Carbon dioxide gas separation device and carbon dioxide gas separation method

Abstract

[Problem] To provide a carbon dioxide gas separation device and a carbon dioxide gas separation method which make it possible to efficiently separate water from an exhaust gas which contains carbon dioxide gas. [Solution] A carbon dioxide gas separation device 1 has: an oxygen supply unit 10A; a combustion unit 12 comprising a combustion furnace 12A which is supplied with oxygen from the oxygen supply unit 10A and in which said oxygen is combusted together with supplied fuel, and a dehumidifier 40 which separates water from a combustion gas which has been generated in the combustion furnace 12A and which contains the water and carbon dioxide gas; and a water separation unit 15 into which the exhaust gas discharged from the combustion unit 12 is introduced and which separates remaining water from the exhaust gas. The water separation unit 15 is provided between the oxygen supply unit and the combustion furnace and comprises: an oxygen introduction port for introducing dry oxygen which is supplied from the oxygen supply unit 10A, an oxygen discharge port for discharging oxygen, which contains water, to the combustion unit, an exhaust gas introduction port for introducing the exhaust gas which has been discharged from the combustion unit and contains water and carbon dioxide gas; and an exhaust gas discharge port for discharging dry exhaust gas from which the water has been removed.

Description

Carbon dioxide separation device and carbon dioxide separation method

[0001] The present invention relates to a carbon dioxide gas separation device that can be installed in, for example, a factory, a power plant, a hydrogen gas station, etc., and that separates and recovers carbon dioxide gas from exhaust gas, and a carbon dioxide gas separation method that separates carbon dioxide gas from exhaust gas.

[0002] In recent years, in order to realize a carbon-free society, there has been a demand for technology to separate and capture carbon dioxide from exhaust gas after combustion.One known technology for separating and capturing carbon dioxide from exhaust gas after combustion is the oxyfuel combustion method, which combines oxyfuel combustion with a gas separation device and is expected to be highly efficient.

[0003] Various methods of oxyfuel combustion are known, and for example, Patent Document 1 discloses an exhaust gas treatment system that includes a compressor that makes exhaust gas water-soluble, a cooler that cools the compressed exhaust gas, condenses the moisture, and extracts drainage containing dissolved impurities, and a dryer. Also, Patent Document 2 discloses an exhaust gas treatment system that includes a heat recovery unit that recovers heat from the exhaust gas and a cooling and dehumidifying device that removes moisture from the exhaust gas.

[0004] Patent No. 5780244 Patent No. 5432098

[0005] In the oxyfuel combustion method, carbon dioxide gas is separated and recovered by passing the exhaust gas through a gas separation device equipped with an adsorbent. However, gas separation devices using adsorbents have the problem that their ability to adsorb carbon dioxide gas gradually decreases because they adsorb moisture. This is because their performance decreases if exhaust gas containing moisture is continuously supplied. To avoid this problem, it is possible to install a dehumidifier in the upstream stage of the gas separation device to remove moisture from the exhaust gas, but this requires a large amount of power and is inefficient.

[0006] The present invention has been made in light of the above-mentioned problems, and aims to provide a carbon dioxide separation device and a carbon dioxide separation method that can efficiently separate moisture from exhaust gas containing carbon dioxide.

[0007] In order to achieve the above-mentioned object, the carbon dioxide separation apparatus of the present invention comprises: a first gas supply unit that supplies a dry first gas; a second gas supply unit that supplies a second gas; a reaction furnace to which the dry first gas from the first gas supply unit is supplied and which undergoes a reaction together with the second gas; and a reaction unit including a dehumidifier that separates moisture from a product gas containing moisture and carbon dioxide gas produced in the reaction furnace; and a moisture separation unit to which dehumidified product gas discharged from the dehumidifier in the reaction unit is introduced and which separates moisture remaining in the dehumidified product gas, the moisture separation unit being provided between the first gas supply unit and the reaction furnace and comprising: a first gas inlet that introduces the dry first gas supplied from the first gas supply unit; a first gas outlet that discharges the moisture-containing first gas into the reaction furnace; a product gas inlet that introduces the dehumidified product gas containing at least moisture and carbon dioxide gas that is discharged from the reaction unit; and a product gas outlet that discharges the dry product gas from which moisture has been removed.

[0008] In the carbon dioxide separation apparatus having the above configuration, the dehumidified product gas discharged from the reaction section is introduced into the moisture separation section through the product gas inlet, where the moisture is separated and recovered, and the highly concentrated product gas (carbon dioxide gas) is discharged through the product gas outlet. In this moisture separation section, a dry state is maintained by the dry first gas supplied from the first gas supply section through the first gas inlet, so moisture separation performance does not deteriorate. In other words, the moisture separation section can efficiently maintain a dry state with a simple structure, eliminating the need for a dedicated dehumidifying device and requiring no large power, thereby enabling the overall apparatus to be made smaller.

[0009] In addition, in order to achieve the above-mentioned object, the carbon dioxide separation method of the present invention is characterized by having a reaction step in which a dry first gas supplied from a first gas supply unit and a second gas supplied from a second gas supply unit are reacted in a reaction unit; a drying step in which the product gas discharged in the reaction step is passed through a moisture separation unit to separate moisture; and a humidification step in which the dry first gas is passed through a moisture separation unit to humidify it.

[0010] According to the carbon dioxide separation method configured as described above, moisture is separated and recovered from the product gas discharged in the reaction step in the drying step, and high-concentration carbon dioxide is discharged. In this drying step, moisture is supplied to the moisture separation section, but moisture is removed from the moisture separation section by the drying first gas supplied from the first gas supply section in the humidification step, so moisture separation performance does not decrease. In other words, in the moisture separation step, moisture is efficiently separated from the dehumidified product gas with a simple structure that simply passes the dehumidified product gas through the moisture separation section, so no large power is required and the entire carbon dioxide separation apparatus can be made smaller.

[0011] According to the present invention, it is possible to obtain a carbon dioxide gas separation device and a carbon dioxide gas separation method that can efficiently separate water from exhaust gas containing carbon dioxide gas.

[0012] FIG. 1 is a schematic diagram showing a first embodiment of a carbon dioxide gas separation apparatus according to the present invention. FIG. 2 is a schematic diagram showing a modified example of the first embodiment of the carbon dioxide gas separation apparatus according to the present invention. FIG. 3 is a schematic diagram (part 1) showing a schematic configuration example of a water separation unit incorporated in the carbon dioxide gas separation apparatus shown in FIG. 1 and its operation. FIG. 4 is a schematic diagram (part 2) showing a schematic configuration example of a water separation unit incorporated in the carbon dioxide gas separation apparatus shown in FIG. 1 and its operation. FIG. 5 is a schematic diagram showing a second embodiment of a carbon dioxide gas separation apparatus according to the present invention. FIG. 6 is a schematic diagram showing a third embodiment of a carbon dioxide gas separation apparatus according to the present invention. FIG. 7 is a schematic diagram showing an example of use of a fourth embodiment of a carbon dioxide gas separation apparatus according to the present invention. FIG. 8 is a schematic diagram showing a fifth embodiment of a carbon dioxide gas separation apparatus according to the present invention.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A carbon dioxide gas separation apparatus according to an embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1(A) is a schematic diagram showing a first embodiment of a carbon dioxide gas separation apparatus.

[0014] In the present invention, as a method for separating carbon dioxide gas, a first gas (e.g., oxygen) and a second gas (e.g., fuel) containing carbon are supplied to a reaction section, which is a combustion section, to cause a reaction (combustion), and carbon dioxide gas (CO ) is separated from the generated (combustion) gas (exhaust gas) that is discharged. ２ ) from the generated gas. ２There are various methods for separating and recovering carbon dioxide (O ２ ), and when the second gas is used as fuel, by reacting (burning) them, a generated gas containing a high concentration of carbon dioxide gas (carbon dioxide) with less nitrogen is discharged compared to the device and method that burns air and fuel, and this is further concentrated to produce carbon dioxide gas (CO ２ ) is separated and recovered using an oxygen combustion method.

[0015] [First embodiment] As shown in FIG. 1(A), the carbon dioxide gas separation device of the first embodiment separates a first gas, oxygen (O ２ a first gas supply unit (oxygen supply unit) 10A that supplies a fuel F that is a second gas; a combustion furnace 12A that is a reaction furnace to which dry oxygen from the first gas supply unit (oxygen supply unit) 10A is supplied and which reacts (combusts) with the fuel F that is the second gas; and a combustion furnace 12B that extracts moisture (H) from a combustion gas G4 that is a product gas containing moisture and carbon dioxide gas and is generated in the reaction furnace 12A. ２ The combustion unit 12 is a reaction unit equipped with a dehumidifier 40 that separates moisture (O) from the exhaust gas G5, which is a dehumidified product gas discharged from the dehumidifier 40 of the combustion unit 12, and a moisture separation unit 15 that separates moisture remaining in the exhaust gas G5.

[0016] The moisture separation section 15 is provided between the first gas supply section (oxygen supply section) 10A and the combustion furnace 12A, and is equipped with a first gas inlet 15a for introducing dry oxygen G2, which is a dry first gas supplied from the first gas supply section (oxygen supply section) 10A, a first gas outlet 15b for discharging a first gas (oxygen) G3 containing moisture into the combustion section 12A, an exhaust gas inlet 15c for introducing an exhaust gas G5 containing at least moisture and carbon dioxide gas exhausted from the combustion section 12, and an exhaust gas outlet 15d for discharging a dry exhaust gas G6 from which moisture has been removed.

[0017] As shown in FIG. 1A, the carbon dioxide gas separation device 1 of this embodiment includes an oxygen supply unit 10A that takes in air G1 from the outside and generates oxygen, a combustion unit 12 that is supplied with oxygen from the oxygen supply unit 10A and has a combustion furnace 12A that performs combustion together with supplied fuel, and a moisture separation unit 15 that is supplied with exhaust gas G5 discharged from the combustion unit 12 and separates moisture from the exhaust gas G5.

[0018] The oxygen supply section 10A, the combustion section 12, and the moisture separation section 15 are connected via connection lines 20, 21, 22A, and 22B, which are, for example, tubular pipes, and are configured to supply the gas processed and generated in each section to the downstream section.

[0019] Specifically, the components and connecting lines are as follows. Between the oxygen supply unit 10A and the moisture separation unit 15, a connecting line 20 is installed, which supplies dry oxygen G2 (mainly oxygen (O2), but may also contain other substances such as argon (Ar), as long as it has a higher oxygen concentration than air) generated in the oxygen supply unit 10A to the moisture separation unit 15. Between the moisture separation unit 15 and the combustion furnace 12A provided in the combustion unit 12, a connecting line 21 is installed, which supplies oxygen G3 (which may contain other substances such as water and argon) that has been dehumidified using an adsorbent provided inside the moisture separation unit 15, as described below, to the combustion unit 12. The combustion unit 12 is also equipped with a dehumidifier 40, and between the dehumidifier 40 and the combustion furnace 12A, a connecting line 22A is installed, which supplies combustion gas G4 (which contains carbon dioxide and moisture, but may also contain other substances such as nitrogen and argon) generated in the combustion furnace 12A to the dehumidifier 40. Furthermore, a connection line 22B is installed between the dehumidifier 40 and the moisture separation section 15, which supplies exhaust gas G5 (which may contain other substances such as nitrogen and argon in addition to carbon dioxide and moisture) exhausted from the dehumidifier 40 and containing at least moisture and carbon dioxide to the moisture separation section 15.

[0020] The oxygen supply unit 10A may be any device capable of separating oxygen from the taken-in air G1 (nitrogen to oxygen ratio of approximately 8:2) and supplying the separated oxygen to the moisture separation unit 15. For example, it may be configured with a known device such as a PSA (Pressure Swing Adsorption) oxygen gas generator, a PVSA (Pressure Vacuum Swing Adsorption) oxygen gas generator, or a VSA (Vacuum Swing Adsorption) oxygen gas generator. Such devices change the gas pressure to repeatedly adsorb and desorb gas, and use an adsorbent to remove nitrogen gas (N) and other gases from the air, separating high-concentration (preferably 90 to 95% or more) dry oxygen gas and supplying it to the moisture separation unit 15.

[0021] The oxygen supply unit 10A is not limited in configuration as long as it can generate dry oxygen. For example, by using a method for generating liquefied oxygen, such as a cryogenic separation device, it is possible to supply oxygen to the water separation unit 15 at an oxygen concentration of approximately 99.9%. Furthermore, the dryness of the oxygen to be supplied is preferably a dew point of -50°C or less so that the adsorbent provided in the water separation unit 15 can be efficiently dried.

[0022] The oxygen G2 (dry oxygen) separated in the oxygen supply unit 10A is supplied to the moisture separation unit 15 via the connection line 20. As will be described later, the moisture separation unit 15 has a function of not reducing the amount of moisture adsorbed in the exhaust gas G5 discharged from the combustion unit 12 and supplied via the connection line 22B (a function of continuously separating and recovering high-concentration carbon dioxide gas) by using the oxygen supplied from the oxygen supply unit 10A. In other words, the moisture separation unit 15 has a function of separating moisture from the exhaust gas while drying the adsorbent with the oxygen supplied from the oxygen supply unit 10A.

[0023] The oxygen supplied to the moisture separation section 15 is also supplied to the combustion furnace 12A of the combustion section 12 via a connection line 21. In the combustion furnace 12A, oxygen and fuel supplied from an external source are combusted to obtain the required thermal energy. The fuel supplied to the combustion furnace 12A may be any fuel containing carbon so as to produce exhaust gas containing carbon dioxide, and examples of such fuel include hydrocarbon gas, coal, and petroleum. In this case, the combustion furnace 12A may be a type that burns fuel while supplying oxygen containing a certain amount of moisture that has passed through the moisture separation section 15 so as to increase the concentration of carbon dioxide in the exhaust gas (oxygen combustion method). Examples of such a combustion furnace 12A include an oxygen burner, a boiler, and an engine.

[0024] The combustion gas G4 generated by combustion in the combustion furnace 12A contains carbon dioxide, moisture, and other components, and this combustion gas G4 is supplied to the moisture separation unit 15 via the dehumidifier 40 and the connection line 22B to which the pump 22p is installed. As described above, moisture is adsorbed from the exhaust gas G5 supplied to the moisture separation unit 15 by the adsorbent provided therein, and dried and highly concentrated dried exhaust gas G6 (carbon dioxide) can be separated. The carbon dioxide separated here is then discharged via the discharge line 24.

[0025] Therefore, the moisture separation section 15 is equipped with an oxygen inlet (first gas inlet) 15a for introducing dry oxygen G2 supplied from the oxygen supply section 10A, an oxygen outlet 15b for discharging moisture-containing oxygen G3 to the combustion section 12, an exhaust gas inlet 15c for introducing exhaust gas G5 exhausted from the combustion section 12, and an exhaust gas outlet 15d for discharging dry exhaust gas G6.

[0026] 1B, a circulation line (piping) 22C for the combustion gas G4 may be provided to introduce a portion G4-1 of the combustion gas G4 discharged from the combustion furnace 12A into the combustion furnace 12A. This circulation line 22C branches off from the connection line 22A connecting the combustion furnace 12A and the dehumidifier 40 just before the humidifier 40 and is connected to the connection line 21. A pump 22Cp is installed in this circulation line 22C to circulate the portion G4-1 of the combustion gas G4 to the combustion furnace 12A.

[0027] Typically, in the oxyfuel combustion method, combustion is performed in the combustion furnace 12A using oxygen gas from which nitrogen has been removed and fuel, which increases the combustion temperature and may damage the combustion furnace 12A. Therefore, by providing the circulation line 22C described above and returning a portion G4-1 of the combustion gas (carbon dioxide gas containing moisture) G4 to the combustion furnace 12A, the combustion temperature can be lowered. As a result, damage to the combustion furnace 12A can be suppressed. Furthermore, modifications to prevent damage to the combustion furnace can be eliminated. The circulation line 22C may also be omitted (see Figures 1A, 2, and 3).

[0028] 2 and 3 are schematic diagrams illustrating an example of the configuration of the moisture separation unit 15 according to this embodiment and its operation. The moisture separation unit 15 of this embodiment uses a PSA dehumidifier (a dehumidifying PSA). The moisture separation unit 15 includes multiple (two in this embodiment) dehumidifying towers (a first dehumidifying tower 15A and a second dehumidifying tower 15B). Each of the first dehumidifying tower 15A and the second dehumidifying tower 15B is provided with an adsorption unit equipped with an adsorbent (e.g., a solid adsorbent such as zeolite or silica gel). Each of the dehumidifying towers (adsorption units) 15A and 15B includes an oxygen inlet, an oxygen outlet, an exhaust gas inlet, and an exhaust gas outlet. An on-off valve, as described below, is installed at each of the oxygen inlet, oxygen outlet, exhaust gas inlet, and exhaust gas outlet.

[0029] The first dehumidifying tower 15A and the second dehumidifying tower 15B of this embodiment are provided with a switching structure that allows switching so that dry oxygen G2 from the oxygen supply unit 10A is introduced into one of them to dry the adsorbent, and exhaust gas G5 from the combustion furnace 12A is introduced into the other. Note that the dehumidifying device may be a set of the first dehumidifying tower 15A and the second dehumidifying tower 15B as in this embodiment, and multiple sets of this device may be used.

[0030] The configuration of the switching structure will be described below. A connection line 20 and a branch line formed in the connection line 22B are connected to each dehumidification tower (first dehumidification tower 15A, second dehumidification tower 15B). Specifically, the connection line 20 has branch lines 20a and 20b, which are connected to the first dehumidification tower 15A and the second dehumidification tower 15B, respectively. The connection line 22B has branch lines 22a and 22b, which are connected to the first dehumidification tower 15A and the second dehumidification tower 15B, respectively.

[0031] Furthermore, each of the first dehumidifying tower 15A and the second dehumidifying tower 15B is connected to a connection line 21 and a branch line formed in the discharge line 24. Specifically, the connection line 21 has branch lines 21a and 21b, which are connected to the first dehumidifying tower 15A and the second dehumidifying tower 15B, respectively. Furthermore, the discharge line 24 has branch lines 24a and 24b, which are connected to the first dehumidifying tower 15A and the second dehumidifying tower 15B, respectively.

[0032] The branch lines 20a, 20b and 22a, 22b are provided with on-off valves 30a, 31a and on-off valves 30b, 31b, respectively. The branch lines 21a, 21b and 24a, 24b are provided with on-off valves 30c, 31c and on-off valves 30d, 31d, respectively. In this case, in Figures 2 and 3, the open states of the on-off valves 30a, 31a, 30b, 31b, 30c, 31c, and 30d, 31d are indicated by black fill, and the closed states are indicated by white fill.

[0033] Here, the operation of the first dehumidifying tower 15A and the second dehumidifying tower 15B and the open / close states of the valves constituting the switching structure will be described. Figure 2 is a schematic diagram showing the first dehumidifying tower 15A in a drying process (a process in which moisture is adsorbed from moist exhaust gas by an adsorbent) and the second dehumidifying tower 15B in a humidifying process (a process in which moisture is desorbed from the adsorbent by dry oxygen and the adsorbent is regenerated).

[0034] 2, the on-off valve 30a of the first dehumidifying tower 15A is closed and the on-off valve 30b is open, so that the first dehumidifying tower 15A is not supplied with dry oxygen G2 from the oxygen supply unit 10A, but is supplied with combustion gas G4 from the combustion furnace 12A via the connection line 22B and the branch line 22a. The exhaust gas G5, which contains at least moisture and carbon dioxide and is supplied after passing through the dehumidifier 40, has moisture adsorbed by the adsorbent in the first dehumidifying tower 15A (drying step), and the high-concentration carbon dioxide is discharged (recovered) via the branch line 24a and the discharge line 24 through the open on-off valve 30d.

[0035] In this case, the concentration of the dried carbon dioxide gas G6 discharged through the discharge line 24 is preferably, for example, 30% or more. In addition, since the on-off valve 30c is closed, exhaust gas containing a high concentration of carbon dioxide gas will not flow into the connection line 21 (combustion furnace 12A).

[0036] During the operation of the first dehumidifying tower 15A described above, the on-off valve 31a of the second dehumidifying tower 15B is open, so that dry oxygen (O ２ ) G2 is supplied. In this state, the supplied oxygen is in a dry state, so the moisture contained in the adsorbent in the dehumidifying tower 15B is desorbed (humidification process). In addition, since the on-off valve 31b of the dehumidifying tower 15B is closed, exhaust gas G5 from the combustion furnace 12A does not flow into the dehumidifying tower 15B in the humidification process.

[0037] In this embodiment, the first dehumidifying tower 15A, which is one of the first and second dehumidifying towers 15A and 15B that are components of the moisture separating unit 15, receives dry oxygen (O２ ) G2 is introduced into the second dehumidifying tower 15B to dry the adsorbent, and exhaust gas G5 is introduced into the other second dehumidifying tower 15B to adsorb moisture.

[0038] Generally, when a dehumidifying tower into which exhaust gas is introduced is continuously operated, the amount of moisture adsorbed by the adsorbent decreases, which may result in a decrease in the concentration of carbon dioxide gas (carbon dioxide) that is separated and recovered. In this embodiment, the dehumidifying tower that performs such a drying process and a humidifying process has a switching structure. By switching using this switching structure, the concentration of carbon dioxide gas (carbon dioxide) in the dried exhaust gas G6 that is separated and recovered is not decreased.

[0039] That is, as shown in Fig. 3, by switching the open / close states of the eight on-off valves 30a to 30d and the on-off valves 31a to 31d shown in Fig. 2 inversely, the drying process is carried out in the second dehumidifying tower 15B, and the humidifying process is carried out in the first dehumidifying tower 15A. Such switching between the first dehumidifying tower 15A and the second dehumidifying tower 15B is carried out continuously. As a result, the dry oxygen (O ２ By using a dehumidifying tower equipped with an adsorbent dried by the dehumidifying tower G2, it becomes possible to continue adsorbing moisture from the exhaust gas G5. By performing such a switching operation, the amount of moisture adsorbed in the exhaust gas G5 does not decrease, and the concentration of carbon dioxide gas emitted does not decrease.

[0040] The timing of switching the dehumidifying towers can be changed as appropriate depending on the amount of oxygen supplied from the oxygen supply unit 10A, the dryness, the moisture content of the exhaust gas G5 discharged from the combustion furnace 12A, etc. In this case, for example, the switching operation may be performed at regular intervals after the device has started operating. Alternatively, the moisture content of the dried exhaust gas G6 discharged from the moisture removal device 15 may be detected by a detection means (not shown) and the switching may be performed when the moisture content reaches a certain value (for example, the dew point is −40° C.) or higher.

[0041] According to the above-described configuration, dry oxygen (O ２) G2 to dry the wet exhaust gas G5 discharged from the combustion furnace 12A, enabling efficient and economical dehumidification and reducing the power required to separate and recover carbon dioxide. Specifically, in this embodiment, focusing on the dry oxygen supplied from the oxygen supply unit 10A for combustion, this oxygen is used to alternately dry the adsorbent by switching between multiple dehumidification towers (first dehumidification tower 15A, second dehumidification tower 15B) that are components of the moisture separation unit 15, thereby improving the efficiency of the device configuration and reducing energy consumption. Furthermore, since there is no need to install a dedicated dehumidification device for exhaust gas, there is no increase in energy consumption, and the overall device does not become larger.

[0042] The moisture separation section 15 may be configured to dry the exhaust gas, and may be configured using a PSA system as in this embodiment, a VSA system, a TSA (Thermal Swing Adsorption) system, a membrane separation system, or a combination of these systems. Since the moisture separation section 15 only needs to dry the exhaust gas, it can be configured in any suitable manner, such as by using a single dehumidifying tower in a rotating system, in addition to a system that switches between multiple towers, and the number of dehumidifying towers is not limited.

[0043] In addition, the dehumidifier 40 generally has the effect of cooling the combustion gas G4, and can separate the moisture in the combustion gas G4 and increase the concentration of carbon dioxide in the combustion gas G4, thereby making it possible to reduce the power required to separate the carbon dioxide.

[0044] In this embodiment, the first gas is described as oxygen, but the present invention is not limited to this. Examples of gases containing oxygen atoms other than oxygen include ozone, nitrous oxide, nitric oxide, nitrogen dioxide, chlorine dioxide, and oxygen difluoride. Examples of fuels include hydrocarbons, natural gas, alcohol, petroleum, and coal. Examples of alcohols include methanol, ethanol, propanol, and isopropanol.

[0045] The dehumidifier may be a device that separates moisture by gas-liquid separation through cooling, or may be a device that separates moisture using a membrane that selectively allows moisture to pass through.

[0046] The carbon dioxide separation method of this embodiment includes a reaction process in which a reaction is carried out in a combustion section 12, which is a reaction section, using dry oxygen G2, which is a dry first gas supplied from a first gas supply section 10A, and fuel F, which is a second gas supplied from a second gas supply section; a drying process in which exhaust gas G5, which is a product gas emitted in this reaction process, is passed through a moisture separation section 15 to separate moisture; and a humidification process in which dry oxygen G2, which is a dry first gas, is passed through the moisture separation section 15 to humidify it.

[0047] According to the carbon dioxide separation method of this embodiment, moisture is separated and recovered from the exhaust gas discharged in the combustion process in the drying process, and high-concentration carbon dioxide is discharged. In this drying process, moisture is supplied to the moisture separation section 15, but moisture is removed from the moisture separation section by dry oxygen supplied from the oxygen supply section 10A in the humidification process, so moisture separation performance does not deteriorate. In other words, in the moisture separation process, moisture is efficiently separated from the exhaust gas with a simple structure that simply passes the exhaust gas through the moisture separation section, so no large power is required and the entire carbon dioxide separation device can be made smaller.

[0048] [Second embodiment] Next, another embodiment of the carbon dioxide gas separation apparatus according to the present invention will be described. In the embodiment described below, parts having the same functions as those in the first embodiment will be given the same reference numerals, and detailed description thereof will be omitted.

[0049] FIG. 4 is a schematic diagram showing a second embodiment of a carbon dioxide gas separation apparatus according to the present invention. The combustion section 12 of this embodiment is characterized by including a circulation line (piping) 22D for exhaust gas G5. This circulation line 22D for exhaust gas G5 is arranged to branch off from a connection line 22B installed between the combustion section 12 and the moisture separation section 15. A portion G5-1 of the exhaust gas G5 that has passed through the dehumidifier 40 is circulated to the combustion furnace 12A. The remaining exhaust gas G5 is supplied to the moisture separation section 15. Thus, the circulation line 22D may circulate the exhaust gas inside the combustion section 12, as shown in FIG. 1B, or may circulate the exhaust gas outside the combustion section 12.

[0050] [Third Embodiment] Figure 5 is a schematic diagram showing a third embodiment of a carbon dioxide gas separation apparatus according to the present invention. Parts having the same functions as those in the above-described embodiments are given the same reference numerals, and detailed description thereof will be omitted. In this embodiment, a carbon dioxide gas separation section 42 that further concentrates carbon dioxide gas in the dried exhaust gas G6 discharged from the water separation section 15 is provided in the discharge line 24. This carbon dioxide gas separation section 42 may be any device that can concentrate carbon dioxide gas, and for example, a PSA system, a VSA system, a TSA system, etc. can be used.

[0051] By providing such a carbon dioxide gas separation unit 42, the carbon dioxide gas (CO ２ ) can be made to have a concentration of 99% or more.

[0052] [Fourth Embodiment] Figure 6 is a schematic diagram showing an example of use of the fourth embodiment of the carbon dioxide gas separation device described above. Parts having similar functions to those of the above embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted. As shown in Figure 6, the fourth embodiment shows an example in which the combustion section 12 of the carbon dioxide gas separation device described above is incorporated into the combustion section of a hydrogen production device 50. The hydrogen production device 50 generates hydrogen at high temperatures (in a combustion furnace), and as in the above embodiments, an oxygen combustion method in which oxygen and fuel are introduced can be used to heat the combustion furnace 12A. Therefore, such a hydrogen production device can incorporate the above-mentioned carbon dioxide gas separation device.

[0053] The following is a description of the schematic configuration of such an example of use. As shown in Figure 6, the hydrogen production device 50 includes a compressor 52 that compresses a raw material gas (hydrocarbon fuel) 51, a desulfurizer 53, a reformer 54, a converter 55, and a hydrogen PSA 56.

[0054] The desulfurizer 53 has a function of removing sulfur components contained as an odorant in the raw material gas. Note that the desulfurizer 53 does not need to be provided when raw material gas that does not contain sulfur components is used.

[0055] The reformer 54 has a function of reforming the raw material gas to generate reformed gases such as hydrogen and carbon monoxide by adding steam (or pure water) to the raw material gas and bringing it into contact with a reforming catalyst at high temperatures (for example, 650°C to 900°C), and is housed in the combustion furnace (oxygen combustion furnace) 12A. The reformer 54 uses the raw material gas and off-gas from the hydrogen PSA 56 as fuel gases and combusts them together with oxygen supplied from the oxygen supply unit 10A of the carbon dioxide gas separation unit 1.

[0056] The converter 55 has a function of reacting the carbon monoxide in the reformed gas sent from the reformer 54 with water vapor to produce more hydrogen. In this converter 55, a catalyst such as an Fe-Cr-based, Cu-Zn-based, or Pt-based catalyst is used depending on the reaction temperature, for example, from 200°C to 500°C.

[0057] The hydrogen PSA 56 uses an adsorbent to adsorb gases other than hydrogen, such as carbon monoxide, carbon dioxide, methane, and water vapor, and separates only hydrogen from the shifted gas supplied from the shift converter 55, making it possible to obtain hydrogen 60 that is ultimately concentrated to a concentration of approximately 99.999%. The off-gas OG generated in this hydrogen PSA 56 may be used as fuel for heating the reformer 54.

[0058] As described above, when the combustion furnace 12A using the oxygen combustion method is incorporated into the reformer 54 of the hydrogen production device 50, by applying the carbon dioxide separation device 1 described above, it becomes possible to efficiently separate and recover carbon dioxide gas (carbon dioxide).

[0059] The carbon dioxide gas separation device according to the present invention has been described above, but the present invention is sufficient as long as it can implement at least the following carbon dioxide gas separation method, and the components of the carbon dioxide gas separation device can be modified as appropriate. That is, it is sufficient to have a combustion step in which combustion is performed in combustion section 12 using oxygen and supplied fuel supplied from oxygen supply section 10A, a drying step in which exhaust gas emitted in the combustion step is passed through moisture separation section 15 to separate moisture, and a humidification step in which oxygen supplied from the oxygen supply section is passed through the moisture separation section to humidify the oxygen.

[0060] The present invention can also be applied to various gas separation devices that supply oxygen and fuel to perform combustion and separate carbon dioxide from exhaust gas, and for example, the present inventor has proposed Patent Application No. 2023-168972. It can be applied to the gas separation device.

[0061] [Fifth embodiment] Figure 7 is a schematic diagram showing a fifth embodiment of a carbon dioxide gas separation apparatus according to the present invention. Parts having the same functions as those in the above embodiments are given the same reference numerals, and detailed description thereof will be omitted. As shown in Figure 7, in the carbon dioxide gas separation apparatus 1 of the fifth embodiment, the fuel supply unit 10B and the oxygen supply unit 10A are installed in the reverse order in the carbon dioxide gas separation apparatus 1 of Figure 1. In other words, when a gas containing hydrogen atoms (fuel F) is used as the first gas, a gas containing oxygen atoms is used as the second gas.

[0062] As shown in FIG. 7, the carbon dioxide gas separation device 1 of the fifth embodiment includes a fuel supply unit 10B which is a first gas supply unit that supplies fuel F, and an oxygen O ２ the combustion furnace 12A, which is a reaction furnace to which oxygen from the oxygen supply unit 10A is supplied and which undergoes a reaction (combustion) together with fuel; the combustion unit 12, which is a reaction unit equipped with a dehumidifier 40 that separates moisture from combustion gas G4, which is generated in the combustion furnace 12A and contains moisture and carbon dioxide; and the moisture separation unit 15, which is introduced with exhaust gas G5, which is a dehumidified product gas discharged from the combustion unit 12, and which separates moisture remaining in the exhaust gas G5.

[0063] The moisture separation section 15 is provided between the fuel supply section 10B and the combustion furnace 12A, and includes a fuel inlet (first gas inlet) 15e for introducing the dry first gas (fuel) supplied from the first gas (fuel) supply section, a fuel outlet (first gas outlet) 15f for discharging the first gas (fuel) containing moisture to the reaction section 12A, an exhaust gas inlet 15c for introducing the exhaust gas G5 containing at least moisture and carbon dioxide gas that is exhausted from the reaction section 12A, and an exhaust gas outlet 15d for discharging the dry exhaust gas from which moisture has been removed.

[0064] Here, the dryness of the supplied fuel F is preferably a dew point of -50°C or less so that the adsorbent provided in the water separation unit 15 can be efficiently dried. The function and effect of the water separation unit 15 are the same as in the first embodiment. According to this embodiment, it is possible to efficiently separate water from exhaust gas containing carbon dioxide.

[0065] The present invention is widely applicable to carbon dioxide gas separation apparatuses and carbon dioxide gas separation methods in general.

[0066] 1 Carbon dioxide separation device 10A Oxygen supply section 10B Fuel supply section 12 Combustion section (reaction section) 12A Combustion furnace (reaction furnace) 15 Moisture separation section 15A First dehumidification tower 15B Second dehumidification tower 15a Oxygen inlet (first gas inlet) 15b Oxygen outlet (first gas outlet) 15c Exhaust gas inlet (produced gas inlet) 15d Exhaust gas outlet (produced gas outlet) 15e Fuel inlet (first gas inlet) 15f Fuel outlet (first gas outlet) 20C Circulation line for combustion gas G4 20D Circulation line for exhaust gas G6 40 Dehumidifier (moisture separation section) 42 Carbon dioxide separation section 50 Hydrogen production device G1 Air G2 Dry oxygen G3 Moisture-containing oxygen (first gas) G4 Combustion gas (produced gas) G5 Exhaust gas (product gas) G6 Dry exhaust gas (dry product gas (CO ２ )) OG Offgas

Claims

1. A carbon dioxide gas separation device comprising: a first gas supply unit that supplies a dry first gas; a second gas supply unit that supplies a second gas; a reaction furnace that receives the dry first gas from the first gas supply unit and reacts with the second gas; and a dehumidifier that separates moisture from a product gas produced in the reaction furnace, the product gas containing moisture and carbon dioxide; and a moisture separation unit that receives dehumidified product gas discharged from the dehumidifier in the reaction unit and separates moisture remaining in the dehumidified product gas, the moisture separation unit being located between the first gas supply unit and the reaction furnace and comprising: a first gas inlet that introduces the dry first gas supplied from the first gas supply unit; a first gas outlet that discharges the moisture-containing first gas into the reaction furnace; a product gas inlet that introduces the dehumidified product gas that is discharged from the reaction unit and contains at least moisture and carbon dioxide; and a product gas outlet that discharges the dry product gas from which moisture has been removed.

2. The carbon dioxide separation device described in claim 1, characterized in that the moisture separation section has a plurality of adsorption sections each equipped with an adsorbent that adsorbs moisture, and each adsorption section has the first gas inlet, the first gas outlet, the generated gas inlet, and the generated gas outlet.

3. The carbon dioxide gas separation apparatus according to claim 1, further comprising a circulation line for introducing a portion of the generated gas into the reactor.

4. A carbon dioxide gas separation apparatus according to claim 1, further comprising a circulation line for introducing a portion of the dehumidified product gas into the reactor.

5. A carbon dioxide gas separation apparatus according to claim 1, further comprising a carbon dioxide gas separation section for further increasing the concentration of carbon dioxide gas from the dried product gas containing carbon dioxide gas discharged from the water separation section.

6. The carbon dioxide gas separation device according to claim 1, wherein the reaction section is incorporated into a hydrogen production device.

7. A carbon dioxide gas separation method comprising: a reaction step in which a reaction is carried out in a reaction section using a dry first gas supplied from a first gas supply section and a second gas supplied from a second gas supply section; a drying step in which moisture is separated from the product gas discharged in the reaction step by passing it through a moisture separation section; and a humidification step in which moisture is humidified by passing the dry first gas through a moisture separation section.

8. A carbon dioxide separation method as described in claim 7, characterized in that the moisture separation process alternately introduces the dry first gas and the reaction gas into each of multiple adsorption sections equipped with an adsorbent that adsorbs moisture.

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