predetermined value. The separation-accelerating gas can be, for example, a gas that follows Henry's Law and has a solubility of 1 mol or less per 100 g of processing solution under conditions of 0°C and 100 kPa. Note that the solubility of oxygen in water is 1.3 × 10⁻⁶. -4 The solubility of methane in water, measured in mol / 100g, is 8 × 10⁻⁶. -4 The solubility of hydrogen in water, measured in mol / 100g, is 9.5 × 10⁻⁶. -5 The concentration is mol / 100g. In contrast, the solubility of ammonia in water is 6 mol / 100g, so ammonia does not qualify as a separation-accelerating gas.

[0058] In this embodiment, the treatment solution (absorbent) used in the gas treatment apparatus 10 is an absorbent capable of reversibly absorbing and desorbing acidic compounds. The treatment solution is, for example, 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%. The water content of the treatment solution should be adjusted to a range of, for example, 5 wt% to 30 wt%, preferably 5 wt% to 20 wt%, and more preferably 10 wt% to 20 wt%. The amine compound content may also be 20 wt% to 40 wt%.

[0059] The treatment liquid preferably undergoes phase separation by absorbing an acidic compound that generates an acid upon dissolution in water. That is, the treatment liquid preferably changes from a single-phase state to a two-phase separation state by absorbing the acidic compound, and returns to the single-phase state from the two-phase separation state by releasing the acidic compound. However, the treatment liquid is not limited to this liquid. For example, an aqueous solution of an amine compound without using an organic solvent may be used as the treatment liquid. Further, the treatment liquid may be an amine compound, an organic solvent, an ionic liquid, a mixture thereof, an aqueous solution, or the like. That is, the treatment liquid may contain water and non-aqueous components.

[0060] Examples of the amine compound include, 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 ), etc. primary amines, for example, 2-(methylamino)ethanol (MAE), 2-(ethylamino)ethanol (EAE), 2-(butylamino)ethanol (BAE), etc. secondary amines, for example, triethanolamine (TEA), N-methyldiethanolamine (MDEA), tetramethylethylenediamine (TEMED), pentamethyldiethylenetriamine (PMDETA), hexamethyltriethylenetetramine, bis(2-dimethylaminoethyl)ether, etc. tertiary amines, and the like.

[0061] Examples of the organic solvent include, 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 plurality of types may be mixed and used.

[0062] When the solubility parameters of the amine compound and the organic solvent fall within a predetermined range, the treatment solution is separated into two phases by absorption of the acidic compound: a phase with a high concentration of the acidic compound and a phase with a low concentration of the acidic compound. Here, the solubility parameter is given by the following equation (1).

[0063]

number

[0064] ΔH is the latent heat of vaporization of moles, R is the gas constant, T is the absolute temperature, and V is the molar volume.

[0065] [Table 1]

[0066] As shown in Table 1, in an absorbent containing water, an amine compound, and an organic solvent, the value obtained by subtracting the solubility parameter of the organic solvent from the solubility parameter of the amine compound is 1.1 (cal / cm³). 3 ) 1 / 2 More than 4.2(cal / cm 3 ) 1 / 2 By selecting the following combination of amine compounds and organic solvents, the absorption of acidic compounds results in two-phase separation into a phase with a high concentration of acidic compounds and a phase with a low concentration of acidic compounds. If the difference in solubility parameters is less than the lower limit, the treatment solution may not separate into two phases even if it absorbs acidic compounds. On the other hand, if the difference in solubility parameters exceeds the upper limit, the treatment solution may separate into two phases before absorbing acidic compounds, and in the step of contacting the treatment solution with the gas to be treated containing acidic compounds, the contact state between the treatment solution and the gas to be treated may become non-uniform, potentially reducing the absorption efficiency. In Table 1, "Good" means that there was a single liquid phase before carbon dioxide absorption and that it separated into two liquid phases after carbon dioxide absorption. Also, in Table 1, "Not Miscible" means that there was a two-liquid phase state before carbon dioxide absorption and that a single liquid phase was not formed. Also, in Table 1, "Not Separated" means that there was a single liquid phase even after carbon dioxide absorption.

[0067] It is desirable to set the absorption conditions in absorber 21 to a region where the processed liquid separates into two phases and a large amount of carbon dioxide dissolves, and to set the regeneration conditions in regenerator 22 to a region where the processed liquid does not separate into two phases and not much carbon dioxide dissolves. In other words, the absorption conditions and regeneration conditions are adjusted according to the partial pressure of carbon dioxide, the absorption temperature, and the regeneration temperature. This makes the processed liquid more prone to phase separation, making it possible to keep the temperature difference between the regeneration temperature and the absorption temperature lower. That is, it is possible to keep the temperature difference between the regeneration temperature and the absorption temperature low because the degree of carbon dioxide absorption changes with temperature, which changes the ease of phase separation and thus shifts the equilibrium of the carbon dioxide absorption concentration. In addition, by supplying a separation-promoting gas to regenerator 22, the temperature at which a predetermined regeneration rate can be achieved for the processed liquid (regeneration temperature) can be kept lower.

[0068] Here, a gas treatment method using the gas treatment apparatus 10 according to the first embodiment will be described. The gas treatment method includes an absorption step, a regeneration step, and a water washing step.

[0069] The absorption process involves bringing the gas to be treated into contact with the treatment liquid in the absorber 21. The gas to be treated, containing at least carbon dioxide (an acidic compound), is supplied to the absorber 21 through the inlet passage 31. The treatment liquid is also introduced into the absorber 21 through the return passage 26. The treatment liquid comes into contact with the acidic compound contained in the gas to be treated and absorbs the acidic compound. In other words, CO2 is absorbed, making it possible to recover and store carbon dioxide.

[0070] The absorber 21 stores the treatment liquid that has absorbed the acidic compound. If a phase-separating treatment liquid is used, the treatment liquid that comes into contact with the acidic compound will separate into a first phase portion with a high concentration of the acidic compound and a second phase portion with a low concentration of the acidic compound.

[0071] The processed liquid stored in the absorber 21 is sent to the regenerator 22 through the feed channel 25. At this time, the processed liquid flowing through the feed channel 25 is heated in the heat exchanger 28 by the processed liquid flowing through the return channel 26. This heated processed liquid is then introduced into the regenerator 22.

[0072] In the regenerator 22, the processing liquid is heated by the heater 46, and a separation-accelerating gas is introduced by the stripping means 47. Therefore, in the regenerator 22, acidic compounds are separated from the processing liquid in the presence of the separation-accelerating gas (regeneration process). In other words, if a separation-accelerating gas (or a separation-accelerating gas consisting of water vapor) that is almost insoluble in the processing liquid is present in the regenerator 22, the partial pressure of carbon dioxide gas in the regenerator 22 becomes low, making it easier to expel carbon dioxide (acidic compounds) from the processing liquid. Consequently, the regeneration temperature of the processing liquid in the regenerator 22 can be kept low.

[0073] The processing liquid in the regenerator 22 flows through the return channel 26 and is returned to the absorber 21. The processing liquid flowing through the return channel 26 heats the processing liquid flowing through the feed channel 25 in the heat exchanger 28.

[0074] Inside the regenerator 22, a mixed gas containing water vapor evaporated from the processing liquid and acidic compounds separated from the processing liquid is discharged from the regenerator 22 to the supply line 49. In the supply line 49, the water vapor condenses in the regeneration-side condenser 50 and is returned to the regenerator 22. The gas from which the water vapor has been removed (for example, a gas containing carbon dioxide and hydrogen) is sent to the gas consumer.

[0075] After the acidic compounds are removed by contact with the processing liquid in the absorber 21, the exhaust gas is discharged from the absorber 21 to the gas discharge passage 32. In the gas discharge passage 32, the water vapor contained in the exhaust gas is condensed in the absorption-side condenser 34 and separated from the exhaust gas. The condensed water is returned to the absorber 21.

[0076] In the gas discharge passage 32, the exhaust gas is pressurized by the pressurizing means 44. This pressurized exhaust gas is introduced into the washing container 36. The exhaust gas is introduced into the introduction space 36b in the washing container 36, flows upward through the riser pipe 36e of the receiving tray 36a, and comes into contact with the washing water accumulated on the receiving tray 36a through the slot of the cap 36f. As a result, confounding substances accompanying the exhaust gas (for example, non-aqueous components such as amine compounds released from the processing liquid) are recovered into the washing water, and the confounding substances are removed from the exhaust gas (washing process). After the confounding substances have been removed, the exhaust gas is discharged to the outside of the gas treatment device 10 through the discharge passage 40.

[0077] As described above, in this embodiment, the absorber 21 is provided with an absorption-side washing means 35 that brings the exhaust gas generated from the gas to be treated into contact with washing water to remove contaminated substances accompanying the exhaust gas. Therefore, the amount of contaminated substances accompanying the exhaust gas that are discharged to the outside of the gas treatment device 10 can be reduced. Moreover, the absorption-side washing means 35 is configured so that the washing water from the absorption-side washing means 35 does not merge with the treatment liquid in the absorber 21 that is in contact with the gas to be treated. Therefore, it is possible to prevent the water content of the treatment liquid in the absorber 21 and the regenerator 22 from increasing due to the washing water, and to prevent the performance of the treatment liquid from changing.

[0078] In addition, a washing section (not shown) may be provided in the absorber 21 or the absorber condenser 34 separately from the absorption-side washing means 35. In this case, the amount of washing water introduced into the absorber 21 can be reduced by the washing section, while the amount of evaporation of the amine compound can be suppressed. Moreover, fluctuations in the water content or amine compound content of the processed liquid in the absorber 21 and the regenerator 22 can be suppressed.

[0079] Furthermore, since the washing container 36, which brings the exhaust gas and washing water into contact with each other, is located outside the absorber 21, it is possible to reliably prevent the washing water from merging with the processing liquid inside the absorber 21.

[0080] Furthermore, since the pressurizing means 44 is located in the gas discharge passage 32, it is possible to condense at least a portion of the accompanying substances carried with the exhaust gas introduced into the washing container 36, such as components evaporated from the processing liquid. Therefore, it is possible to remove at least a portion of the evaporated components while suppressing the amount of washing water used to remove the evaporated components from the processing liquid contained in the exhaust gas.

[0081] Furthermore, since the cooler 41 is located in the circulation path 37, the temperature of the exhaust gas introduced into the washing container 36 can be reduced. This makes it possible to increase the amount of condensation of confounding substances carried in the exhaust gas, such as components evaporated from the treatment liquid. Therefore, it is possible to remove evaporated components while reducing the amount of washing water used to remove evaporated components from the treatment liquid contained in the exhaust gas.

[0082] As shown in Figure 2, the absorption-side washing means 35 may include a plurality of washing sections 35a. Each washing section 35a has a washing container 36, and the plurality of washing containers 36 are arranged in series in the gas discharge passage 32. Of the plurality of washing containers 36, the washing container 36 located on the upstream side in the direction of exhaust gas flow is referred to as the first washing container 53, and the washing container 36 located on the downstream side is referred to as the second washing container 54.

[0083] The circulation path 37 is connected to the first flushing container 53 and the second flushing container 54. Specifically, the circulation path 37 includes a first connecting path 37b that connects the contact space 36c of the first flushing container 53 to the outlet member 36d of the second flushing container 54, and a second connecting path 37c that connects the contact space 36c of the second flushing container 54 to the outlet member 36d of the first flushing container 53. Therefore, the flushing water flows between the first flushing container 53 and the second flushing container 54.

[0084] The exhaust gas discharged from the absorber 21 flows into the first wash container 53 and comes into contact with the wash water. After some of the accompanying substances have been removed from the exhaust gas in the first wash container 53, it flows into the second wash container 54 through the gas connection passage 55 and comes into contact with the wash water. After some of the accompanying substances have been removed from the exhaust gas in the second wash container 54, it is discharged to the outside of the gas treatment device 10 through the discharge passage 40.

[0085] Note that while Figure 2 includes two water-washing sections 35a, the number of water-washing sections 35a is not limited to two. Also, the boosting means 44 can be omitted. Furthermore, although the cooler 41 is located in the first connection path 37b, it may be located in the second connection path 37c, and can also be omitted.

[0086] (Second Embodiment) In the first embodiment, an absorption-side washing means 35 is provided for washing the exhaust gas discharged from the absorber 21. In the second embodiment, as shown in Figure 3, instead of the absorption-side washing means 35, a washing means (regeneration-side washing means 57) is provided in conjunction with the absorption-side washing means 35 for washing the exhaust gas containing acidic compounds released from the processing liquid in the regenerator 22. Here, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted.

[0087] The regeneration-side washing means 57 is located in the supply passage 49 and includes a washing container 58 for washing the exhaust gas. The washing container 58 has the same configuration as the washing container 36 located in the gas discharge passage 32, and the inner space of the washing container 58 is divided into an introduction space 58b and a contact space 58c by a receiving tray 58a and a cap 58f. An outlet member 58d is provided in the contact space 58c. A riser pipe 58e is provided in the receiving tray 58a.

[0088] A pressure boosting means 59, for example, consisting of a compressor, is arranged in the supply passage 49, and the exhaust gas pressurized by the pressure boosting means 59 is introduced into the introduction space 58b of the water washing container 58. Note that the pressure boosting means 59 is optional.

[0089] A circulation path 60 for circulating the wash water is connected to the wash container 58. Driven by a pump 60a, the circulation path 60 draws in the wash water accumulated on the receiving tray 58a and sends the wash water to the outlet member 58d located in the contact space 58c. A cooler 61 is provided in the circulation path 60, but the cooler 61 is optional. The circulation path 60 is a component of the regeneration wash means 57.

[0090] The exhaust gas introduced into the introduction space 36b of the washing container 58 comes into contact with the washing water in the contact space 58c, and any accompanying substances in the exhaust gas are recovered into the washing water. The exhaust gas from which the accompanying substances have been removed is sent to the gas demand destination via the supply path 49 and then through the downstream section 49a located downstream of the washing container 58.

[0091] A water supply channel 62 may be connected to the circulation channel 60. Furthermore, a drainage channel 63 for discharging the water to the outside may be connected to the circulation channel 60.

[0092] Therefore, in this embodiment, a regeneration-side washing means 57 is provided in the regenerator 22 to bring the exhaust gas containing acidic compounds released from the processing liquid into contact with washing water to remove contaminated substances accompanying the exhaust gas. As a result, the amount of contaminated substances accompanying the exhaust gas that are discharged to the outside of the gas treatment device 10 can be reduced. Moreover, the regeneration-side washing means 57 is configured so that the washing water from the regeneration-side washing means 57 does not merge with the processing liquid in the regenerator 22. Therefore, it is possible to prevent the water content of the processing liquid from increasing due to the washing water, and to prevent changes in the performance of the processing liquid.

[0093] In addition, a separate washing section (not shown) may be provided in the regenerator 22 or the regenerator condenser 50, separate from the regeneration-side washing means 57. In this case, the amount of washing water introduced into the regenerator 22 can be reduced by the washing section, while the amount of evaporation of the amine compound can be suppressed. Moreover, fluctuations in the water content or amine compound content of the processed liquid in the absorber 21 and the regenerator 22 can be suppressed.

[0094] Furthermore, since the washing container 58, which brings the exhaust gas and washing water into contact with each other, is located outside the regenerator 22, it is possible to reliably prevent the washing water from merging with the processing liquid inside the regenerator 22.

[0095] Furthermore, since the boosting means 59 is located in the supply passage 49, it is possible to condense at least a portion of the accompanying substances carried with the exhaust gas introduced into the washing container 58, such as components evaporated from the processing liquid. Therefore, it is possible to remove at least a portion of the evaporated components while suppressing the amount of washing water used to remove the evaporated components from the processing liquid contained in the exhaust gas.

[0096] Furthermore, a cooler 61 is provided to cool the exhaust gas introduced into the regeneration-side washing means 57, which makes it possible to increase the amount of condensation of entrained substances carried in the exhaust gas, such as components evaporated from the processing liquid. Therefore, it is possible to remove evaporated components while suppressing the amount of washing water used to remove evaporated components from the processing liquid contained in the exhaust gas.

[0097] As shown in Figure 4, the regeneration-side washing means 57 may include a plurality of washing sections 57a. Each washing section 57a ​​has a washing container 58, and the plurality of washing containers 58 are arranged in series in the supply passage 49. Of the plurality of washing containers 58, the washing container 58 located on the upstream side in the direction of exhaust gas flow is referred to as the first washing container 65, and the washing container 58 located on the downstream side is referred to as the second washing container 66.

[0098] The circulation path 60 is connected to the first flushing container 65 and the second flushing container 66. Specifically, the circulation path 60 includes a first connecting path 60b that connects the contact space 58c of the first flushing container 65 to the outlet member 58d of the second flushing container 66, and a second connecting path 60c that connects the contact space 58c of the second flushing container 66 to the outlet member 58d of the first flushing container 65. Therefore, the flushing water flows between the first flushing container 65 and the second flushing container 66.

[0099] The exhaust gas discharged from the regenerator 22 flows into the first wash container 65 through the supply passage 49 and comes into contact with the wash water. The exhaust gas, from which some of the accompanying substances have been removed in the first wash container 65, flows into the second wash container 66 through the gas connection passage 67 and comes into contact with the wash water. The exhaust gas, from which some of the accompanying substances have been removed in the second wash container 66, is discharged to the outside of the gas treatment device 10 through the downstream side 49a of the supply passage 49.

[0100] Note that while Figure 4 includes two water-washing sections 57a, the number of water-washing sections 57a is not limited to two. Also, the boosting means 59 is optional. Furthermore, although the cooler 61 is located in the first connection path 60b, it may be located in the second connection path 60c, and is also optional.

[0101] The other configurations, functions, and effects will not be described here, but the description of the first embodiment can be applied to the second embodiment.

[0102] (Third embodiment) In the first embodiment, the absorption-side rinsing means 35 includes a rinsing container 36 located outside the absorber 21, whereas in the third embodiment, as shown in Figure 5, the absorption-side rinsing means 35 includes a rinsing container 36 located inside the absorber 21. Note that the same reference numerals are used for components identical to those in the first and second embodiments, and their detailed descriptions are omitted.

[0103] The flushing container 36 is a sealed container located inside the absorber 21. The absorber 21 is connected to a gas discharge channel 32 that guides the exhaust gas, after the acidic compounds have been removed, into the flushing container 36. One end of the gas discharge channel 32 is connected to the absorber 21 so as to extract the exhaust gas from a portion below the flushing container 36. The other end of the gas discharge channel 32 is connected to the flushing container 36 by passing through the wall of the absorber 21 at a position corresponding to the introduction space 36b of the flushing container 36.

[0104] One end of the circulation path 37 penetrates the wall of the absorber 21 and is connected to the wash container 36 at a position corresponding to where the wash water in the wash container 36 is accumulated. The other end of the circulation path 37 penetrates the wall of the absorber 21 and is connected to the outflow member 36d of the wash container 36 at a position corresponding to the outflow member 36d of the wash container 36.

[0105] The discharge passage 40, which is connected to the flushing container 36, extends outside the absorber 21 by passing through the upper end of the absorber 21.

[0106] In this embodiment, a washing container 36 that brings exhaust gas and washing water into contact with each other is arranged inside the absorber 21. However, the washing container 36 is configured so that the washing water introduced into the washing container 36 does not merge with the processing liquid in the absorber 21. Therefore, it is possible to reliably prevent the washing water from merging with the processing liquid in the absorber 21.

[0107] The other configurations, functions, and effects will not be described here, but the descriptions of the first and second embodiments can be applied to the third embodiment.

[0108] (Fourth Embodiment) In the first embodiment, the regeneration-side rinsing means 57 includes a rinsing container 58 located outside the regenerator 22, whereas in the fourth embodiment, as shown in Figure 6, the regeneration-side rinsing means 57 includes a rinsing container 58 located inside the regenerator 22. Note that the same reference numerals are used for components identical to those in the first to third embodiments, and their detailed descriptions are omitted.

[0109] The washing container 58 is a sealed container located inside the regenerator 22. The regenerator 22 is connected to a supply passage 49 that guides exhaust gas containing acidic compounds released from the processing liquid to the washing container 58. One end of the supply passage 49 (the upstream side) is connected to the regenerator 22 so as to extract exhaust gas from a part below the washing container 58. The other end of the supply passage 49 on the upper side is connected to the washing container 58 by penetrating the wall in the regenerator 22 at a position corresponding to the introduction space 58b of the washing container 58.

[0110] One end of the circulation path 37 penetrates the wall of the regenerator 22 and connects to the washing container 58 at a position corresponding to where the washing water in the washing container 58 is accumulated. The other end of the circulation path 37 penetrates the wall of the regenerator 22 and connects to the outlet member 36d of the washing container 58 at a position corresponding to the outlet member 36d of the washing container 58.

[0111] The downstream portion 49a of the supply channel 49 connected to the washing container 58 extends outside the regenerator 22, passing through the upper end of the regenerator 22.

[0112] In this embodiment, a washing container 58 that brings exhaust gas and washing water into contact with each other is located inside the regenerator 22. However, the washing container 58 is configured so that the washing water introduced into the washing container 58 does not merge with the processing liquid in the regenerator 22. Therefore, it is possible to reliably prevent the washing water from merging with the processing liquid in the regenerator 22.

[0113] The other configurations, functions, and effects will not be described here, but the descriptions of the first to third embodiments can be applied to the fourth embodiment.

[0114] (Other embodiments) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The present invention is not limited to the embodiments described above, and various modifications and improvements are possible without departing from its spirit. For example, the absorption-side washing means 35 has a circulation path 37 and washes the exhaust gas in the washing container 36 while circulating the washing water, but the invention is not limited to this configuration. The circulation path 37 may be omitted, while a replenishment path 42 for supplying washing water to the outlet member 36d and a drainage path 43 for discharging the washing water accumulated on the receiving tray 36a may be provided. Similarly, the regeneration-side washing means 57 has a circulation path 60 and washes the exhaust gas in the washing container 58 while circulating the washing water, but the invention is not limited to this configuration. The circulation path 60 may be omitted, while a replenishment path 62 for supplying washing water to the outlet member 58d and a drainage path 63 for discharging the washing water accumulated on the receiving tray 58a may be provided. [Explanation of symbols]

[0115] 10: Gas treatment equipment 21: Absorber 22:Regenerator 32: Gas discharge channel 35: Absorption side rinsing means 35a: Washing section 36:Washing container 44: Voltage boosting means 49: Supply route 57:Regeneration side water washing means 57a: Washing section 58:Washing container 59: Voltage boosting means

Claims

1. An absorber that brings a gas to be treated containing an acidic compound that produces acid upon dissolution 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 regenerator that heats the treatment liquid that has absorbed the acidic compound and separates the acidic compound from the treatment liquid, The absorber includes a washing means that brings the exhaust gas generated from the gas to be treated into contact with the washing water to remove any entrained substances present in the exhaust gas, The washing means is configured such that the washing water does not merge from the washing means into the processing liquid in the absorber. Gas treatment device.

2. The washing means includes a washing container located outside the absorber, positioned in a gas discharge passage that leads the exhaust gas out of the absorber, and configured to introduce the washing water. The washing container is configured such that the washing water introduced into the washing container does not merge with the processing liquid in the absorber. The gas treatment apparatus according to claim 1.

3. The washing means includes a washing container disposed inside the absorber and a gas discharge passage that guides the exhaust gas from the absorber into the washing container. The washing container is configured to allow the washing water to be introduced from the outside of the absorber, and is configured so that the washing water introduced into the washing container does not merge with the processing liquid in the absorber. The gas treatment apparatus according to claim 1.

4. The gas discharge passage is equipped with a pressurizing means configured to increase the pressure of the exhaust gas introduced into the flushing container. The gas processing apparatus according to claim 2 or 3.

5. The washing means includes a plurality of washing units connected in series with respect to each other. A gas treatment apparatus according to any one of claims 1 to 3.

6. The system further comprises a cooling means for cooling the washing water introduced into the washing means. A gas treatment apparatus according to any one of claims 1 to 3.

7. An absorber that brings a gas to be treated containing an acidic compound that produces acid upon dissolution 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 regenerator that heats the treatment liquid that has absorbed the acidic compound and separates the acidic compound from the treatment liquid, The regenerator includes a washing means for bringing the exhaust gas containing acidic compounds released from the processing liquid into contact with washing water to remove entrained substances accompanying the exhaust gas, The washing means is configured such that the washing water does not merge with the processing liquid in the regenerator. Gas treatment device.

8. The washing means includes a washing container positioned outside the regenerator and configured to introduce the washing water, and a supply passage connecting the regenerator and the washing container to each other and guiding the exhaust gas from the regenerator into the washing container. The washing container is configured such that the washing water introduced into the washing container does not merge with the processing liquid in the regenerator. The gas treatment apparatus according to claim 7.

9. The washing means includes a washing container disposed inside the regenerator and a supply passage that guides the exhaust gas from the regenerator into the washing container. The washing container is configured to allow the washing water to be introduced from the outside of the regenerator, and is configured so that the washing water introduced into the washing container does not merge with the processing liquid inside the regenerator. The gas treatment apparatus according to claim 7.

10. The supply path is provided with a pressurizing means configured to increase the pressure of the exhaust gas introduced into the flushing container. The gas apparatus according to claim 8 or 9.

11. The washing means includes a plurality of washing units connected in series with respect to each other. A gas treatment apparatus according to any one of claims 7 to 9.

12. The system further comprises a cooling means for cooling the washing water introduced into the washing means. A gas treatment apparatus according to any one of claims 7 to 9.

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