Carbon dioxide separation and recovery system

Abstract

A carbon dioxide separation and recovery system having: a heat storage unit for storing solar heat and providing heat; a carbon dioxide absorption liquid circulation and regeneration mechanism that uses the heat provided by the heat storage unit to heat an absorption liquid, which absorbs carbon dioxide contained in a gas, causes the absorption liquid to be heated and regenerated, while releasing the carbon dioxide to be separated and recovered, and then causes carbon dioxide contained in the gas to be absorbed again; and a carbon dioxide gas separation and recovery function.

Description

Carbon dioxide separation and recovery system

[0001] This invention relates to a carbon dioxide separation and recovery system.

[0002] Patent Document 1 describes a thermal power generation system equipped with a carbon dioxide separation and recovery device, which includes a boiler that burns fossil fuels, a steam turbine driven by steam generated in the boiler, a condenser that condenses the steam that has driven the steam turbine, a carbon dioxide separation and recovery device that separates and recovers carbon dioxide from the exhaust gas of the boiler, and a solar thermal collector that collects solar heat to generate steam and supplies the steam to the reboiler of the carbon dioxide separation and recovery device. The system is configured such that when the amount of steam generated by the solar thermal collector falls below the amount of steam required by the reboiler, extracted steam is supplied to the reboiler from the steam turbine, and a portion of the drain that has been condensed in the reboiler is recovered in the condenser. Furthermore, when the amount of steam generated by the solar thermal collector exceeds the amount of steam required by the reboiler, the excess steam is recovered in the condenser by bypassing the reboiler.

[0003] Patent No. 5704937

[0004] In order to suppress carbon dioxide emissions resulting from the energy used when separating and recovering carbon dioxide, there are some that use solar thermal energy. For example, in the chemical absorption method, when heating an absorption liquid containing carbon dioxide in a regeneration tower, there are some that use steam generated by solar heat to heat the absorption liquid. In this case, by heating with solar heat that does not emit carbon dioxide, the carbon dioxide emitted from the energy required to separate carbon dioxide is suppressed. However, solar heat cannot be utilized at night or during bad weather when sunlight cannot be received. That is, in any of the carbon dioxide separation and recovery methods such as the chemical absorption method, the physical adsorption method using an adsorbent, and the membrane separation method using a carbon dioxide separation membrane, it is better to be able to stably separate and recover carbon dioxide regardless of day or night and weather conditions, so that the equipment can be stably operated at a high operating rate and the annual separation and recovery amount can be increased. However, if solar heat cannot be stored and utilized, it is impossible to stably continuously operate at a high operating rate regardless of day or night and weather conditions, and the annual separation and recovery amount cannot be increased. Also, similar to the separation and recovery of carbon dioxide, when compressing the separated and recovered carbon dioxide gas and filling it into a high-pressure gas cylinder, liquefying it, or injecting the liquefied carbon dioxide underground for underground storage, a large amount of energy is consumed. Therefore, being able to operate stably regardless of day or night and weather conditions can enhance energy efficiency and the carbon dioxide reduction effect. However, if solar heat cannot be stored and utilized, there is a problem that the separated and recovered carbon dioxide gas cannot be stably made into high-pressure gas or liquefied carbon dioxide at a high operating rate, or cannot be stored underground. The object of the present invention is to suppress the influence of day and night and weather, stably separate and recover carbon dioxide at a high operating rate, make the separated and recovered carbon dioxide into high-pressure gas or liquefied carbon dioxide that is easy to use, or store it underground, thereby increasing the annual carbon dioxide gas separation and recovery amount, the amount of the separated and recovered carbon dioxide gas made into high-pressure gas, the amount of the separated and recovered carbon dioxide gas liquefied, or the amount of the separated and recovered carbon dioxide stored underground.

[0005] The invention described in claim 1 is a carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor driven by the rotational driving force of the turbine; a carbon dioxide absorption liquid circulation and regeneration mechanism that heats an absorption liquid that has absorbed carbon dioxide contained in a gas using the heat provided by the heat storage unit, releasing and separating the carbon dioxide, while regenerating the absorption liquid, and then again absorbing carbon dioxide contained in a gas compressed by the gas compressor; a carbon dioxide gas separation and recovery function; and an injection unit that pressurizes the carbon dioxide separated and recovered by the separation and recovery function into a geological formation using the rotational power of the turbine. The invention described in claim 2 is a carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor driven by the rotational driving force of the turbine; a carbon dioxide adsorbent heating and regeneration mechanism that heats an adsorbent that has adsorbed carbon dioxide contained in a gas using the heat provided by the heat storage unit, releasing and separating the carbon dioxide while regenerating the adsorbent, and then adsorbing carbon dioxide contained in a gas compressed by the gas compressor again; a carbon dioxide gas separation and recovery function; and an injection unit that pressurizes the carbon dioxide separated and recovered by the separation and recovery function into a geological formation using the rotational power of the turbine. The invention described in claim 3 is a carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor and a suction pump driven by the rotation of the turbine; a carbon dioxide separation membrane provided between the gas compressor and the suction pump; and an injection unit that pressurizes the carbon dioxide separated by the separation membrane into the geological formation by the rotational power of the turbine. The invention described in claim 4 is a carbon dioxide separation and recovery system characterized by a gas compressor driven by the rotation of the turbine, and ejecting a high-pressure gas containing carbon dioxide, which has been pressurized by the gas compressor, into the carbon dioxide absorption liquid described in claim 1 in the form of fine bubbles.The invention described in claim 5 is a carbon dioxide separation and recovery system characterized by a gas compressor driven by the rotation of the turbine, and supplying high-pressure gas containing carbon dioxide, which has been pressurized by the gas compressor, into a container containing the carbon dioxide adsorbent described in claim 2. The invention described in claim 6 is a carbon dioxide separation and recovery system characterized by a suction pump driven by the rotation of the turbine, the suction pump being mounted on a carbon dioxide gas separation and recovery piping of a container containing the carbon dioxide adsorbent described in claim 2, and desorption and subsequent suction recovery of carbon dioxide gas while changing the pressure inside the container containing the carbon dioxide adsorbent. The invention described in claim 7 is a carbon dioxide separation and recovery system further comprising a gas pressurizing compressor driven by the rotation of the turbine to pressurize and compress gas, wherein the gas pressurizing compressor further pressurizes and compresses the carbon dioxide gas separated and recovered by any of the methods described in claims 1 to 6 to obtain high-pressure carbon dioxide gas.

[0006] From another perspective, the carbon dioxide separation and recovery system to which the present invention applies comprises a heat storage unit that stores and provides solar heat, a gas compressor or vacuum pump that heats and regenerates a carbon dioxide absorbent liquid or adsorbent material using the heat provided by the heat storage unit, or is operated by the rotational driving force of a turbine driven by the heat provided by the heat storage unit, a separation membrane module that separates carbon dioxide from a gas, and a gas compressor that is driven by the rotation of the turbine to compress the gas supplied to the separation membrane module or the separated and recovered carbon dioxide, or a liquid transfer pump for liquefied carbon dioxide that liquefies and transfers the carbon dioxide.

[0007] According to the present invention, it is possible to stably separate and recover carbon dioxide with a high operating rate while suppressing the effects of day and night and weather, and further increase the amount of carbon dioxide gas separated and recovered annually, whether it is converted into high-pressure gas or liquefied carbon dioxide, which can then be filled into high-pressure gas cylinders or liquefied to make it suitable for transport and use, or compressed and liquefied carbon dioxide gas and injected underground for underground storage.

[0008] This is a diagram showing the overall configuration of the carbon dioxide separation and recovery system according to the first embodiment. This is a diagram showing the overall configuration of the carbon dioxide separation and recovery system according to modification 1 of the first embodiment. This is a diagram showing the overall configuration of the carbon dioxide separation and recovery system according to modification 2 of the first embodiment. This is a diagram showing the overall configuration of the carbon dioxide separation and recovery system according to the second embodiment.

[0009] Embodiments of the present invention will be described in detail below with reference to the attached drawings. [Overall Configuration of Carbon Dioxide Separation and Recovery System] Figure 1 is a diagram showing the overall configuration of the carbon dioxide separation and recovery system 1 according to the first embodiment. The carbon dioxide separation and recovery system 1 recovers carbon dioxide from the atmosphere and stores it by injecting it into the ground. The carbon dioxide separation and recovery system 1 is positioned at a location where carbon dioxide is injected into the ground.

[0010] The carbon dioxide separation and recovery system 1 according to the first embodiment comprises a solar thermal collection unit 10 and a drive unit 20. The carbon dioxide separation and recovery system 1 also comprises a separation unit 30, a liquefaction unit 40 and an injection unit 50.

[0011] The solar thermal collection unit 10 comprises a solar collector 11, a solar collector tube 12, and a heat storage unit 13. The solar collector 11 concentrates sunlight. The solar collector 11 is, for example, a mirror with a parabolic cross-section, and concentrates sunlight at the focal point of the parabola. The solar collector tube 12 receives the sunlight concentrated by the solar collector 11 and heats the heat transfer medium flowing inside the tube. For example, synthetic oil or molten salt can be used as the heat transfer medium. The solar collector tube 12 is positioned at the focal point of the solar collector 11.

[0012] The heat storage unit 13 stores solar heat and provides heat. A heat transfer medium flows inside the heat storage unit 13. Hereinafter, in this specification, the heat transfer medium flowing inside the heat storage unit 13 will be referred to as the heat storage medium. For example, synthetic oil or molten salt can be used as the heat storage medium in the heat storage unit 13. The heat storage unit 13 comprises a high-temperature tank 13a, a low-temperature tank 13b, a heat storage pipe 13c, and a heat exchanger 13d. The high-temperature tank 13a and the low-temperature tank 13b are containers capable of storing the heat storage medium. The heat storage pipe 13c connects the high-temperature tank 13a and the low-temperature tank 13b. The direction in which the heat storage medium flows in the heat storage pipe 13c is controlled by pumps provided in the high-temperature tank 13a and the low-temperature tank 13b, respectively. The heat exchanger 13d is provided in the heat storage pipe 13c between the high-temperature tank 13a and the low-temperature tank 13b. A heat collector tube 12 passes through the heat exchanger 13d. The heat exchanger 13d exchanges heat between the heat storage medium flowing through the heat storage tube 13c and the heat storage medium flowing through the heat collector tube 12.

[0013] The drive unit 20 includes a steam generator 21, a turbine 22, a shaft 23, a steam condenser 24, piping 25, and a circulation pump 26. The steam generator 21, the turbine 22, and the steam condenser 24 are connected by piping 25, and water flows inside piping 25. The circulation pump 26 directs the water inside piping 25 toward the steam generator 21. The water inside piping 25 circulates by flowing in the order of steam generator 21, turbine 22, and steam condenser 24. In the first embodiment, water is used as the medium to rotate the turbine 22, but other mediums may be used to rotate the turbine 22.

[0014] The piping 25 comprises a first branch pipe 251 and a second branch pipe 252. The first branch pipe 251 and the second branch pipe 252 are located between the turbine 22 and the steam condenser 24. The first branch pipe 251 is located closer to the turbine 22 than the second branch pipe 252. The first branch pipe 251 returns to the piping 25 through a heating section 325, which will be described later. The second branch pipe 252 returns to the piping 25 through a heat exchanger 42, which will be described later.

[0015] The steam generator 21 exchanges heat between the water in the piping 25 and the heat transfer medium in the heat collector tube 12, vaporizing the water in the piping 25 and generating steam. The turbine 22 is equipped with blades that rotate when they receive the steam, and a shaft 23 that serves as the axis of rotation for the turbine 22. The shaft 23 transmits the rotational force of the turbine 22 to various devices and serves as a drive source for driving these devices. More specifically, the shaft 23 drives the gas compressor 31, the carbon dioxide compressor 41, and the injection pump 51, which will be described later. The steam condenser 24 changes the state of the steam that has rotated the turbine 22 into a liquid.

[0016] The separation unit 30 separates and recovers carbon dioxide from atmospheric air. The separation unit 30 comprises a gas compressor 31 and a chemical absorption separation unit 32. The gas compressor 31 compresses gas and supplies it to the chemical absorption separation unit 32. The gas compressor 31 is a rotary compressor. The drive unit of the gas compressor 31 is directly connected to the shaft 23 and rotates along with the shaft 23. Alternatively, the shaft 23 and the drive unit of the gas compressor 31 may be connected via a transmission. The transmission is, for example, a device that combines multiple gears with different numbers of teeth. The transmission transmits rotational power to the gas compressor 31 by changing the magnitude of the torque and rotational speed of the rotational power transmitted from the shaft 23. The gas compressor 31 only needs to be able to use the rotational power of the shaft 23 and may be a reciprocating compressor. In this case, the gas compressor 31 converts the rotational power of the shaft 23 into reciprocating motion, causing the piston to reciprocate and compress the gas. In the illustrated example, the gas compressor 31 is supplied with air from the atmosphere, but biogas or combustion exhaust gas may also be supplied.

[0017] The chemical absorption separation unit 32 is a device that separates carbon dioxide by chemical absorption. The chemical absorption separation unit 32 comprises an absorption tower 321, a microbubble supply pipe 322, a regeneration tower 323, a heating unit 325, and absorbent liquid piping 326 and 327. The absorption tower 321 stores an absorbent liquid that absorbs carbon dioxide, and a microbubble supply pipe 322 into which compressed air from a gas compressor 31 is injected is inserted. The absorbent liquid is, for example, an aqueous amine solution. The microbubble supply pipe 322 ejects microbubbles into the absorbent liquid. Here, microbubbles are gases that have been made into fine bubbles so that carbon dioxide can be easily absorbed by the absorbent liquid, for example, nanobubbles with a bubble size of less than 0.001 mm, or microbubbles with a bubble size of 0.001 mm or more and less than 0.1 mm. The regeneration tower 323 recovers carbon dioxide by desorbing it from the absorbent liquid that has absorbed it. The heating section 325 heats the absorbent liquid in the regeneration tower 323. The first branch pipe 251 passes through the heating section 325, and steam that has done work in the turbine 22 is sent through it. This steam heats the absorbent liquid in the regeneration tower 323. The absorbent liquid piping 326 connects the absorption tower 321 and the regeneration tower 323. The absorbent liquid piping 326 is equipped with a liquid transfer pump 326a that transfers the absorbent liquid from the absorption tower 321 to the regeneration tower 323. The absorbent liquid piping 327 connects the absorption tower 321 and the regeneration tower 323. The absorbent liquid piping 327 is equipped with a liquid transfer pump 327a that transfers the absorbent liquid from the regeneration tower 323 to the absorption tower 321. The liquid transfer pumps 326a and 327a are connected to the shaft 23 via a power transmission section (not shown) and operate using the rotational power of the shaft 23. These two liquid transfer pumps, 326a and 327a, are examples of liquid transfer pumps.

[0018] The liquefaction unit 40 liquefies the carbon dioxide gas separated and recovered by the separation unit 30. The liquefaction unit 40 includes a carbon dioxide compressor 41, a heat exchanger 42, and a carbon dioxide cooler 43. The carbon dioxide compressor 41 is a rotary compressor. The drive unit of the carbon dioxide compressor 41 is directly connected to the shaft 23 and rotates along with the shaft 23. Alternatively, the shaft 23 and the drive unit of the carbon dioxide compressor 41 may be connected via a transmission. The carbon dioxide compressor 41 only needs to be able to use the rotational power of the shaft 23 and may be a reciprocating compressor. In this case, the carbon dioxide compressor 41 converts the rotational power of the shaft 23 into reciprocating motion to move a piston back and forth and compress the gas. In the first embodiment, the rotating shaft of the turbine 22 and the rotating shaft of the carbon dioxide compressor 41 are connected coaxially, but the steam generated from the steam generator 21 may be branched and supplied to multiple turbines, allowing the liquid transfer pump and the carbon dioxide compressor to be operated under independent control.

[0019] The heat exchanger 42 is connected to the regenerator 433 (described later) of the carbon dioxide cooler 43 via the second branch pipe 252. The heat exchanger 42 exchanges heat with the absorption solution in the regenerator 433, heating the absorption solution.

[0020] The carbon dioxide cooler 43 is an absorption-type refrigerator that cools carbon dioxide using the heat of vaporization of water as a refrigerant. The carbon dioxide cooler 43 comprises an evaporator 431, an absorber 432, a regenerator 433, and a condenser 434. The evaporator 431, absorber 432, regenerator 433, and condenser 434 are connected by piping. A pipe through which carbon dioxide gas passes is routed through the evaporator 431. Water supplied into the evaporator 431 vaporizes while absorbing heat from the carbon dioxide gas. This cools the carbon dioxide gas and turns it into liquefied carbon dioxide. The absorber 432 absorbs the water vaporized in the evaporator 431 into an absorbent solution (for example, an aqueous lithium bromide solution). The absorber 432 then transports the absorbent solution, whose concentration has decreased after absorbing water, to the regenerator 433. The regenerator 433 uses a heat exchanger 42 to heat the absorbent solution and generate water vapor. The absorbent solution, whose concentration has increased due to the generation of water vapor, is supplied back to the absorber 432. The condenser 434 condenses the water vapor generated by the regenerator 433. The water liquefied by the condenser 434 is supplied back to the evaporator 431.

[0021] The injection unit 50 includes an injection pump 51 and an injection well 52. The injection pump 51 adds energy to the liquefied, separated carbon dioxide to inject carbon dioxide into the geological formation. The injection pump 51 is, for example, a positive displacement pump. The drive unit of the injection pump 51 is directly connected to the shaft 23 and rotates along with the shaft 23. Alternatively, the shaft 23 and the drive unit of the injection pump 51 may be connected via a transmission. The injection pump 51 only needs to be able to use the rotational power of the shaft 23. The injection pump 51 may impart energy to the liquid by rotational motion or by reciprocating motion. When imparting energy to the liquid by reciprocating motion, the injection pump 51 converts the rotational power of the shaft 23 into reciprocating motion to cause a piston to reciprocate. The injection pump 51 is an example of a liquid transfer pump.

[0022] The injection well 52 is a pipe that extends underground, reaching deep into bedrock or geological formations that do not allow carbon dioxide to pass through. The injection well 52 may extend, for example, to an oil reservoir or a natural gas reservoir, and the separated and recovered carbon dioxide may be injected into the cavity left after the oil or natural gas has been pumped out. The injection pump 51 is connected to the shaft 23. The injection pump 51 is driven by the rotation of the shaft 23. The injection pump 51 pressurizes liquefied carbon dioxide and injects it into the ground via the injection well 52 for storage.

[0023] [Operation for separating and recovering carbon dioxide] First, air from the atmosphere is supplied to the gas compressor 31 of the separation unit 30. The gas compressor 31 compresses the supplied air and supplies the compressed air to the chemical absorption separation unit 32. The chemical absorption separation unit 32 supplies the supplied air into the absorption tower 321 via the microbubble supply pipe 322. A portion of the carbon dioxide in the air supplied into the absorption tower 321 is absorbed by the absorbent liquid. Hereinafter, the absorbent liquid that has absorbed carbon dioxide may be referred to as the rich absorbent liquid. The absorption tower 321 releases air with a reduced carbon dioxide concentration into the atmosphere.

[0024] The absorption tower 321 supplies the rich absorbent to the regeneration tower 323. In the regeneration tower 323, the rich absorbent is heated to separate the absorbent from carbon dioxide. The separated carbon dioxide is then supplied to the liquefaction unit 40. The regenerated absorbent is then supplied back to the absorption tower 321 for circulation. The chemical absorption separation unit 32 is an example of a circulation and regeneration mechanism for carbon dioxide absorbent. The chemical absorption separation unit 32 is also an example of a carbon dioxide gas separation and recovery function. However, even if the absorbent has been heated and regenerated, if the temperature of the absorbent is high, the absorption performance when absorbing carbon dioxide again will decrease. Therefore, a cooler may be provided to cool the regenerated absorbent. For example, cold energy may be generated in the carbon dioxide cooler 43, and this cold energy may be used to cool the regenerated absorbent.

[0025] The carbon dioxide gas supplied to the liquefaction unit 40 is compressed by the carbon dioxide compressor 41 to a pressure greater than the pressure at the triple point of carbon dioxide. The compressed carbon dioxide gas is then cooled and liquefied by the carbon dioxide cooler 43 while maintaining its pressure.

[0026] The liquefied carbon dioxide is transported to the injection section 50. The liquefied carbon dioxide transported to the injection section 50 is then pumped into the injection well 52 by the injection pump 51 of the injection section 50. The liquefied carbon dioxide is injected into the underground geological formation to which the injection well 52 is connected and stored underground.

[0027] [Operation of the heat storage unit] The heat storage unit 13 stores excess solar heat generated when the amount of heat required for steam generation in the steam generator 21 exceeds the amount of heat required for steam generation during the period when sunlight is irradiating the solar collector 11. The heat storage unit 13 also supplies the stored heat to the drive unit 20 during the period when sunlight is not irradiating the solar collector 11. The period when sunlight is irradiating the solar collector 11 is, for example, a sunny day when sunlight is shining on the ground. The period when sunlight is not irradiating the solar collector 11 is, for example, the night after sunset until sunrise the next day, or a period when the weather is cloudy or rainy.

[0028] When the heat storage unit 13 performs heat storage, the heat storage medium contained in the low-temperature tank 13b is moved to the high-temperature tank 13a. At this time, the heat storage medium passes through the heat exchanger 13d, which is provided between the low-temperature tank 13b and the high-temperature tank 13a. In the heat exchanger 13d, the heat storage medium is heated by exchanging heat with the heat medium in the heat collecting tube 12. The heated, high-temperature heat storage medium is then flowed into the high-temperature tank 13a for storage.

[0029] Furthermore, the heat storage unit 13 supplies the heat it stores to the water circulating in the drive unit 20 during periods when solar heat is not supplied to the solar collector 11. More specifically, the heat storage unit 13 flows the heat storage medium from the high-temperature tank 13a to the low-temperature tank 13b, and the heat exchanger 13d exchanges heat with the heat medium in the solar collector tube 12. The heat medium in the solar collector tube 12 is heated by the heat storage medium and becomes hot. The heat medium in the solar collector tube 12 flows to the steam generator 21 and heats the water in the piping 25. The water in the piping 25 is heated by the heat medium in the solar collector tube 12 and becomes steam, which rotates the turbine 22. In other words, the turbine 22 is driven by the heat provided by the heat storage unit 13. As the turbine 22 rotates, the shaft 23 rotates, and various devices that use the shaft 23 as a driving source are driven. More specifically, the gas compressor 31, the carbon dioxide compressor 41, and the injection pump 51 are rotated. In other words, the gas compressor 31 is driven by the rotation of the turbine 22. The carbon dioxide compressor 41 is also driven by the rotation of the turbine 22. The injection pump 51 is also driven by the rotation of the turbine 22.

[0030] Furthermore, the heat supplied from the heat storage unit 13 is supplied to the heating unit 325 via the first branch pipe 251. The heating unit 325 heats the absorbent liquid, separating and recovering carbon dioxide. In addition, the heat supplied from the heat storage unit 13 is supplied to the heat exchanger 42 via the second branch pipe 252. The carbon dioxide cooler 43 uses the heat exchanger 42 to cool and liquefy the carbon dioxide gas.

[0031] With this configuration, the carbon dioxide separation and recovery system 1 according to the first embodiment can utilize solar heat to separate and recover carbon dioxide and inject and store it underground with a high operating rate, not only at night, during sunset and sunrise, but also during daytime hours, including rainy or cloudy days.

[0032] Furthermore, when the amount of solar heat collected by the solar collector 11 exceeds the amount of steam generated by the steam generator 21 necessary for the operation of the carbon dioxide separation and recovery system 1, and the excess solar heat is collected and stored in the heat storage unit 13, it is desirable that, as a method of circulating the heat transfer medium in the solar collector tube 12, the excess heat is stored in the heat storage unit 13 via a circulation path that passes through the solar collector 11 and the heat exchanger 13d, in addition to the circulation path that passes through the solar collector 11 and the steam generator 21. To achieve this, the on / off valves provided on the branched flow paths of the upstream and downstream sections of the heat exchanger 13d are controlled, and during periods when excess heat is generated, the valves on the upstream and downstream circulation paths of the heat exchanger 13d, which were closed during periods when excess heat was not generated, are opened, allowing the heat transfer medium to circulate in both the circulation path that passes through the steam generator 21 and the circulation path that passes through the heat exchanger 13d. This allows the excess solar heat to be stored in the heat storage unit 13 while the carbon dioxide separation and recovery system 1 is in operation.

[0033] Furthermore, when supplying the heat stored in the heat storage unit 13 to the water circulating in the drive unit 20 during periods when solar heat is not supplied to the solar collector 11, it is preferable to control the on / off valves provided on the branched flow paths of the upstream and downstream parts of the heat exchanger 13d. During periods when solar heat is not supplied to the solar collector 11, the valve in the circulation path passing through the solar collector 11 is closed, and only the valve that forms a circulation path passing through the heat exchanger 13d and the steam generator 21 is opened. This selectively allows the heat stored in the heat storage unit 13 to circulate only through the circulation path passing through the steam generator 21, thereby efficiently utilizing the heat stored in the heat storage unit 13 for steam generation.

[0034] Furthermore, in the carbon dioxide separation and recovery system 1, the rotational force of the shaft 23 is used to drive the gas compressor 31, the carbon dioxide compressor 41, and the injection pump 51. However, the shaft 23 does not necessarily need to drive all three of the gas compressor 31, the carbon dioxide compressor 41, and the injection pump 51; it may drive only one of them. Also, the second branch pipe 252 is located downstream of the first branch pipe 251 in the direction in which water flows through the piping 25, but it may also be located upstream of the first branch pipe 251.

[0035] [Modification 1 of the First Embodiment] Figure 2 shows the overall configuration of the carbon dioxide separation and recovery system 2 according to Modification 1 of the First Embodiment. Modification 1 of the First Embodiment differs from the First Embodiment in that the chemical absorption separation unit 32 of the separation unit 30 is replaced with a physical adsorption separation unit 34. The same reference numerals are used for functions similar to those in the First Embodiment, and their explanation is omitted here.

[0036] The carbon dioxide separation and recovery system 2 comprises a solar thermal collection unit 10, a drive unit 20, a separation unit 230, a liquefaction unit 40, and an injection unit 50. The separation unit 230 comprises a gas compressor 31 and a physical adsorption separation unit 34. The physical adsorption separation unit 34 comprises an adsorption tank 341, a heat exchanger 342, and a suction pump 343.

[0037] The adsorption tank 341 stores an adsorbent material that adsorbs carbon dioxide inside the tank. Examples of adsorbents include zeolite and activated carbon. The adsorption tank 341 is also equipped with an openable and closable outlet 341a. The outlet 341a is used to replace the gas inside the adsorption tank 341. The heat exchanger 342 heats the inside of the adsorption tank 341. Steam that has done work in the turbine 22 is sent to the heat exchanger 342 via the first branch pipe 251. The heat from this steam heats the inside of the adsorption tank 341. The suction pump 343 reduces the pressure inside the adsorption tank 341. The suction pump 343 includes a gear 343a provided on the shaft 23 to obtain rotational power for the shaft 23, and a rotating shaft 343b that transmits the rotational power of the gear 343a to the suction pump 343. The rotating shaft 343b is connected to the drive unit of the suction pump 343, and the suction pump 343 is driven by the rotational power of the rotating shaft 343b.

[0038] [Operation for separating and recovering carbon dioxide] In the physical adsorption method, carbon dioxide is separated from other gases using a pressure difference or temperature difference. Specifically, first, the outlet 341a of the adsorption tank 341 is closed and the gas compressor 31 is driven. Compressed air from the gas compressor 31 is supplied to the adsorption tank 341, increasing the pressure inside the adsorption tank 341. When the pressure inside the adsorption tank 341 increases, the adsorbent material adsorbs carbon dioxide. Next, the outlet 341a is opened and the gas with a low concentration of carbon dioxide is discharged. Then, after closing the outlet 341a, the suction pump 343 is driven to reduce the pressure inside the adsorption tank 341. When the pressure inside the adsorption tank 341 decreases, carbon dioxide is desorbed from the adsorbent material. Then, the desorbed carbon dioxide is recovered.

[0039] Furthermore, adsorbents generally have a higher adsorption rate at low temperatures and a lower adsorption rate at high temperatures. Therefore, the adsorption tank 341 may be heated when desorbing carbon dioxide from the adsorbent. Heating the adsorbent allows more carbon dioxide to be desorbed, so compared to not heating the adsorbent, more carbon dioxide can be adsorbed when the adsorbent is reused. Heating the adsorption tank 341 is performed by supplying steam to the heat exchanger 342 via the first branch pipe 251. Alternatively, the adsorption tank 341 may be cooled when adsorbing carbon dioxide onto the adsorbent. For example, cold energy may be generated using a carbon dioxide cooler 43 and supplied to the adsorption tank 341. The physical adsorption separation unit 34 is an example of a heating and regeneration mechanism for carbon dioxide adsorbent and an example of a carbon dioxide gas separation and recovery function.

[0040] Thus, in this modified example 1 of the first embodiment, carbon dioxide can be separated by changing the pressure inside the adsorption tank 341 using a gas compressor 31 driven by heat supplied from the heat storage unit 13 and a suction pump 343. Furthermore, carbon dioxide can be efficiently separated by changing the temperature inside the adsorption tank 341 using the heat supplied from the heat storage unit 13.

[0041] In Modification 1 of the First Embodiment, carbon dioxide was separated using both pressure changes and temperature changes in the adsorption tank 341. However, carbon dioxide may also be separated using only one of the pressure changes or temperature changes in the adsorption tank 341.

[0042] [Modification 2 of the First Embodiment] Figure 3 shows the overall configuration of the carbon dioxide separation and recovery system 3 according to Modification 2 of the First Embodiment. In Modification 2 of the First Embodiment, the difference from the First Embodiment is that the chemical absorption separation unit 32 is replaced with a separation membrane module 36. The same reference numerals are used for the same functions as in the First Embodiment, and their explanation is omitted here.

[0043] The carbon dioxide separation and recovery system 2 comprises a solar thermal collection unit 10, a drive unit 20, a separation unit 330, a liquefaction unit 40, and an injection unit 50. The separation unit 330 comprises a gas compressor 31 and a separation membrane module 36.

[0044] The separation membrane module 36 includes a separation membrane 361 and a suction pump 362. The separation membrane 361 selectively allows carbon dioxide to pass through. The separation membrane 361 is disposed inside the tube of the tubular separation membrane module 36, dividing the inside of the tube into an upstream side and a downstream side. The suction pump 362 is provided on the downstream side of the separation membrane 361, reducing the air pressure on the downstream side inside the separation membrane module 36. The suction pump 362 includes a gear 362a provided on the shaft 23 to obtain the rotational power of the shaft 23, and a rotating shaft 362b that transmits the rotational power of the gear 362a to the suction pump 362. The rotating shaft 362b is connected to the drive unit of the suction pump 362, and the suction pump 362 is driven by the rotational power of the rotating shaft 362b. Examples of the suction pump 362 include a vacuum pump and a vacuum reducing pump.

[0045] [Operation of Separating and Recovering Carbon Dioxide] First, air in the atmosphere is supplied to the gas compressor 31 of the separation unit 30. The gas compressor 31 compresses the supplied air to make the air pressure higher than the atmospheric pressure. The magnitude of the pressure of the air compressed by the gas compressor 31 is appropriately set according to the performance of the separation membrane and the like. Also, the suction pump 362 is driven to reduce the pressure on the downstream side of the separation membrane 361. As a result, a pressure difference occurs between the upstream side and the downstream side of the separation membrane 361, and the carbon dioxide gas passes through the separation membrane and moves to the downstream side. The carbon dioxide that has moved to the downstream side is recovered and supplied to the liquefaction unit 40. On the other hand, the air remaining on the upstream side of the separation membrane 361 with a lower concentration of carbon dioxide is discharged into the atmosphere.

[0046] [Second Embodiment] FIG. 4 is a diagram showing the overall configuration of the carbon dioxide separation and recovery system 4 according to the second embodiment. In the second embodiment, compared with the modified example 2 of the first embodiment, it further differs in that it includes a renewable energy power generation unit 60. Also, the liquefaction unit 240 of the second embodiment differs from the liquefaction unit 40 of the first embodiment in that the carbon dioxide cooler 43 has become a turbo refrigerator 73. Note that the same reference numerals are used for the same functions as in the first embodiment, and the description thereof is omitted here.

[0047] The renewable energy power generation unit 60 can exemplify, for example, solar power generation, solar thermal power generation, wind power generation, geothermal power generation, and hydroelectric power generation. In the second embodiment, solar power generation will be described as an example. The renewable energy power generation unit 60 may be provided with power transmission facilities to the outside and supply power to the outside, or may supply power only to the carbon dioxide separation and recovery system 4.

[0048] The renewable energy power generation unit 60 includes a solar power generation device 61 and a power storage unit 62. The solar power generation device 61 can use solar cells that generate electricity when irradiated with sunlight. The type of solar cell is not particularly limited. For example, silicon-based solar cells and compound-based solar cells can be cited as an example. The power generated by the solar power generation device 61 is supplied to various devices of the carbon dioxide separation and recovery system 4. The power storage unit 62 is a device that can be charged and discharged. For example, a storage battery is used. The power storage unit 62 stores a part of the power generated by the solar power generation device 61. The power storage unit 62 supplies the stored power to various devices of the carbon dioxide separation and recovery system 4.

[0049] The liquefaction unit 240 includes a carbon dioxide compressor 41 and a turbo refrigerator 73. The turbo refrigerator 73 has a compressor inside, compresses the refrigerant using the compressor, and executes a refrigeration cycle. The carbon dioxide gas cooled by this turbo refrigerator 73 is liquefied into liquefied carbon dioxide. In the second embodiment, the compressor of this turbo refrigerator 73 is driven by the power supplied by the renewable energy power generation unit 60. During periods when sunlight is not irradiated, such as at night, the power storage unit 62 supplies power to the turbo refrigerator 73.

[0050] In the carbon dioxide separation and recovery system 4 according to the second embodiment, for example, even in a place where no power transmission line is drawn, such as a desert, carbon dioxide in the atmosphere can be separated and recovered from the air around the system on-site and stored underground.

[0051] [Other] In this embodiment, an absorption chiller was used as the carbon dioxide cooler 43, but an adsorption chiller may also be used. In this embodiment, carbon dioxide is separated and recovered from the atmosphere, but for example, carbon dioxide may be separated from biogas discharged from a biomass fermentation tank. Also, the arrangement of the mirrors for collecting solar heat is not particularly limited. For example, a large number of flat mirrors may be arranged on the ground to surround the tower with respect to the solar collector 11 attached to the top of the tower. In this embodiment, liquefied carbon dioxide was stored in the geological formation using a pressurized pump 51, but liquefied carbon dioxide may also be used as a raw material gas for commercial and industrial purposes. In this case, the pressurized pump 51 may be used to fill carbon dioxide cylinders with high-pressure carbon dioxide gas, or to fill tank trucks, etc. with liquefied carbon dioxide. Also, the recovered carbon dioxide may be solidified and used as dry ice.

[0052] 1, 2, 3, 4...Carbon dioxide separation and recovery system, 10...Solar thermal collection unit, 11...Collector, 12...Collector tube, 13...Heat storage unit, 13a...High-temperature tank, 13b...Low-temperature tank, 13c...Heat storage tube, 13d...Heat exchanger, 20...Drive unit, 21...Steam generator, 22...Turbine, 23...Shaft, 24...Steam condenser, 25...Piping, 30...Separation unit, 31...Gas compressor, 32...Chemical absorption separation unit, 34...Physical adsorption separation unit, 36...Separation membrane module, 40...Liquefaction unit, 41...Carbon dioxide compressor, 42...Heat exchanger, 43...Carbon dioxide cooler, 50...Injection unit, 51...Injection pump, 52...Injection Well, 60...Renewable energy generation section, 61...Solar power generation equipment, 62...Energy storage section, 73...Turbo chiller, 230...Separation section, 240...Liquefaction section, 251...First branch pipe, 252...Second branch pipe, 321...Absorption tower, 322...Microbubble supply pipe, 323...Regeneration tower, 325...Heating section, 326a, 326b...Liquid transfer pump, 330...Separation section, 341...Adsorption tank, 341a...Discharge port, 342...Heat exchanger, 343...Suction pump, 344...Shaft, 346b...Rotating shaft, 361...Separation membrane, 362...Suction pump, 362a...Gear, 431...Evaporator, 432...Absorber, 433...Regenerator, 434...Condenser

Claims

1. A carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor driven by the rotational driving force of the turbine; a carbon dioxide absorption liquid circulation and regeneration mechanism that heats an absorption liquid containing carbon dioxide contained in a gas using the heat provided by the heat storage unit, releasing and separating the carbon dioxide, while regenerating the absorption liquid, and then again absorbing carbon dioxide contained in a gas compressed by the gas compressor; a carbon dioxide gas separation and recovery function; and an injection unit that pressurizes the carbon dioxide separated and recovered by the separation and recovery function into a geological formation using the rotational power of the turbine.

2. A carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor driven by the rotational driving force of the turbine; a carbon dioxide adsorbent heating and regeneration mechanism that heats an adsorbent that has adsorbed carbon dioxide contained in a gas using the heat provided by the heat storage unit, releasing and separating the carbon dioxide while regenerating the adsorbent, and then adsorbing carbon dioxide contained in a gas compressed by the gas compressor again; a carbon dioxide gas separation and recovery function; and an injection unit that pressurizes the carbon dioxide separated and recovered by the separation and recovery function into a geological formation using the rotational power of the turbine.

3. A carbon dioxide separation and recovery system comprising: a heat storage unit that stores and provides solar heat; a turbine driven by the heat provided by the heat storage unit; a gas compressor and a suction pump driven by the rotation of the turbine; a carbon dioxide separation membrane provided between the gas compressor and the suction pump; and an injection unit that pressurizes the carbon dioxide separated by the separation membrane into a geological formation using the rotational power of the turbine.

4. A carbon dioxide separation and recovery system characterized by a gas compressor driven by the rotation of the turbine, and ejecting a high-pressure gas containing carbon dioxide, which has been pressurized by the gas compressor, into the carbon dioxide absorption liquid described in claim 1 in the form of fine bubbles.

5. A carbon dioxide separation and recovery system characterized by a gas compressor driven by the rotation of the turbine, and supplying a high-pressure gas containing carbon dioxide, which has been pressurized by the gas compressor, into a container containing the carbon dioxide adsorbent described in claim 2.

6. A carbon dioxide separation and recovery system characterized by comprising a suction pump driven by the rotation of the turbine, and the suction pump being mounted on a carbon dioxide gas separation and recovery piping of a container containing the carbon dioxide adsorbent described in claim 2, wherein carbon dioxide gas is desorbed and then recovered by suction while the pressure inside the container containing the carbon dioxide adsorbent is changed.

7. A carbon dioxide separation and recovery system further comprising a gas pressurizing compressor driven by the rotation of the turbine to pressurize and compress the gas, wherein the gas pressurizing compressor further pressurizes and compresses the carbon dioxide gas separated and recovered by any of the methods described in claims 1 to 6 to obtain high-pressure carbon dioxide gas.

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