Carbon dioxide separation device and combustion system including same

Abstract

A carbon dioxide separation device 100 disclosed in the present invention comprises: a steam generation source 110 that generates steam used for sweep gas; a separation part 130 including a separation membrane 133 that selectively transmits carbon dioxide, and a first space 131 and a second space 132 that are partitioned by the separation membrane 133; a first flow channel 181 through which a mixed gas that contains carbon dioxide is channeled so as to pass through the first space 131; a second flow channel 182 through which a sweep gas that contains steam is guided to the second space 132; a third flow channel 183 through which a carbon-dioxide-containing sweep gas that is generated in the second space 132 and contains steam and carbon dioxide flows; a decompression pump 140 disposed in the third flow channel 183; and a decompression part 121 disposed in the second flow channel 182. The sweep gas is decompressed in the decompression part 121 and supplied to the second space 132.

Description

Carbon dioxide separation device and combustion system including the same

[0001] The present disclosure relates to a carbon dioxide separation device and a combustion system including the same.

[0002] In recent years, there has been an increasing demand for carbon dioxide capture in various facilities that generate carbon dioxide. Therefore, various proposals have been made regarding carbon dioxide separation and capture technologies using separation membranes.

[0003] Claim 1 of Patent Document 1 (JP 2021-159813 A) describes a carbon dioxide separation and capture device that includes: a carbon dioxide separator configured to selectively allow carbon dioxide contained in a carbon dioxide-containing gas flowing into a first space to pass through a separation membrane to a second space; a water storage section that stores water and is provided in a space having a substantially sealed structure that communicates with the second space; a pump that decompresses the second space; and a water separator that separates water from gas discharged from an outlet of the pump.

[0004] Claim 1 of Patent Document 2 (JP 2022-127006 A) describes a separator having an internal space partitioned into a first space configured by a separation membrane having a property in which the permeation rate of carbon dioxide increases as the moisture content in the membrane increases, and a second space configured by a separation membrane having a property in which a carbon dioxide-containing gas flows in from a carbon dioxide-containing gas supply channel and a non-permeating gas that does not permeate the separation membrane flows out into a non-permeating gas channel, and a second space configured by a permeating gas that permeates the separation membrane flows out into a permeating gas channel; a condenser provided in the carbon dioxide-containing gas supply channel and configured to condense moisture in the carbon dioxide-containing gas and remove condensed water from the carbon dioxide-containing gas; a vaporizer thermally connected to the condenser and communicating with the second space via a sweep gas supply channel and configured to vaporize water inside the condenser to generate a water vapor-containing gas to be supplied to the second space; a water supply source configured to supply water to the vaporizer so that water in the vaporizer does not run out; a temperature detector configured to detect the temperature of the separator; and a supply pump provided in one of the non-permeable gas flow paths and configured to pass the carbon dioxide-containing gas through the first space of the separation membrane; a pressure reduction pump provided in the permeable gas flow path and configured to reduce the pressure in the second space to promote vaporization of water inside the vaporizer and promote carbon dioxide contained in the carbon dioxide-containing gas to permeate the separation membrane and flow out of the permeable gas into the permeable gas flow path; and a controller configured to operate the pressure reduction pump even when a stop signal is input, until the temperature detected by the temperature detector falls to a predetermined temperature lower than the current temperature, and to stop the pressure reduction pump when the temperature detected by the temperature detector falls to the predetermined temperature, and when the temperature detected by the temperature detector falls to the predetermined temperature, the controller is configured to change the predetermined temperature to a value lower than the temperature at that time after the pressure reduction pump is stopped, and to operate the pressure reduction pump until the temperature detected by the temperature detector falls to the changed predetermined temperature.

[0005] JP 2021-159813 A JP 2022-127006 A

[0006] In a carbon dioxide separator using a carbon dioxide permeable separation membrane, it is preferable to supply water vapor as a sweep gas. However, there are various types of water vapor generation sources, and a new carbon dioxide separator that can be used with various water vapor generation sources is needed. In this situation, one of the objects of the present disclosure is to provide a new carbon dioxide separator that can be used with various water vapor generation sources, and a combustion system including the same.

[0007] One aspect of the present disclosure relates to a carbon dioxide separation apparatus for separating carbon dioxide from a mixed gas containing carbon dioxide, the carbon dioxide separation apparatus including: a water vapor generation source for generating water vapor to be used as a sweep gas; a separation unit including a separation membrane selectively permeable to carbon dioxide and a first space and a second space partitioned by the separation membrane; a first flow path for flowing the mixed gas through the first space; a second flow path for introducing the water vapor-containing sweep gas into the second space; a third flow path for flowing a carbon dioxide-containing sweep gas generated in the second space and containing the water vapor and carbon dioxide; a pressure reduction pump disposed in the third flow path; and a pressure reduction unit disposed in the second flow path, wherein the sweep gas is reduced in pressure in the pressure reduction unit and supplied to the second space.

[0008] Another aspect of the present disclosure relates to a combustion system including the carbon dioxide separation device according to the present disclosure, wherein the steam generation source generates the steam by utilizing thermal energy generated by burning fuel, and the mixed gas includes exhaust gas generated when the fuel is burned.

[0009] According to the present disclosure, a new carbon dioxide separation device that can be used with various water vapor generation sources and a combustion system including the same are provided.

[0010] FIG. 1 schematically shows the configuration of an example of a carbon dioxide separator according to the first embodiment. FIG. 2 schematically shows the configuration of another example of a carbon dioxide separator according to the first embodiment. FIG. 3 schematically shows the configuration of another example of a carbon dioxide separator according to the first embodiment. FIG. 4 schematically shows the configuration of another example of a carbon dioxide separator according to the first embodiment. FIG. 5 schematically shows the configuration of an example of a combustion system according to the second embodiment. FIG. 6 schematically shows the configuration of another example of a combustion system according to the second embodiment.

[0011] Below, embodiments according to the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and other materials may be applied as long as the invention according to the present disclosure can be implemented. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or more and numerical value B or less." In the following description, when lower and upper limits of numerical values ​​related to specific physical properties or conditions are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit.

[0012] (Carbon dioxide separation device) Hereinafter, the carbon dioxide separation device according to this embodiment may be referred to as "separation device (A)." The separation device (A) is a carbon dioxide separation device that separates carbon dioxide from a mixed gas containing carbon dioxide. The separation device (A) includes: a water vapor generation source that generates water vapor to be used for the sweep gas; a separation section including a separation membrane that is selectively permeable to carbon dioxide and a first space and a second space partitioned by the separation membrane; a first flow path that flows the mixed gas through the first space; a second flow path that introduces the water vapor-containing sweep gas to the second space; a third flow path through which a carbon dioxide-containing sweep gas that is generated in the second space and contains water vapor and carbon dioxide flows; a pressure reduction pump disposed in the third flow path; and a pressure reduction section disposed in the second flow path. The sweep gas is reduced in pressure in the pressure reduction section and supplied to the second space.

[0013] Hereinafter, the water vapor generated in the water vapor generation source may be referred to as "water vapor W." The mixed gas and the carbon dioxide-containing sweep gas contain carbon dioxide (carbon dioxide gas).

[0014] A sweep gas containing water vapor W flows into the second space of the separation section through the second flow path. The sweep gas flowing into the second space can be interpreted as a water vapor-containing gas. The sweep gas flowing into the second space is mixed with carbon dioxide that has permeated the separation membrane, becoming a carbon dioxide-containing sweep gas. The carbon dioxide-containing gas is discharged from the second space through the third flow path. When a specific separation membrane (e.g., a separation membrane using a specific organic compound) is used, the separation performance of the separation section can be significantly improved by using a gas containing water vapor as the sweep gas.

[0015] If the water vapor W generated in the water vapor generation source is at a high temperature, the introduction of a high-temperature sweep gas into the second space reduces the separation performance in the separation section and accelerates the deterioration of the separation membrane. Furthermore, if the water vapor W is at a high pressure, the introduction of a high-pressure sweep gas into the second space reduces the separation performance in the separation section. Therefore, conventional carbon dioxide separation devices have had the problem of being unable to be used depending on the type of water vapor generation source.

[0016] On the other hand, the separation device (A) includes a pressure reducing section disposed between the steam generation source and the second space. Therefore, even if the steam W is at a high pressure, it can be used as a sweep gas. Furthermore, if the temperature of the steam W is reduced by reducing the pressure of the steam W, the steam W can be used as a sweep gas even if it is at a high temperature. Therefore, the separation device (A) can use the steam W generated by various steam generation sources as a sweep gas.

[0017] The temperature T of the sweep gas (water vapor-containing gas) supplied to the second space can be adjusted by the pressure reduction section (or the pressure reduction section and the cooling section described below). The temperature T of the sweep gas supplied to the second space may be less than 100°C. Supplying a sweep gas of less than 100°C to the second space can particularly suppress deterioration of the separation membrane. It also makes it easier to use a separation membrane using an organic compound as the separation membrane. The temperature T may be 80°C or less, or 60°C or less. The temperature T may be 20°C or more. The temperature T may be 30°C or more, or 40°C or more. The temperature T may be 40°C or more and less than 100°C, or may be in the range of 40 to 80°C (for example, 40 to 60°C).

[0018] The relative humidity of the sweep gas supplied to the second space may be 50% RH or higher (e.g., 80% RH or higher or 90% RH or higher). Saturated water vapor may be supplied as the sweep gas to the second space. For example, saturated water vapor at a temperature of less than 100°C may be supplied as the sweep gas to the second space.

[0019] The pressure reduction section is not particularly limited as long as it can reduce the pressure of the steam W generated in the steam generation source. The pressure reduction section may include a pressure reduction valve. The pressure reduction valve can reduce the pressure of the steam generated in the steam generation source. Furthermore, it is also possible to cool the steam by gas expansion during pressure reduction. If the steam is cooled to a desired temperature by cooling it due to gas expansion, the separation apparatus (A) does not need to include a cooling section. The pressure reduction section may include a pressure reduction valve with an adjustable opening. Adjusting the opening is expected to have the effect of controlling the flow rate of the sweep gas and preventing the supply of excessive steam. The pressure reduction section may be equipped with pressure gauges on both sides. Measuring the pressure difference between both sides is expected to have the effect of making it possible to calculate the amount of steam to be supplied.

[0020] The separation apparatus (A) may include a cooling section separate from the pressure reduction section. For example, the separation apparatus (A) may include a pressure reduction section disposed in the second flow path and a cooling section disposed in the second flow path downstream of the pressure reduction section. As described above, a pressure reduction valve may be used for the pressure reduction section. That is, the separation apparatus (A) may further include a cooling section disposed in the second flow path downstream of the pressure reduction valve. Alternatively, the separation apparatus (A) may include a cooling section and a pressure reduction section disposed downstream of the cooling section. Hereinafter, the pressure reduction section and the cooling section disposed downstream of the pressure reduction section may be collectively referred to as the "pressure reduction / cooling section." Furthermore, the cooling section and the pressure reduction section disposed downstream of the cooling section may be collectively referred to as the "pressure reduction / cooling section." The separation apparatus (A) may include multiple pressure reduction sections or multiple cooling sections. The cooling section is not particularly limited, and a known cooler may be used. For example, an indirect cooler or a desuperheater may be used as the cooler.

[0021] In the separation device (A), the hot water obtained in the cooling section may be used as part of the water source for generating steam. With this configuration, the waste heat generated in the cooling section can be effectively utilized.

[0022] The hot water obtained in the cooling section may be cooling water heated by being used to cool the sweep gas in the cooling section. Alternatively, the hot water obtained in the cooling section may be water (drain water) produced by condensation of water vapor in the sweep gas cooled in the cooling section. That is, water produced by condensation of water vapor W in the cooling section may be used as part of the water source for the water vapor generation source. The temperature of the hot water obtained in the cooling section is not particularly limited, but is preferably 40°C or higher (e.g., 60°C or higher).

[0023] The separation apparatus (A) may include a gas-liquid separation section disposed in the third flow path. For example, the separation apparatus (A) may further include a cooling / gas-liquid separation section disposed in the third flow path, which cools the carbon dioxide-containing sweep gas and performs gas-liquid separation (separation of gas and liquid). The cooling / gas-liquid separation section may include a gas-liquid separation section and a cooling section disposed upstream of the gas-liquid separation section. The cooling / gas-liquid separation section may be disposed in the third flow path between the separation section and the decompression pump, or may be disposed in the third flow path downstream of the decompression pump. The separation apparatus (A) may include a cooling / gas-liquid separation section disposed in the third flow path between the separation section and the decompression pump, and a cooling / gas-liquid separation section disposed in the third flow path downstream of the decompression pump. In the cooling section, the carbon dioxide-containing sweep gas is cooled, thereby converting at least a portion of the water vapor in the carbon dioxide-containing sweep gas into water. Then, in the gas-liquid separation section, the gas and liquid are separated. That is, in the cooling / gas-liquid separation section, the carbon dioxide-containing sweep gas is separated into a gas containing carbon dioxide and a liquid containing water. The separation device (A) may further include a heat pump in addition to the cooling / gas-liquid separation section arranged in the third flow path. The heat pump recovers thermal energy from the carbon dioxide-containing sweep gas in the cooling / gas-liquid separation section and supplies the recovered thermal energy to the water vapor generation source. The thermal energy supplied to the water vapor generation source is used to generate water vapor.

[0024] The cooling unit, gas-liquid separator, and heat pump are not particularly limited, and known cooling units, gas-liquid separators, and heat pumps may be used. By using a heat pump, exhaust heat generated in the cooling / gas-liquid separator can be effectively utilized.

[0025] The separation apparatus (A) may include a cooling section that cools the mixed gas flowing into the first space. The cooling section that cools the mixed gas is not particularly limited, and a known cooler may be used. For example, the mixed gas may be cooled using a wet smoke scrubber described in embodiment 2. The temperature T1 of the mixed gas flowing into the first space may be equal to or higher than the temperature T2 of the sweep gas flowing into the second space, may be higher than the temperature T2, may be equal to or lower than the temperature T2, or may be lower than the temperature T2. The temperature T1 of the mixed gas flowing into the first space may be 100°C or lower, 80°C or lower, or 60°C or lower. The temperature T1 may be 20°C or higher, 40°C or higher, or 60°C or higher.

[0026] The separation device (A) may include a water vapor supply mechanism that supplies water vapor to the mixed gas flowing into the first space. The water vapor supply mechanism may be something like the wet smoke scrubber described in embodiment 2. If the humidity is insufficient to achieve the desired performance, water vapor can be added to the mixed gas to supply more moisture to the separation membrane.

[0027] In the third flow path downstream of the pressure reducing pump, another device may be arranged instead of the gas-liquid separation unit (e.g., a cooling / gas-liquid separation unit), or another device may be arranged in addition to the gas-liquid separation unit. Examples of other devices include devices for utilizing carbon dioxide, such as devices for converting carbon dioxide into other compounds. Examples of devices for converting carbon dioxide into other compounds include devices for synthesizing other compounds (e.g., methane gas) using carbon dioxide.

[0028] Examples of each component of the separation device (A) are described below. However, the components of the separation device (A) are not limited to the examples described below. Known components may be used for components other than those characteristic of the separation device (A) according to the present disclosure.

[0029] (Separation section) Examples of the separation section are described below. The separation section includes a separation chamber. The separation chamber is divided into a first space and a second space by a separation membrane. The shapes of the separation membrane, the first space, the second space, and the separation chamber are not particularly limited, as long as they are shapes that can separate carbon dioxide. Examples of the shape of the separation membrane include a sheet shape, a cylindrical shape, a hollow fiber shape, and a spiral shape. The separation device (A) may include multiple separation sections arranged in series and / or in parallel.

[0030] When the separation membrane is in the form of a flat sheet, one of the separation chambers partitioned by the flat sheet-like separation membrane may be used as the first space and the other may be used as the second space. When the separation membrane is in the form of a cylinder, a cylindrical separation membrane may be placed inside the separation chamber, with the inside of the separation membrane used as the first space and the outside used as the second space. Alternatively, a cylindrical separation membrane may be placed inside the separation chamber, with the inside of the cylindrical separation membrane used as the second space and the outside used as the first space.

[0031] The separation membrane can be a membrane that selectively allows carbon dioxide to permeate. Known separation membranes may also be used. Examples of separation membranes used in the separation device (A) include facilitated transport membranes, which increase the carbon dioxide permeation rate due to the presence of water in the membrane. More specifically, the separation membrane used in the separation device (A) can be a membrane that increases the carbon dioxide permeation rate by supplying water vapor to the second space. Therefore, it is important to use a sweep gas containing water vapor as the sweep gas. An example of a separation membrane that increases the carbon dioxide permeation rate by supplying water vapor to the second space is a polymer membrane containing an amine compound (e.g., monoethanolamine, oligoethyleneimine, or alkanolamine). The polymer membrane may also be a composite membrane in which a separation layer containing a polymer is coated on the surface of a porous support membrane. It is preferable for the polymer membrane to contain polymer microparticles that can swell in water, as this prevents membrane defects. It is even more preferable for the separation layer to contain polymer microparticles with acidic functional groups that can further swell by containing amines, as this prevents membrane defects. However, separation membranes other than polymer membranes containing amine compounds may also be used.

[0032] (Steam Generation Source) The steam generation source is not particularly limited, and a known steam generation source may be used. It is preferable to use a steam generation source used in another adjacent facility as the steam generation source. For example, as described below, by using steam generated in a boiler used in the combustion system (S) as a sweep gas, it is possible to eliminate the need to install a new steam generation source. The steam generation source may be a steam generation source that generates saturated or superheated steam at 100°C or higher and 0.1 MPa or higher (1 atmosphere or higher), or may be a steam generation source that generates reduced-pressure steam at 100°C or lower and 0.1 MPa or lower (1 atmosphere or lower). The steam generated by the steam generation source may be at 200°C or higher (e.g., 200°C or higher and 0.6 MPa or higher) or 450°C or lower (e.g., 450°C or lower and 6 MPa or lower). Water for generating steam W is supplied to the steam generation source. As the water vapor generation source for this embodiment, various water vapor generation sources can be used, and it is preferable to use the water vapor generation source of another adjacent facility.

[0033] (Decompression Section) The decompression section is not particularly limited, and any known device capable of decompressing the sweep gas containing water vapor W can be used.

[0034] (Decompression Pump) The decompression pump is not particularly limited, and a known decompression pump can be used. The decompression pump reduces the pressure in the region upstream of the decompression pump (the second space side). For example, the decompression pump may reduce the pressure in the third flow path upstream of the decompression pump to 47 kPa or less (e.g., 20 kPa or less). Setting the pressure to 47 kPa or less makes it easier to separate carbon dioxide from the mixed gas.

[0035] (Other Components) The other components of the separation device (A) (such as the gas-liquid separation section, cooling section, and flow path) are not particularly limited, and known components may be used. The separation device (A) may include components exemplified as components of the combustion system (S). The separation device (A) may include a device for increasing the humidity of the mixed gas flowing into the first space of the separation section. By increasing the humidity of the mixed gas flowing into the first space of the separation section, it is possible to increase the permeation rate of carbon dioxide through the separation membrane.

[0036] (Combustion System) Hereinafter, the combustion system according to this embodiment may be referred to as a "combustion system (S)." The combustion system (S) includes the separation device (A) described above. In the combustion system (S), the steam generation source of the separation device (A) may generate steam W by utilizing thermal energy generated by burning fuel. The mixed gas includes exhaust gas (exhaust gas containing carbon dioxide) generated when burning fuel, and may be the exhaust gas.

[0037] The steam W generated in the steam generation source of the combustion system (S) may be at high temperature and pressure. The combustion system (S) uses a separation device (A), so the high-temperature, high-pressure steam W can be used as a sweep gas.

[0038] As described in the second embodiment, a portion of the steam W generated in the steam generation source of the combustion system (S) may be used for purposes other than the sweep gas. For example, a portion of the steam W may be used to rotate a turbine for generating electricity. The combustion system (S) may or may not include a turbine.

[0039] The form of the steam generation source included in the combustion system (S) is not particularly limited as long as it generates steam W by utilizing thermal energy generated by burning fuel. The steam generation source may include a boiler. The steam generation source may use boiler steam generated in a boiler by burning fuel as the steam W. Alternatively, the steam generation source may generate steam W using boiler steam generated in a boiler by burning fuel as a heat source. In either case, the steam generation source generates steam W by utilizing thermal energy generated by burning fuel.

[0040] The fuel may include at least one selected from the group consisting of fossil fuel, biomass, biogas, and waste, or may be at least one of the fuels. For example, the fuel may include waste or may be waste. Examples of waste include municipal solid waste, sludge, industrial waste, etc. That is, the combustion system (S) may be a waste incineration system (refuse incineration system). By using the combustion system (S) as a waste incineration system, carbon dioxide in the exhaust gas generated by the incineration of waste can be removed.

[0041] Except for the inclusion of the separation device (A), the configuration of the combustion system (S) is not particularly limited, and may include components necessary for a combustion system. These components may be known components. The combustion system (S) may include the components described in embodiment 2.

[0042] Below, examples of embodiments according to the present disclosure will be described in detail with reference to the drawings. The descriptions of the above-described embodiments can be applied to the examples of the embodiments described below, and modifications may be made based on the above-described descriptions. Among the components of the embodiments described below, components that are not essential to the separation device (A) and combustion system (S) according to the present disclosure and can be omitted may be omitted. Furthermore, the matters described below may be applied to the above-described embodiments.

[0043] (Embodiment 1) In Embodiment 1, an example of a separation apparatus (A) will be described. The configuration of a separation apparatus 100 (carbon dioxide separation apparatus 100) of Embodiment 1 is schematically shown in Figure 1. The separation apparatus 100 includes a water vapor generation source 110, a pressure reduction / cooling section 120 (pressure reduction section 121 and cooling section 122), a separation section 130, a pressure reduction pump 140, a pressure gauge 160, a control device 170, a first flow path 181, a second flow path 182, and a third flow path 183.

[0044] The water vapor generating source 110 generates water vapor W to be used as the sweep gas. The separation unit 130 includes a separation membrane 133 that selectively allows carbon dioxide to permeate, and a separation chamber 134. The separation chamber 134 is divided by the separation membrane 133 into a first space 131 and a second space 132. That is, the first space 131 and the second space 132 are adjacent to each other with the separation membrane 133 sandwiched therebetween.

[0045] The first flow path 181 is a flow path that allows the gas to be treated (a mixed gas containing carbon dioxide) to flow through the first space 131. The first flow path 181 includes a first flow path 181a on the upstream side of the first space 131 and a first flow path 181b on the downstream side of the first space 131. If necessary, a pump or the like may be disposed in the first flow path.

[0046] The gas to be treated is introduced into the first space 131 through the first flow path 181a. In the first space 131, at least a portion of the carbon dioxide in the gas to be treated permeates the separation membrane 133 and moves to the second space 132. That is, at least a portion of the carbon dioxide in the gas to be treated is separated in the separation unit 130. The gas to be treated with a reduced carbon dioxide concentration flows through the first flow path 181b. The gas to be treated flowing through the first flow path 181b is treated and / or released depending on the components and application of the gas to be treated.

[0047] The second flow path 182 guides the sweep gas containing water vapor to the second space 132. The third flow path 183 is a flow path through which the carbon dioxide-containing sweep gas generated in the second space 132 flows. The carbon dioxide-containing sweep gas contains water vapor W and carbon dioxide that has permeated the separation membrane 133.

[0048] A pressure reducing pump 140 is disposed in the third flow path 183. A pressure gauge 160 is disposed in the third flow path 183 upstream of the pressure reducing pump 140. The position of the pressure gauge 160 is not limited to the position shown in FIG. 1 , and the pressure gauge 160 may be disposed in another position between the pressure reducing unit 121 and the pressure reducing pump 140.

[0049] The decompression pump 140 reduces the pressure in the passages and spaces upstream of the decompression pump 140. As a result, the sweep gas flows from the steam generation source 110 through the second passage 182, the decompression / cooling section 120, and the second space 132 to the third passage 183. As described above, a gas-liquid separation section (e.g., a cooling / gas-liquid separation section) and / or other devices may be disposed in the third passage 183.

[0050] The separation apparatus 100 may include other instruments and devices as needed. For example, the separation apparatus 100 may include an instrument for monitoring the temperature of the water vapor (sweep gas) present in the second flow path 182. The control device 170 is connected to the instruments and devices within the separation apparatus 100. Note that in FIG. 1, only some of the connections are shown with dotted lines. Also, in FIG. 2 and subsequent figures, the connections between the control device and other instruments and devices are not shown.

[0051] The control device 170 controls the equipment as necessary. For example, the control device 170 controls the pressure reducing unit 121 in accordance with the output from the meter. Specifically, the control device 170 controls the opening degree of the pressure reducing valve included in the pressure reducing unit 121 in accordance with the output from the pressure gauge 160. The control device 170 is not particularly limited, and a control device having a configuration similar to that of a general control device can be used. However, the control device 170 stores a program required to operate the separation device 100, and controls the equipment based on the program.

[0052] In the first embodiment, an example is shown in which the separation apparatus 100 includes a pressure reduction section 121 and a cooling section 122 disposed downstream of the pressure reduction section 121; however, the cooling section 122 may be omitted if possible. As described above, a pressure reduction valve or an orifice may be used for the pressure reduction section 121. A general cooling device may be used for the cooling section 122, and a device that performs cooling using a refrigerant (such as water) may also be used. The water vapor (sweep gas) generated in the water vapor generation source 110 is depressurized and cooled in the pressure reduction section 121 and the cooling section 122 and supplied to the second space 132. Therefore, the water vapor generated in the water vapor generation source 110 can be used regardless of whether it is at a high temperature or high pressure.

[0053] In the first embodiment, the water vapor (sweep gas) generated by the water vapor generation source 110 is supplied to the second space via the pressure reducing section 121 and the cooling section 122. Therefore, the control device 170 can control the pressure reducing section 121 and the cooling section 122 to adjust the flow rate of the water vapor (sweep gas) passing through the pressure reducing section 121 and the cooling section 122 to the minimum required amount. This makes it possible to prevent the energy required for supplying the water vapor from becoming excessive compared to when an excessive amount of water vapor is supplied to the second space 132.

[0054] The separation apparatus 100 may include a cooling section disposed between the separation section 130 and the decompression pump 140. The sweep gas flowing into the second space contains a large amount of water vapor in addition to the carbon dioxide that has permeated the separation membrane. This increases the amount of gas that the decompression pump must suck, leading to increased power consumption. By disposing a cooling section between the separation section 130 and the decompression pump 140, the amount of water vapor contained in the sweep gas can be reduced to the saturated water vapor amount at the cooling temperature in the cooling section. As a result, the capacity and power consumption of the decompression pump can be reduced. Note that the cooling temperature of the sweep gas in the cooling section only needs to be lower than the temperature T of the sweep gas (water vapor-containing gas) supplied to the second space. For example, the sweep gas may be cooled to a temperature in the cooling section in the range of 20 to 60°C.

[0055] 2, the separation apparatus 100 may send water (drain water) generated by condensing water vapor in the sweep gas in the cooling section 122 to the steam generation source 110. The water sent from the cooling section 122 is used as part of the water source for the steam generation source 110. This allows the water (hot water) obtained in the cooling section 122 to be used effectively.

[0056] The separation apparatus 100 may include a gas-liquid separation section disposed in the third flow path 183. Fig. 3 shows an example in which a cooling / gas-liquid separation section 150 including a cooling section and a gas-liquid separation section is disposed in the third flow path 183 downstream of the pressure reduction pump 140. The cooling section in the cooling / gas-liquid separation section 150 is disposed upstream of the gas-liquid separation section in the cooling / gas-liquid separation section 150. The carbon dioxide-containing sweep gas is first cooled in the cooling section of the cooling / gas-liquid separation section 150, and then separated in the gas-liquid separation section into a liquid containing water produced by cooling and a gas containing carbon dioxide.

[0057] As shown in FIG. 3 , the separation apparatus 100 may further include a heat pump 190. Flow paths (not shown) through which a heat medium flows are arranged between the heat pump 190 and the cooling / gas-liquid separation section 150 and between the heat pump 190 and the steam generation source 110. The heat pump 190 recovers thermal energy generated when the carbon dioxide-containing sweep gas is cooled in the cooling / gas-liquid separation section 150. The heat pump 190 supplies the recovered thermal energy to the steam generation source 110. The thermal energy supplied to the steam generation source 110 is used to generate steam. Note that the steam generation source 110 of the separation apparatus 100 of FIG. 3 may use water (hot water) obtained in the cooling section 122 as part of the water source, similar to the separation apparatus 100 shown in FIG. 2 .

[0058] As shown in Fig. 4, the separation device 100 may include a cooling / gas-liquid separation unit 150 disposed in a third flow path 183 between the separation unit 130 and the decompression pump 140, and a cooling / gas-liquid separation unit 150 disposed in the third flow path downstream of the decompression pump 140. The cooling / gas-liquid separation unit 150 may be disposed only in the third flow path 183 between the separation unit 130 and the decompression pump 140. Fig. 4 shows an example in which a heat pump 190 is connected to the cooling / gas-liquid separation unit 150 upstream of the decompression pump 140, but the arrangement of the heat pump 190 is not limited to the arrangement shown in Fig. 4 and may be omitted.

[0059] (Embodiment 2) In Embodiment 2, an example of a combustion system (S) will be described. The configuration of a combustion system 200 of Embodiment 2 is schematically shown in FIG. 5. The combustion system 200 of FIG. 5 includes a separation device (carbon dioxide separation device) 100 and a combustion chamber 210 for combusting fuel. Note that a control device 170a shown in FIG. 5 is a control device that controls the entire combustion system 200, and includes a part that controls the separation device 100. The control device 170a is connected to instruments and devices within the combustion system 200, and controls the devices as needed.

[0060] The steam generation source 110 generates steam by utilizing thermal energy generated by burning fuel in the combustion chamber 210. The combustion chamber 210 can also be considered as part of the steam generation source 110 (the same applies to the following embodiments). The exhaust gas (mixed gas containing carbon dioxide) generated in the combustion chamber 210 flows as the gas to be treated through the first flow path 181a into the first space 131 of the separation unit 130. As described above, at least a portion of the carbon dioxide in the gas to be treated that has flowed into the first space 131 passes through the separation membrane 133 and moves to the second space 132. The steam W generated by the steam generation source 110 flows as a sweep gas through the decompression / cooling unit 120 into the second space 132. The components other than the combustion chamber 210 have been described in the first embodiment, so repeated description will be omitted.

[0061] An example configuration of the combustion system 200 when it is a refuse incineration system (a waste incineration system) is shown schematically in Fig. 6. The combustion system 200 shown in Fig. 6 includes a combustion chamber 210, a separation device 100, an economizer 222, a dust collector 223, a wet smoke scrubber 231, a denitration device 224, a chimney 225, a condensate tank 244, a deaerator 245, and a carbon dioxide storage tank 251. The steam generation source 110 of the separation device 100 shown in Fig. 6 includes a boiler 241.

[0062] The combustion chamber 210 is an incinerator that incinerates waste input from a waste pit (not shown). Exhaust gas (a mixed gas containing carbon dioxide) generated in the combustion chamber 210 flows into the first space 131 of the separation section 130 via the first flow path 181. In the example shown in Figure 6, an economizer 222, a dust collector 223, and a wet smoke scrubber 231 are arranged in this order in the first flow path 181a (the flow path between the combustion chamber 210 and the first space 131). A denitration device 224 and a chimney 225 are arranged in this order in the first flow path 181b downstream of the first space 131.

[0063] The economizer 222 heats water supplied to the boiler 241 by heat exchange with the exhaust gas. The dust collector 223 is a so-called bag filter that collects fly ash contained in the exhaust gas using a filter cloth. The exhaust gas that has passed through the dust collector 223 flows into the wet smoke scrubber 231.

[0064] The wet smoke scrubber 231 is provided with at least one spray section and a packed bed. The spray section sprays a liquid containing a predetermined chemical and water. The chemical is, for example, an alkaline chemical such as caustic soda. The packed bed is filled with a predetermined packing material. The liquid flows into the gaps between the packing materials. Within the wet smoke scrubber 231, the flue gas is sprayed with the liquid and passes through the gaps between the packing materials. By passing through the wet smoke scrubber 231, the temperature of the flue gas is reduced to a predetermined temperature (for example, a temperature in the range of 40°C to 70°C). Furthermore, by passing through the wet smoke scrubber 231, predetermined components contained in the flue gas (such as sulfur oxides and hydrogen chloride) are removed. The flue gas that has passed through the wet smoke scrubber 231 flows into the first space 131 of the separation section 130. The flue gas may contain substances that inhibit carbon dioxide separation in the separation membrane 133. The wet smoke scrubber 231 can remove at least a portion of such inhibitors from the exhaust gas.

[0065] High-humidity exhaust gas flows into the first space 131. Furthermore, a sweep gas containing water vapor W flows into the second space 132. Therefore, a high moisture content state is maintained in the separation membrane 133. Furthermore, since the sweep gas contains substantially no carbon dioxide, the difference between the partial pressure of carbon dioxide in the first space 131 and the partial pressure of carbon dioxide in the second space 132 becomes large. Furthermore, the pressure in the second space 132 is lower than the pressure in the first space 131. These factors promote the separation of carbon dioxide by the separation membrane 133, i.e., the removal of carbon dioxide from the exhaust gas.

[0066] The exhaust gas that has passed through the first space 131 is treated in a denitration device 224 and then released from a chimney 225. The denitration device 224 removes nitrogen oxides and the like from the exhaust gas using a denitration catalyst.

[0067] As described above, the steam generation source 110 includes the boiler 241. The boiler 241 includes a boiler tube group (not shown). The boiler 241 generates high-temperature, high-pressure steam using heat generated in the combustion chamber 210 as a heat source.

[0068] The steam W generated in the boiler 241 is used as a sweep gas. The sweep gas is drawn by the pressure reducing pump 140 and passes through the second flow path 182, the second space 132 (the separation section 130), and the third flow path 183 in this order.

[0069] The high-temperature, high-pressure sweep gas is decompressed and cooled to a predetermined pressure and a predetermined temperature in the decompression / cooling section 120, and then flows into the second space 132. The sweep gas that has flowed into the second space 132 is mixed with carbon dioxide that has permeated the separation membrane 133. As a result, the sweep gas becomes a carbon dioxide-containing sweep gas that contains water vapor W and carbon dioxide, and flows through the third flow path 183.

[0070] The steam W generated in the boiler 241 may be used not only as a sweep gas but also for other purposes. For example, part of the steam W generated in the boiler 241 may be used to rotate a turbine for power generation. For example, the second flow path 182 may be branched between the boiler 241 and the pressure reducing / cooling unit 120, and part of the steam W may be sent to the turbine. In this case, a superheater may be provided in the combustion chamber 210, and the steam to be sent to the turbine may be superheated in the superheater before being sent to the turbine.

[0071] The carbon dioxide-containing sweep gas flows into the cooling and gas-liquid separation section 150. In the cooling and gas-liquid separation section 150, the carbon dioxide-containing sweep gas is cooled, thereby condensing the water vapor contained in the carbon dioxide-containing sweep gas. As a result, in the cooling and gas-liquid separation section 150, the carbon dioxide-containing sweep gas is separated into a gas containing carbon dioxide (substantially carbon dioxide) and a liquid containing water (substantially water). The separated water is sent to the condensate tank 244 and degassed in the deaerator 245. The degassed water is heated by passing through the economizer 222 and then sent to the boiler 241, where it becomes steam W again.

[0072] The carbon dioxide separated in the cooling / gas-liquid separation unit 150 is sent to and stored in the carbon dioxide storage tank 251. As described above, the carbon dioxide separated in the cooling / gas-liquid separation unit 150 may be sent to an apparatus for utilizing carbon dioxide and used therein.

[0073] Since the combustion system 200 includes the pressure reducing / cooling unit 120, high-temperature, high-pressure steam generated in the boiler 241 can be used as the sweep gas. Note that the separation device 100 of the combustion system 200 may be a separation device (A) other than the separation device 100 shown in FIGS. 5 and 6. For example, the separation device described in the first embodiment may be used. Specifically, the separation device 100 shown in FIGS. 2 to 4 may be used.

[0074] As described above, the embodiments and modifications described in Figures 1 to 6 can be combined with each other. Furthermore, unless otherwise specified, the functions and effects described in each embodiment or modification can be similarly exhibited in other embodiments and modifications.

[0075] Examples of carbon dioxide separation devices and combustion systems disclosed above are listed below. (1) A carbon dioxide separation device for separating carbon dioxide from a mixed gas containing carbon dioxide, comprising: a water vapor generation source for generating water vapor to be used for a sweep gas; a separation section including a separation membrane selectively permeable to carbon dioxide and a first space and a second space partitioned by the separation membrane; a first flow path for flowing the mixed gas through the first space; a second flow path for introducing the water vapor-containing sweep gas into the second space; a third flow path for flowing a carbon dioxide-containing sweep gas produced in the second space and containing the water vapor and carbon dioxide; a pressure reduction pump disposed in the third flow path; and a pressure reduction section disposed in the second flow path, wherein the sweep gas is reduced in pressure reduction section and supplied to the second space. (2) The carbon dioxide separation device described in (1), wherein the temperature of the sweep gas supplied to the second space is less than 100°C. (3) The carbon dioxide separation device described in (1) or (2), wherein the pressure reduction section includes a pressure reduction valve. (4) The carbon dioxide separator according to any one of (1) to (3), further including a cooling section disposed in the second flow path downstream of the pressure reduction section. (5) The carbon dioxide separator according to (3), further including a cooling section, wherein the pressure reduction section is disposed downstream of the cooling section. (6) The carbon dioxide separator according to (4), wherein water produced by condensation of the water vapor in the cooling section is used as part of the water source for the water vapor generation source. (7) The carbon dioxide separator according to (5), wherein water produced by condensation of the water vapor in the cooling section is used as part of the water source for the water vapor generation source. (8) The carbon dioxide separator according to any one of (1) to (7), further including a cooling / gas-liquid separation section disposed in the third flow path, which cools the carbon dioxide-containing sweep gas and performs gas-liquid separation. (9) The carbon dioxide separation apparatus according to (8), further comprising a heat pump that recovers thermal energy from the carbon dioxide-containing sweep gas in the cooling / gas-liquid separation section and supplies the recovered thermal energy to the water vapor generation source, wherein the carbon dioxide-containing sweep gas is separated into a gas containing carbon dioxide and a liquid containing water in the cooling / gas-liquid separation section.(10) A combustion system including the carbon dioxide separation device according to any one of (1) to (9), wherein the steam generation source generates the steam by utilizing thermal energy generated by burning a fuel, and the mixed gas includes exhaust gas generated when the fuel is burned. (11) The combustion system according to (10), wherein the steam generation source includes a boiler.

[0076] The present disclosure can be used in a carbon dioxide separation device and a combustion system including the same.

[0077] DESCRIPTION OF SYMBOLS 100: Carbon dioxide separation device 110: Steam generation source 120: Pressure reduction / cooling section 121: Pressure reduction section 122: Cooling section 130: Separation section 131: First space 132: Second space 133: Separation membrane 134: Separation chamber 140: Pressure reduction pump 150: Cooling / gas-liquid separation section 160: Pressure gauge 170, 170a: Control device 181, 181a, 181b: First flow path 182: Second flow path 183: Third flow path 190: Heat pump 200: Combustion system 210: Combustion chamber 241: Boiler

Claims

1. A carbon dioxide separation device for separating carbon dioxide from a mixed gas containing carbon dioxide, comprising: a water vapor generation source for generating water vapor to be used as a sweep gas; a separation section including a separation membrane that is selectively permeable to carbon dioxide and a first space and a second space partitioned by the separation membrane; a first flow path for flowing the mixed gas through the first space; a second flow path for introducing the sweep gas containing the water vapor into the second space; a third flow path for flowing a carbon dioxide-containing sweep gas that is generated in the second space and contains the water vapor and carbon dioxide; a pressure reduction pump disposed in the third flow path; and a pressure reduction section disposed in the second flow path, wherein the sweep gas is reduced in pressure in the pressure reduction section and supplied to the second space.

2. The carbon dioxide separator according to claim 1, wherein the temperature of the sweep gas supplied to the second space is less than 100°C.

3. The carbon dioxide separation device according to claim 1 or 2, wherein the pressure reducing section includes a pressure reducing valve.

4. The carbon dioxide separator according to claim 1 or 2, further comprising a cooling section disposed in the second flow path downstream of the pressure reducing section.

5. The carbon dioxide separation apparatus according to claim 3, further comprising a cooling section, wherein the pressure reducing section is disposed downstream of the cooling section.

6. A carbon dioxide separation device according to claim 4, wherein water produced by condensing the water vapor in the cooling section is used as part of the water source for the water vapor generating source.

7. The carbon dioxide separator according to claim 5, wherein the water generated by condensing the water vapor in the cooling section is used as part of the water source for the water vapor generating source.

8. The carbon dioxide separation device according to claim 1 or 2, further comprising a cooling and gas-liquid separation section disposed in the third flow path for cooling the carbon dioxide-containing sweep gas and separating it into gas and liquid.

9. The carbon dioxide separation device according to claim 8, further comprising a heat pump that recovers thermal energy from the carbon dioxide-containing sweep gas in the cooling / gas-liquid separation section and supplies the recovered thermal energy to the water vapor generation source, wherein the carbon dioxide-containing sweep gas is separated into a gas containing carbon dioxide and a liquid containing water in the cooling / gas-liquid separation section.

10. A combustion system comprising the carbon dioxide separation device according to claim 1 or 2, wherein the steam generation source generates the steam by utilizing thermal energy generated by burning fuel, and the mixed gas includes exhaust gas generated when the fuel is burned.

11. The combustion system of claim 10, wherein the steam generating source comprises a boiler.

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