Gas separation device and gas separation method

Abstract

This gas separation device comprises: a combustion device having a boiler; a steam turbine into which steam obtained in the boiler is introduced; an absorber that brings a gas to be treated, which is discharged from the combustion device and contains an acidic compound, into contact with a treatment liquid to cause the acidic compound to be absorbed by the treatment liquid; a steam condenser into which outlet steam from the steam turbine is introduced; and a regenerator in which the steam condenser is disposed and into which the treatment liquid that has absorbed the acidic compound is introduced. In the regenerator, the treatment liquid is heated by the heat of the outlet steam while the outlet steam flowing through the steam condenser is condensed, and the acidic compound is separated from the treatment liquid heated in the regenerator.

Description

Gas separation apparatus and gas separation method

[0001] The present invention relates to a gas separation apparatus and a gas separation method.

[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, a technology that separates acidic compounds by bringing a gas containing acidic compounds into contact with an absorbent liquid is attracting attention. Gas separation devices utilizing this type of separation technology are disclosed in Patent Documents 1 to 4.

[0003] As shown in Figure 10, the gas separation apparatus disclosed in Patent Document 1 comprises an absorption unit 81, a desorption unit 82, and a circulation path 83 for circulating the processed liquid between the absorption unit 81 and the desorption unit 82. Exhaust gas from the combustion device 84 is introduced into the absorption unit 81. Inside the absorption unit 81, the exhaust gas comes into contact with the processed liquid, and the acidic compounds contained in the exhaust gas are absorbed into the processed liquid. The processed liquid that has absorbed the acidic compounds is introduced into the desorption unit 82. The desorption unit 82 is equipped with a heating device 86 that introduces extracted steam from the intermediate stage of the steam turbine 85 to heat the processed liquid. In the desorption unit 82, the processed liquid is heated by the heat of the extracted steam, and the acidic compounds are released. The outlet steam from the steam turbine 85 is supplied to the condenser 87 for cooling.

[0004] In the gas separation apparatus disclosed in Patent Document 2, as shown in Figure 11, a steam extraction line 92 is connected to the combustion equipment 91, and steam is introduced into the regenerative heater 93 through this steam extraction line 92, heating the processing liquid in the regenerative heater 93. In this gas separation apparatus, the temperature of the condensate returned from the regenerative heater 93 to the combustion equipment 91 is 100°C. Therefore, it is presumed that in this gas separation apparatus as well, the extracted gas from the turbine contained in the combustion equipment 91 is introduced into the regenerative heater 93 through the steam extraction line 92.

[0005] Patent documents 3 and 4 disclose gas treatment devices that achieve energy savings by using a low-temperature regenerative treatment liquid. Patent document 3 discloses that a regeneration temperature of 100°C or lower can be achieved by using a treatment liquid that separates into two phases, a phase with a high CO2 content and a phase with a low CO2 content, through CO2 absorption. The treatment liquid is an alkaline liquid containing water, an amine compound, and an organic solvent. Patent document 4 discloses that the regeneration temperature can be further reduced by supplying a separation-promoting gas, which is a gas that is almost insoluble in the treatment liquid and consists of a hydrocarbon gas such as methane, hydrogen gas, or oxygen gas, during the regeneration process. Lowering the regeneration temperature will contribute to the widespread adoption of CO2 separation technology and will be effective as a measure against global warming.

[0006] In the gas separation apparatus disclosed in Patent Documents 1 and 2, the treatment liquid is heated and regenerated using steam extracted from the turbine, resulting in a high heating capacity for the treatment liquid. However, because steam is extracted from the intermediate stage of the turbine, the power generation capacity of the turbine is reduced. On the other hand, Patent Documents 3 and 4 disclose technologies that aim to save energy by lowering the regeneration temperature, but even if these technologies are applied to the gas separation apparatus disclosed in Patent Documents 1 and 2, the problem of reduced power generation capacity still remains.

[0007] Japanese Patent Publication No. 5465246, Japanese Unexamined Patent Publication No. 2011-173047, Japanese Patent Publication No. 6906761, Japanese Patent Publication No. 6906766

[0008] The objective of this invention is to enable the regeneration of the treatment fluid while suppressing a decrease in the power generation capacity of the turbine.

[0009] A gas separation apparatus according to one aspect of the present invention comprises a combustion apparatus having a boiler; a steam turbine into which steam obtained from the boiler is introduced; an absorber configured to bring a gas to be treated, which is discharged from the combustion apparatus and contains an acidic compound that produces acid when dissolved in water, into contact with a processing liquid, and to allow the acidic compound contained in the gas to be treated to be absorbed into the processing liquid; a steam condenser into which the outlet steam from the steam turbine is introduced; and a regenerator into which the steam condenser is located and the processing liquid from which the acidic compound has been absorbed is introduced. The regenerator is configured to heat the processing liquid by the heat of the outlet steam as the outlet steam flowing through the steam condenser condenses, and the acidic compound is separated from the processing liquid heated in the regenerator.

[0010] A gas separation method according to another aspect of the present invention involves discharging a gas to be treated containing an acidic compound that produces acid when dissolved in water from a combustion device; introducing the gas to be treated discharged from the combustion device into an absorber and bringing it into contact with a treatment liquid to absorb the acidic compound contained in the gas to be treated into the treatment liquid; introducing the steam obtained from the boiler of the combustion device into a steam turbine to generate electricity; introducing the outlet steam from the steam turbine into a steam condenser; and in a regenerator where the steam condenser is located, heating the treatment liquid that has absorbed the acidic compound with the outlet steam, and separating the acidic compound from the treatment liquid while condensing the outlet steam.

[0011] This is a schematic diagram showing the configuration of a gas separation device according to the first embodiment. This is a schematic diagram showing the configuration of a gas separation device according to the second embodiment. This is a schematic diagram showing the configuration of a gas separation device according to a modified example of the second embodiment. This is a schematic diagram showing the configuration of a gas separation device according to a modified example of the first embodiment. This is a schematic diagram showing the configuration of a gas separation device according to the third embodiment. This is a diagram for explaining the condenser and separator provided in the gas separation device. This is a diagram for explaining the gas separation method performed by the gas separation device according to the third embodiment. This is a schematic diagram showing the configuration of a gas separation device according to the fourth embodiment. This is a diagram for explaining the gas separation method performed by the gas separation device according to the fourth embodiment. This is a diagram of a conventional gas separation device. This is a diagram of a conventional gas separation device.

[0012] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[0013] (First Embodiment) As shown in Figure 1, the gas separation apparatus 10 according to this embodiment comprises a combustion device 12, a steam turbine 14, an absorber 16, and a regenerator 18, and is configured to separate acidic compounds contained in the exhaust gas (gas to be treated) discharged from the combustion device 12 from the exhaust gas in the absorber 16 and the regenerator 18. The acidic compounds are not particularly limited as long as their aqueous solution produces acid, and examples include carbon dioxide (CO2) and sulfur compounds.

[0014] The combustion apparatus 12 includes a combustion furnace 12a for burning fuel and a boiler 12b that heats water with the exhaust gas produced in the combustion furnace 12a to generate steam. In the combustion furnace 12a, fuel is burned, which produces high-temperature exhaust gas. In the boiler 12b, water is heated by the heat of this exhaust gas to generate steam.

[0015] The steam turbine 14 is connected to the boiler 12b via a steam pipe 20, and steam obtained from the boiler 12b is introduced into the steam turbine 14. The steam turbine 14 is configured to generate electricity using the introduced steam.

[0016] A steam discharge channel 22 is connected to the outlet of the steam turbine 14, and the outlet steam from the steam turbine 14 flows through the steam discharge channel 22. The steam discharge channel 22 is connected to the casing outlet that discharges the steam that has been depressurized by driving the impeller inside the steam turbine 14. The temperature and pressure of the steam flowing through the steam discharge channel 22 are lower than the temperature and pressure of the steam (extracted steam) when discharging steam that is in the process of being depressurized.

[0017] The absorber 16 is connected to the boiler 12b through a gas inlet passage 24. Exhaust gas discharged from the boiler 12b is introduced into the absorber 16. That is, the exhaust gas flowing into the absorber 16 is exhaust gas that has been heated in the boiler 12b and has a temperature lower than the temperature at the combustion furnace 12a. Equipment for purifying the exhaust gas may be provided in the gas inlet passage 24. This purification process may include dust removal, denitrification, desulfurization, etc. The absorber 16 and the regenerator 18 are connected to each other through a supply passage 27 and a return passage 28, so that the processed liquid circulates between the absorber 16 and the regenerator 18. For efficient use of heat, a heat exchanger may be provided between the supply passage 27 and the return passage 28 to perform heat exchange.

[0018] In the absorber 16, the exhaust gas (the gas to be treated) comes into contact with the treatment liquid, and the acidic compounds contained in the gas to be treated are absorbed by the treatment liquid. The treated gas, which is the gas from which the acidic compounds have been removed, is discharged to the outside through the gas discharge passage 30. The treated gas contains, for example, nitrogen and carbon dioxide.

[0019] The processed liquid (rich liquid) that has absorbed the acidic compounds in the absorber 16 is introduced into the regenerator 18 through the feed channel 27. The regenerator 18 is equipped with a steam condenser 32 connected to the steam discharge channel 22. The regenerator 18 is configured to heat the processed liquid inside the regenerator 18 with the outlet steam introduced into the steam condenser 32. When the processed liquid is heated by the outlet steam, it releases the acidic compounds. This separates the acidic compounds from the gas being treated.

[0020] The treatment liquid (lean liquid) after the acidic compounds have been separated is returned to the absorber 16 through the return channel 28. This allows the treatment liquid to be used again to absorb acidic compounds from the gas being treated.

[0021] In the steam condenser 32 located in the regenerator 18, the outlet steam condenses into condensed water by heating the processing liquid.

[0022] A storage tank 34 is provided in the steam discharge channel 22 downstream of the steam condenser 32. That is, the steam discharge channel 22 includes an upstream section 22a that connects the steam turbine 14 and the steam condenser 32 to each other, and a downstream section 22b that connects the steam condenser 32 and the storage tank 34 to each other. Steam flows through the upstream section 22a, while condensed water flows through the downstream section 22b. The condensed water produced in the steam condenser 32 is stored in the storage tank 34 through the downstream section 22b.

[0023] The steam discharge channel 22 also includes a connecting channel 22c that allows condensed water, generated while flowing from the steam turbine 14 to the steam condenser 32, to flow into the storage tank 34. The connecting channel 22c branches off from the upstream side 22a of the steam discharge channel 22 and is connected to the storage tank 34. The storage tank 34 is connected to a discharge channel 36 that discharges the condensed water to the outside. Note that the connecting channel 22c is optional.

[0024] The treatment solution (absorbent) used 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. Alternatively, the treatment solution may be an aqueous solution of the amine compound without an organic solvent. Furthermore, the treatment solution may consist of an amine compound, an organic solvent, an ionic liquid or a mixture thereof, or an aqueous solution. In other words, the treatment solution may contain water and non-aqueous components.

[0025] Here, a gas separation method for separating acidic compounds from a gas to be treated using the gas separation apparatus 10 configured as described above will be explained.

[0026] First, in the combustion furnace 12a of the combustion device 12, high-temperature exhaust gas is generated by the combustion of fuel. This exhaust gas flows into the boiler 12b, heats water, and generates steam. The exhaust gas (gas to be treated) that has heated the water is discharged from the boiler 12b, i.e., the combustion device 12, and introduced into the absorber 16. In the absorber 16, the exhaust gas comes into contact with the treatment liquid, and the acidic compounds contained in the exhaust gas are absorbed into the treatment liquid. As a result, the treated gas, after the acidic compounds have been separated from the gas to be treated, is discharged to the outside. The treatment liquid (rich liquid) that has absorbed the acidic compounds is introduced into the regenerator 18 through the feed channel 27.

[0027] Meanwhile, the steam obtained from the boiler 12b of the combustion device 12 is introduced into the steam turbine 14, where electricity is generated. The steam used for power generation in the steam turbine 14 flows from the outlet of the steam turbine 14 into the steam discharge channel 22, and this outlet steam is introduced into the steam condenser 32 through the steam discharge channel 22.

[0028] In the steam condenser 32 of the regenerator 18, the processing liquid (rich liquid) is heated by the outlet steam. As a result, the outlet steam condenses, and at the same time, acidic compounds are separated from the processing liquid. The processing liquid (lean liquid) from which the acidic compounds have been separated is returned to the absorber 16 through the return channel 28.

[0029] As described above, in the gas separation apparatus 10 according to this embodiment, the outlet steam of the steam turbine 14 is introduced into the steam condenser 32 located in the regenerator 18, and the processing liquid is heated by this outlet steam in the regenerator 18. As a result, the processing liquid is heated while the outlet steam condenses, and acidic compounds are separated from the processing liquid. In this way, since the outlet steam of the steam turbine 14 is used to regenerate the processing liquid in the regenerator 18, it is possible to avoid a situation in which the power generation performance of the steam turbine 14 is reduced. Moreover, since the outlet steam condenses in the regenerator 18, the processing liquid can be regenerated by utilizing the latent heat of condensation of the outlet steam. In other words, since the latent heat of condensation that was conventionally wasted in condensers and the like can be utilized, energy saving can be achieved.

[0030] (Second Embodiment) As shown in Figure 2, in the second embodiment, a pressure reducer 40 is added. Here, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted.

[0031] The pressure reducer 40 is used to reduce the pressure in the steam discharge channel 22 through which steam flowing out of the steam turbine 14 flows, and has a vacuum pump 40a connected to the storage tank 34. When the vacuum pump 40a is activated, the pressure in the steam discharge channel 22 is reduced. As a result, the pressure and temperature of the steam at the outlet of the steam turbine 14 decrease, and the condensation temperature of the steam introduced into the steam condenser 32 decreases.

[0032] In this case, the condensation temperature of water vapor in the steam condenser 32 can be lowered, allowing the regeneration temperature of the treatment liquid to be set to a lower temperature. Therefore, a treatment liquid that can release acidic compounds at a lower regeneration temperature will be used as the treatment liquid.

[0033] The treatment solution may be, for example, an alkaline absorbent containing water, an amine compound, and an organic solvent. In this case, the treatment solution may contain 30 wt% of the amine compound, 60 wt% of the organic solvent, and 10 wt% of the water. If the treatment solution is one that undergoes phase separation by absorption of an acidic compound, it becomes possible to set regeneration conditions at lower temperatures.

[0034] Examples of amine compounds include 2-aminoethanol (MEA: solubility parameter = 14.3 (cal / cm³)). ３ ) １／２ ), 2-(2-aminoethoxy)ethanol (AEE: solubility parameter = 12.7 (cal / cm³) ３ ) １／２Primary amines such as (etc.), secondary amines such as 2-(methylamino)ethanol (MAE), 2-(ethylamino)ethanol (EAE), 2-(butylamino)ethanol (BAE), etc., and tertiary amines such as triethanolamine (TEA), N-methyldiethanolamine (MDEA), tetramethylethylenediamine (TEMED), pentamethyldiethylenetriamine (PMDETA), hexamethyltriethylenetetramine, bis(2-dimethylaminoethyl) ether, etc. are included.

[0035] As the 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. are included, and a plurality of these may be mixed and used.

[0036] When the solubility parameters of the amine compound and the organic solvent are within a predetermined range, the treatment liquid is phase-separated into a phase with a high content rate of the acidic compound and a phase with a low content rate of the acidic compound by absorption of the acidic compound. Here, the solubility parameter is represented by the following formula (1).

[0037]

[0038] ΔH is the molar heat of vaporization, R is the gas constant, T is the absolute temperature, and V is the molar volume.

[0039]

[0040] As shown in Table 1, in the 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 / cm ３ ) １／２ or more and 4.2 (cal / cm ３ ) １／２By 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.

[0041] It is desirable to set the absorption conditions in the absorber 16 to a region where the processing liquid separates into two phases and a large amount of carbon dioxide dissolves, and to set the regeneration conditions in the regenerator 18 to a region where the processing 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 processing 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 this case, it is also possible to set the absorption temperature to, for example, 40°C and the regeneration temperature to, for example, 90°C or lower.

[0042] In the second embodiment, the pressure reducer 40 can reduce the pressure in the steam discharge channel 22. As a result, the pressure and temperature of the steam at the outlet of the steam turbine 14 decrease, and the condensation temperature of the steam introduced into the steam condenser 32 decreases. That is, the heat drop in the steam turbine 14 can be increased, thereby improving the power generation performance of the steam turbine 14. Furthermore, because the condensation temperature of the steam in the steam condenser 32 decreases, if a lower temperature condition can be achieved when regenerating the treated liquid in the regenerator 18, the latent heat of steam condensation can be effectively utilized.

[0043] Furthermore, if the outlet steam (water vapor) is reduced to a pressure below atmospheric pressure, for example, the outlet steam can be condensed at a temperature below 100°C. In other words, if low regeneration temperature conditions can be achieved for the processed liquid, it becomes possible to effectively utilize the latent heat of condensation of the outlet steam, and the amount of power generated can also be increased. To put it another way, it is possible to avoid a situation where the amount of power generated in the steam turbine 14 must be sacrificed in order to secure a high regeneration temperature in the regenerator 18.

[0044] The vacuum pump 40a of the pressure reducer 40 is connected to the storage tank 34, but is not limited to this. For example, the vacuum pump 40a may be connected to the upstream side 22a of the steam discharge passage 22, or it may be connected to the connecting passage 22c.

[0045] Furthermore, in the second embodiment, as shown in Figure 3, an introduction means 42 for introducing a separation-accelerating gas into the regenerator 18 may be provided. The separation-accelerating gas is a gas used in the regenerator 18 to promote the separation of acidic compounds from the processing liquid. The introduction means 42 includes an introduction passage 42a connected to the regenerator 18, and the separation-accelerating gas is introduced into the regenerator 18 through this introduction passage 42a. By using the separation-accelerating gas, it becomes possible to set a lower temperature as the regeneration temperature in the regenerator 18.

[0046] The separation-accelerating gas is a gas that is almost insoluble in the processing liquid. In other words, the separation-accelerating gas is hardly absorbed by the processing liquid. Therefore, by introducing the separation-accelerating gas into the regenerator 18, the partial pressure of acidic compounds (such as carbon dioxide) in the regenerator 18 can be lowered, thereby promoting the separation of acidic compounds from the processing liquid. Examples of separation-accelerating gases include hydrocarbon gases such as hydrogen gas, oxygen gas, and methane gas. 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 acidic compounds. In other words, the separation-accelerating gas is a gas that lowers the partial pressure of acidic compounds in the regenerator 18.

[0047] When the separation-accelerating gas is described as "almost insoluble in the processing solution," it may also 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. 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 at mol / 100g, is 9.5 × 10⁻⁶. －５ The solubility 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.

[0048] When a separation-accelerating gas is used, the regeneration temperature of the processed liquid in the regenerator 18 can be lowered, making the regeneration of the processed liquid using the outlet steam of the steam turbine 14 more effective. Therefore, energy savings can be achieved throughout the entire process from the combustion device 12 to the regenerator 18.

[0049] Furthermore, the introduction means 42 for introducing the separation-promoting gas into the regenerator 18 may be added to the configuration of the first embodiment, which does not have a pressure reducer 40, as shown in Figure 4.

[0050] 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.

[0051] (Third Embodiment) As shown in Figure 5, the gas separation device 10 of the third embodiment is used in connection with a utilization device 44 that utilizes the acidic compounds separated in the regenerator 18. Here, the same reference numerals are used for the same components as in the first or second embodiment, and their detailed descriptions are omitted.

[0052] In the third embodiment, a separation-accelerating gas is introduced into the regenerator 18. Hydrogen gas is used as the separation-accelerating gas. The separation-accelerating gas may also contain water vapor.

[0053] Water vapor or moisture generated in the regenerator 18 is discharged through the water discharge channel 45. Specifically, as shown in Figure 6, the regenerator 18 is connected to a supply channel 48 for discharging gas (emission gas) containing carbon dioxide, which is an acidic compound separated from the processing liquid in the regenerator 15. The supply channel 48 is equipped with a condenser 49 for condensing moisture contained in the emission gas and a separator 50 for separating moisture from the emission gas that has passed through the condenser 49. In the condenser 49, moisture contained in the emission gas condenses, and the water discharge channel 45 is connected to the separator 50 so that this condensed moisture (which may contain some water vapor) can be discharged. The supply channel 48 also supplies the emission gas from which moisture has been removed in the separator 50 to the utilization device 44.

[0054] The steam turbine 14 is connected to an extraction passage 46 for discharging steam that is being depressurized, but this extraction passage 46 is optional.

[0055] The utilization device 44 is connected to the regenerator 18 through a supply line 48. The gas containing carbon dioxide, an acidic compound separated from the processing liquid in the regenerator 18 (emission gas), from which water has been removed in the separator 50, is introduced into the utilization device 44 through the supply line 48. The utilization device 44 may be, for example, a device that synthesizes methane or methanol by reacting hydrogen and carbon dioxide. That is, the carbon dioxide separated from the processing liquid in the regenerator 18 and the hydrogen contained in the separation-promoting gas introduced into the regenerator 18 through the introduction line 42a are introduced into the utilization device 44, and methane or methanol is synthesized in the utilization device 44 using these. Note that the utilization device 44 is not limited to a device that performs methanation, but can be any device that utilizes acidic compounds such as carbon dioxide for some purpose.

[0056] The introduction means 42 includes an introduction-side adjustment mechanism V1 located in the introduction passage 42a. The introduction-side adjustment mechanism V1 includes a valve and the like, and is configured to adjust the flow rate of the separation-promoting gas introduced into the regenerator 18. The gas separation device 10 includes a control device 51 which includes a control unit that controls the introduction-side adjustment mechanism V1 (introduction means 42) so that the ratio of the acidic compound and the separation-promoting gas supplied to the utilization device 44 is a predetermined ratio.

[0057] If methanation is to be performed in the utilization device 44, the control device 51 controls the introduction-side adjustment mechanism V1 so that the H2 / CO2 ratio is 4, that is, the ratio of moles of hydrogen to moles of carbon dioxide is 4.

[0058] An outlet-side adjustment mechanism V4 is located in the water discharge channel 45. The outlet-side adjustment mechanism V4 includes a valve and is configured to adjust the flow rate of water vapor or moisture discharged from the regenerator 18. The control device 51 also includes a control unit that controls the outlet-side adjustment mechanism V4 so that the moisture content of the processed liquid in the gas separation device 10 approaches a predetermined moisture content.

[0059] The control of adjustment mechanisms V1 and V4 by the control device 51 is performed based on information input to the control device 51 (and information obtained from this information). The information input to the control device 51 includes the flow rate Qi and moisture content Hi of the gas to be treated introduced into the absorber 16 through the gas inlet passage 24, the flow rate Qao and moisture content Hao of the treated gas discharged from the absorber 16 through the gas discharge passage 30, and the flow rate Qro and moisture content Hro of the gas (emissioned gas) led out from the regenerator 18 through the supply passage 48.

[0060] QV4 is the flow rate of water vapor or moisture discharged through the water discharge channel 45, which is equipped with the outlet-side adjustment mechanism V4. Qh is the flow rate of moisture introduced by the separation-promoting gas introduced into the regenerator 18 through the inlet channel 42a, which is equipped with the inlet-side adjustment mechanism V1. Temperature sensors and pressure sensors (not shown) may be provided in the gas inlet channel 24, gas discharge channel 30, supply channel 48, water discharge channel 45, and inlet channel 42a, respectively. In this case, in order to reduce the influence of temperature and pressure on the gas flow rate, the flow rates Qi, Qao, Qro, QV4, and Qh may be corrected values ​​based on the measurement results of the temperature sensor and pressure sensor. Furthermore, if water such as wash water is supplied to the absorber 16, the supply water flow rate Qal may be considered. Furthermore, if water such as wash water is supplied to the regenerator 18, the supply water flow rate Qrl may be considered.

[0061] The amount of water W accumulated in the processing liquid per unit time can be expressed by the following equation (1): W = Qi・Hi - Qao・Hao - Qv4 - Qro・Ho + Qal + Qrl + Qh ... (1)

[0062] When the amount of water W accumulated in the processing liquid per unit time increases, the water content of the processing liquid increases. Conversely, when the amount of water W accumulated in the processing liquid per unit time becomes a negative value, the water content of the processing liquid decreases. Therefore, the flow rate QV4 discharged from the water discharge channel 45 and the flow rate Qh of water introduced through the introduction channel 42a are controlled so that the amount of water W remains within a preset range to stabilize the water content of the processing liquid. In addition, the flow rate Qh of water introduced through the introduction channel 42a (i.e., the flow rate of the separation-promoting gas) is controlled so that the H2 / CO2 ratio becomes a predetermined ratio. In other words, the introduction-side adjustment mechanism V1 is controlled so that the H2 / CO2 ratio becomes a predetermined ratio.

[0063] Information regarding the flow rate Qi of the gas to be treated introduced into the absorber 16 is obtained from a gas flow meter 53 located in the gas inlet passage 24. Information regarding the moisture content Hi of the gas to be treated introduced into the absorber 16 is obtained from a gas detector 54 located in the gas inlet passage 24. The gas detector 54 is a measuring instrument configured to measure the composition of gases containing moisture.

[0064] Information regarding the flow rate Qao of the treated gas discharged from the absorber 16 is obtained from a gas flow meter 55 located in the gas discharge passage 30. Information regarding the moisture content Hao of the treated gas discharged from the absorber 16 is obtained from a gas detector 56 located in the gas discharge passage 30. The gas detector 56 is a measuring instrument configured to measure the composition of gases containing moisture.

[0065] Information regarding the flow rate Qro of the gas (emission gas) discharged from the regenerator 18 is obtained from a gas flow meter 57 located in the supply line 48. Information regarding the moisture content Hro of the gas (emission gas) discharged from the regenerator 18 is obtained from a gas detector 58 located in the supply line 48. The gas detector 58 is a measuring instrument configured to measure the composition of gases containing moisture.

[0066] Here, the control operation of the input-side adjustment mechanism V1 and the output-side adjustment mechanism V4 by the control device 51 will be explained with reference to Figure 7.

[0067] First, as shown in Figure 7, the control device 51 of the gas separation device 10 sets the product conditions for the gas (emission gas) supplied to the utilization device 44 (step ST11). These product conditions include the H2 / CO2 ratio required by the utilization device 44, the flow rate of the emission gas supplied to the utilization device 44, and so on. Next, the control device 51 acquires information indicating the measured flow rate measured by the gas flow meters 53, 55, and 57 from the gas flow meters 53, 55, and 57, and also acquires information indicating the gas composition detected by the gas detectors 54, 56, and 58 from the gas detectors 54, 56, and 58 (step ST12).

[0068] Furthermore, the control device 51 acquires information indicating the detected values ​​of the temperature sensors and pressure sensors installed in the gas inlet passage 24, gas outlet passage 30, supply passage 48, water outlet passage 45, and introduction passage 42a, and performs temperature and pressure correction for each gas flow rate (step ST13). This corrected gas flow rate is taken as the measured value. Alternatively, this temperature and pressure correction step may be omitted, and the gas flow rate obtained from the gas flow meters 53, 55, and 57 may be taken as the measured value. In this case, the temperature sensors and pressure sensors may be omitted. Also in step ST13, the control device 51 determines the measured value of the water content of the processed liquid based on the information obtained from the gas detectors 54, 56, and 58.

[0069] In step ST13, the measured flow rate and moisture content of the gas to be treated introduced into the absorber 16 are used as Qi and Hi in equation (1). Similarly, the flow rate and moisture content of the treated gas discharged from the absorber 16 are used as Qao and Hao, and the flow rate and moisture content of the emitted gas led out from the regenerator 18 are used as Qro and Ho in equation (1).

[0070] Next, the control device 51 calculates an actual value for the H2 / CO2 ratio of the emitted gas flowing through the supply passage 48 based on the actual value of the derived gas flow rate, and compares this actual value for the H2 / CO2 ratio of the emitted gas with the H2 / CO2 ratio (set value) set in step ST11 (step ST14). If the actual value falls within the set range relative to the set value (YES in step ST14), the process proceeds to step ST15.

[0071] In step ST15, the control device 51 uses equation (1) to determine whether the amount of water W accumulated in the processing liquid per unit time is within the set range. If the amount of water W is within the set range, the inlet-side adjustment mechanism V1 and the outlet-side adjustment mechanism V4 are maintained in their current state.

[0072] On the other hand, if the measured value of the H2 / CO2 ratio of the emitted gas flow rate falls outside the predetermined range relative to the set value (NO in step ST14), the process proceeds to step ST16. In step ST16, it is determined whether the measured value of the H2 / CO2 ratio is higher than the set value. If the measured value is higher than the set value, the control device 51 controls the inlet-side adjustment mechanism V1 so that the flow rate of the separation-promoting gas supplied to the regenerator 18 through the inlet passage 42a is reduced (step ST17). On the other hand, if the measured value is lower than the set value, the control device 51 controls the inlet-side adjustment mechanism V1 so that the flow rate of the separation-promoting gas supplied to the regenerator 18 through the inlet passage 42a is increased (step ST18). As a result, the H2 / CO2 ratio of the emitted gas flow rate is adjusted to approach the set product conditions.

[0073] In step ST15, if it is determined that the amount of water W accumulated in the processing liquid per unit time is outside the set range (NO in step ST15), the process proceeds to step ST19. In step ST19, it is determined whether the amount of water W accumulated in the processing liquid per unit time is higher than the set range. If the amount of water W is higher than the set range, the control device 51 controls the outlet side adjustment mechanism V4 so that the flow rate QV4 of water vapor or water discharged from the regenerator 18 through the water discharge passage 45 increases (step ST20). As a result, the flow rate QV4 of water vapor or water discharged to the outside increases, and the amount of water contained in the processing liquid can be reduced. This stabilizes the water content of the processing liquid. At this time, the water content of the processing liquid may be adjusted to a range of, for example, 5 w% to 30 w%, preferably 5 w% to 20 w%, and more preferably 10 w% to 20 w%. The content of the amine compound may also be 20 w% to 40 w%.

[0074] On the other hand, if the moisture content W is lower than the set range, the control device 51 controls the outlet side adjustment mechanism V4 so that the flow rate QV4 of steam or moisture discharged from the regenerator 18 through the water discharge passage 45 is reduced (step ST21). As a result, the flow rate QV4 of steam or moisture discharged to the outside is reduced, which increases the amount of moisture contained in the processed liquid. This stabilizes the moisture content of the processed liquid.

[0075] Therefore, according to this embodiment, the flow rate Qh of the separation-promoting gas is adjusted by the introduction-side adjustment mechanism V1 and the control device 51 so that the ratio of the acidic compound to the separation-promoting gas becomes the ratio required in the utilization device 44. This makes it easier for gas of the required composition to be introduced into the utilization device 44. In addition, the flow rate QV4 of water vapor or water discharged through the water discharge channel 45 is adjusted by the outlet-side adjustment mechanism V4 and the control device 51 so that the amount of water W accumulated in the processing liquid per unit time falls within the set range. This stabilizes the water content of the processing liquid, thereby stabilizing the separation capacity of the acidic compound. Therefore, it contributes to stable operation.

[0076] 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.

[0077] (Fourth Embodiment) The fourth embodiment differs from the third embodiment in that, in addition to adjusting the flow rate Qh of the separation-promoting gas and the flow rate QV4 of the steam or moisture discharged from the regenerator 18, the flow rate of the outlet steam is also controlled. Here, the same reference numerals are used for components that are the same as in the first to third embodiments, and their detailed descriptions are omitted.

[0078] As shown in Figure 8, the gas separation device 10 of the fourth embodiment further includes a steam volume adjustment mechanism V3 and a gas flow rate adjustment mechanism V2.

[0079] The steam flow rate adjustment mechanism V3 is located in the steam discharge passage 22, in the upstream section 22a where the steam turbine 14 and the steam condenser 32 are connected to each other. The steam flow rate adjustment mechanism V3 includes valves and the like, and adjusts the flow rate of the outlet steam. The gas flow rate adjustment mechanism V2 includes valves and the like, located in the gas inlet passage 24, and adjusts the flow rate of the gas to be treated supplied to the absorber 16.

[0080] A gas flow meter 60 for measuring the flow rate of the outlet steam is located in the steam discharge channel 22. A temperature sensor and a pressure sensor (not shown) may also be provided in the steam discharge channel 22. In this case, the flow rate measured by the gas flow meter is corrected based on the temperature and pressure detected by the temperature and pressure sensors. Note that the temperature and pressure sensors are optional.

[0081] In the gas separation method using the gas separation device 10 according to the fourth embodiment, as shown in Figure 9, in step ST12, information on gas flow rate and composition is obtained from gas flow meters 53, 55, 57 and gas detectors 54, 56, 58, and further information on outlet steam flow rate is obtained from gas flow meter 60 located in the steam discharge channel 22. In step ST13, the measured values ​​of each gas flow rate and moisture content are calculated, similar to the third embodiment, and further, the measured value of the outlet steam flow rate introduced into the steam condenser 32 is determined.

[0082] Based on the flow rate of the radiated gas flowing through the supply passage 48 obtained in step ST13, the control device 51 controls the gas flow rate adjustment mechanism V2 (step ST31). That is, the flow rate of the gas to be treated received from the combustion device 12 is adjusted according to the flow rate of the radiated gas supplied to the utilization device 44. In this case, the gas flow rate adjustment mechanism V2 is controlled such that the flow rate of the gas to be treated passing through the gas flow rate adjustment mechanism V2 increases as the amount requested from the utilization device 44 increases, and decreases as the amount requested from the utilization device 44 decreases.

[0083] Furthermore, the flow rate of the outlet steam by the steam flow rate adjustment mechanism V3 is adjusted according to the flow rate of the gas to be treated that the absorber 16 receives (step ST32). That is, when the flow rate of the gas to be treated that the absorber 16 receives increases, and the gas flow rate measured by the gas flow meter 53 increases, the flow rate of the processed liquid sent to the regenerator 18 also increases. For this reason, in order to increase the amount of heating of the processed liquid, the steam flow rate adjustment mechanism V3 is controlled by the control device 51 so that the flow rate of the outlet steam flowing through the steam discharge channel 22 increases. On the other hand, when the flow rate of the gas to be treated that the absorber 16 receives decreases, and the gas flow rate measured by the gas flow meter 53 decreases, the flow rate of the processed liquid sent to the regenerator 18 decreases. For this reason, in order to reduce the amount of heating of the processed liquid, the steam flow rate adjustment mechanism V3 is controlled by the control device 51 so that the flow rate of the outlet steam flowing through the steam discharge channel 22 decreases. With the outlet steam flow rate adjusted in this manner, in step ST14, the measured value of the H2 / CO2 ratio of the emitted gas flowing through the supply passage 48 is compared with the set value of the H2 / CO2 ratio, and in step ST15, it is determined whether the amount of water W accumulated in the processing liquid per unit time falls within the set range.

[0084] Therefore, according to this embodiment, the flow rate of the outlet steam is adjusted by the steam flow rate adjustment mechanism V3 according to the flow rate of the emitted gas supplied to the utilization device 44. As a result, the regeneration capacity of the processed liquid in the regenerator 18 is adjusted, making it possible to operate the utilization device 44 according to the amount of gas required.

[0085] 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.

[0086] (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 the spirit of the invention.

[0087] The specific embodiments described above mainly include inventions having the following configurations.

[0088] (1) The gas separation apparatus according to the above embodiment comprises a combustion apparatus having a boiler, a steam turbine into which steam obtained from the boiler is introduced, an absorber configured to bring a gas to be treated, which is discharged from the combustion apparatus and contains an acidic compound that produces acid when dissolved in water, into contact with a processing liquid and to allow the acidic compound contained in the gas to be treated to be absorbed into the processing liquid, a steam condenser into which the outlet steam from the steam turbine is introduced, and a regenerator into which the steam condenser is located and the processing liquid that has absorbed the acidic compound is introduced. The regenerator is configured to heat the processing liquid by the heat of the outlet steam as the outlet steam flowing through the steam condenser condenses, and the acidic compound is separated from the processing liquid heated in the regenerator.

[0089] In the aforementioned gas separation apparatus, the outlet steam from the steam turbine is introduced into a steam condenser located in the regenerator, where the treatment liquid is heated by this outlet steam. As a result, the outlet steam condenses while the treatment liquid is heated, separating acidic compounds from the treatment liquid. In this way, since the outlet steam from the steam turbine is used to regenerate the treatment liquid in the regenerator, a decrease in the power generation performance of the steam turbine can be avoided. Moreover, since the outlet steam condenses in the regenerator, the latent heat of condensation of the outlet steam can be used to regenerate the treatment liquid. In other words, since the latent heat of condensation that was conventionally wasted in condensers and the like can be used, energy savings can be achieved.

[0090] (2) The gas separation device may further include a pressure reducer configured to reduce the pressure in the steam discharge channel through which the outlet steam flowing out of the steam turbine flows.

[0091] In this configuration, the pressure in the steam discharge channel can be reduced by the pressure reducer. Consequently, the pressure and temperature of the steam outlet from the steam turbine can be reduced, and the condensation temperature of the outlet steam introduced into the steam condenser can be reduced. In other words, the heat drop in the steam turbine can be increased, thereby improving the power generation performance of the steam turbine. Furthermore, because the condensation temperature of the steam in the steam condenser is reduced, if lower temperature conditions can be achieved when regenerating the treated liquid in the regenerator, the latent heat of condensation of the outlet steam can be effectively utilized.

[0092] (3) The gas separation apparatus may further include an introduction means configured to introduce a separation-promoting gas into the regenerator to promote the separation of the acidic compound from the processing liquid.

[0093] In this embodiment, the regeneration temperature of the processing liquid in the regenerator can be lowered, making the regeneration of the processing liquid using steam from the steam turbine outlet more effective. Therefore, energy savings can be achieved throughout the entire process, from the combustion unit to the regenerator.

[0094] (4) The gas separation device may be connected to and used in a utilization device that utilizes the acidic compound separated in the regenerator. In this case, the gas separation device may be equipped with a control device configured to control the introduction means so that the ratio of the acidic compound contained in the gas introduced into the utilization device to the separation-promoting gas becomes the ratio required by the utilization device.

[0095] In this embodiment, the control device controls the introduction means so that the ratio of the acidic compound to the separation-promoting gas becomes the ratio required by the utilization device. This makes it easier for the required gas to be introduced into the utilization device. Therefore, it contributes to stable operation.

[0096] (5) The gas separation device may include a gas flow meter configured to measure the flow rate of the gas to be treated at the inlet of the absorber, a gas detector configured to detect the composition of the gas to be treated at the inlet of the absorber, a gas flow meter configured to measure the flow rate of the treated gas at the top of the absorber, a gas detector configured to detect the composition of the treated gas at the top of the absorber, a gas flow meter configured to measure the flow rate of the gas at the top of the regenerator, a gas detector configured to detect the composition of the gas at the top of the regenerator, and an adjustment mechanism configured to adjust the flow rate of moisture discharged from the regenerator.

[0097] In this embodiment, the water flow rate discharged from the regenerator is adjusted according to the measurement results from each gas flow meter and the detection results from each gas detector. This stabilizes the water content of the processed liquid, thereby enabling stable operation of the gas separation device.

[0098] (6) The control device may be configured to control the adjustment mechanism so that the water content of the processing liquid falls within a set range. In this embodiment, the water content of the processing liquid is stabilized, and the separation ability of acidic compounds can be stabilized.

[0099] (7) The gas separation device may include a steam flow rate adjustment mechanism configured to adjust the flow rate of the outlet steam introduced into the steam condenser.

[0100] In this embodiment, the flow rate of the outlet steam introduced into the steam condenser is adjustable. For example, the steam flow rate adjustment mechanism can adjust the flow rate of the outlet steam according to the gas flow rate supplied to the utilization device. In this case, as the flow rate of the outlet steam is adjusted, the regeneration capacity of the processed liquid is adjusted, making it possible to operate the device according to the amount of gas required by the utilization device.

[0101] (8) The control device may be configured to control the steam amount adjustment mechanism according to the measurement result of the gas flow meter that measures the gas flow rate at the top of the regenerator or the measurement result of the gas flow meter that measures the flow rate of the gas to be treated at the inlet of the absorber. In this embodiment, a separation capacity of acidic compounds in an amount corresponding to the amount of gas required from the user device can be obtained.

[0102] (9) The gas separation method according to the above embodiment involves: discharging a gas to be treated containing an acidic compound that produces acid when dissolved in water from a combustion device; introducing the gas to be treated discharged from the combustion device into an absorber and bringing it into contact with a processing liquid to allow the acidic compound contained in the gas to be treated to be absorbed into the processing liquid; introducing the steam obtained from the boiler of the combustion device into a steam turbine to generate electricity; introducing the outlet steam from the steam turbine into a steam condenser; and in a regenerator where the steam condenser is located, heating the processing liquid that has absorbed the acidic compound with the outlet steam, and separating the acidic compound from the processing liquid while condensing the outlet steam.

[0103] As explained above, it is possible to regenerate the treated liquid while suppressing the reduction in power generation capacity by the turbine.

[0104] This application is based on Japanese Patent Application No. 2024-225145, filed with the Japan Patent Office on December 20, 2024, the contents of which are incorporated herein by reference.

[0105] To illustrate the present invention, the embodiments have been adequately and fully described above with reference to the drawings. However, those skilled in the art should recognize that it is easy to modify and / or improve upon the embodiments described above. Therefore, unless such modifications or improvements implemented by those skilled in the art fall outside the scope of the claims, such modifications or improvements shall be considered to be included within the scope of the claims.

Claims

1. A gas separation apparatus comprising: a combustion device having a boiler; a steam turbine into which steam obtained from the boiler is introduced; an absorber configured to bring a gas to be treated, which is discharged from the combustion device and contains an acidic compound that produces acid when dissolved in water, into contact with a processing liquid, and to absorb the acidic compound contained in the gas to be treated into the processing liquid; a steam condenser into which the outlet steam from the steam turbine is introduced; and a regenerator into which the processing liquid, which has absorbed the acidic compound, is introduced, wherein the regenerator is configured to heat the processing liquid by the heat of the outlet steam as the outlet steam flowing through the steam condenser condenses, and the acidic compound is separated from the processing liquid heated in the regenerator.

2. The gas separation apparatus according to claim 1, further comprising a pressure reducer configured to reduce the pressure in the steam discharge channel through which the outlet steam flowing out of the steam turbine flows.

3. The gas separation apparatus according to claim 1 or 2, further comprising an introduction means configured to introduce a separation-promoting gas that promotes the separation of the acidic compound from the processing liquid into the regenerator.

4. The gas separation apparatus according to claim 3, wherein the gas separation apparatus is connected to a utilization apparatus that utilizes the acidic compound separated in the regenerator, and includes a control device configured to control the introduction means so that the ratio of the acidic compound contained in the gas introduced into the utilization apparatus to the separation-promoting gas becomes the ratio required by the utilization apparatus.

5. The gas separation apparatus according to claim 4, comprising: a gas flow meter configured to measure the flow rate of the gas to be treated at the inlet of the absorber; a gas detector configured to detect the composition of the gas to be treated at the inlet of the absorber; a gas flow meter configured to measure the flow rate of the treated gas at the top of the absorber; a gas detector configured to detect the composition of the treated gas at the top of the absorber; a gas flow meter configured to measure the flow rate of the gas at the top of the regenerator; a gas detector configured to detect the composition of the gas at the top of the regenerator; and an adjustment mechanism configured to adjust the flow rate of moisture discharged from the regenerator.

6. The gas separation apparatus according to claim 5, wherein the control device is configured to control the adjustment mechanism so that the water content of the processing liquid falls within a set range.

7. The gas separation apparatus according to claim 5, further comprising a steam flow rate adjustment mechanism configured to adjust the flow rate of the outlet steam introduced into the steam condenser.

8. The gas separation apparatus according to claim 7, wherein the control device is configured to control the steam amount adjustment mechanism according to the measurement result of the gas flow meter used to measure the gas flow rate at the top of the regenerator or the measurement result of the gas flow meter used to measure the flow rate of the gas to be treated at the inlet of the absorber.

9. A gas separation method comprising: discharging a gas to be treated containing an acidic compound that produces acid upon dissolution in water from a combustion device; introducing the gas to be treated discharged from the combustion device into an absorber and bringing it into contact with a treatment liquid to absorb the acidic compound contained in the gas to be treated into the treatment liquid; introducing steam obtained from the boiler of the combustion device into a steam turbine to generate electricity; introducing the outlet steam of the steam turbine into a steam condenser; and in a regenerator where the steam condenser is located, heating the treatment liquid that has absorbed the acidic compound with the outlet steam, and separating the acidic compound from the treatment liquid while condensing the outlet steam.

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