Apparatus for recovering carbon dioxide and method for recovering carbon dioxide

Abstract

To provide an apparatus for recovering carbon dioxide which recovers carbon dioxide in liquid while further reducing a load of a vacuum pump.SOLUTION: Means of solving the problem is an apparatus for recovering carbon dioxide including: a storage unit that is constituted by a partition wall that separates an internal space from the atmosphere, and stores liquid in which carbon dioxide is dissolved in the internal space; a suction unit that raises the liquid by sucking gas present in the internal space; an adjuster that adjusts distance in a vertical direction between a water supply surface of the liquid facing the atmosphere and a water surface formed in the internal space by the stored liquid; and an accumulation unit that accumulates the carbon dioxide recovered from the internal space.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide recovery device. [Background technology]

[0002] As a measure against global warming, there is a worldwide demand to reduce the burden on the global environment by reducing the amount of carbon dioxide in the atmosphere. To achieve this, two things are necessary: ​​reducing carbon dioxide emissions and, at the same time, reducing the concentration of carbon dioxide in the atmosphere by capturing carbon dioxide that is already present in the atmosphere. The concentration of carbon dioxide in the atmosphere is low, at around 400 ppm, so in order to reduce the concentration of carbon dioxide in the atmosphere, a method that minimizes the release of new carbon dioxide as energy for capture is required.

[0003] One method of capturing carbon dioxide without releasing new carbon dioxide is to capture it through seawater or freshwater, which contains dissolved carbon dioxide from the atmosphere, and a known method is to extract carbon dioxide from the aforementioned seawater or freshwater by reducing the pressure.

[0004] Patent Document 1 describes a carbon dioxide recovery system that depressurizes a regeneration tank installed in a seawater circulation line with one end immersed in seawater, and separates carbon dioxide dissolved in the seawater. Specifically, the system separates carbon dioxide bubbles in a decompressed space to remove carbon dioxide from seawater, and recovers the carbon dioxide.

[0005] However, because the device described in Patent Document 1 circulates seawater and reduces its pressure to pump it up, the water level in the regeneration tank fluctuates in response to tidal changes. The magnitude of tidal changes varies by region, but for example, along the Pacific coast of Japan, there is a tidal difference of about 2 meters, and in the Ariake Sea, there is a tidal difference of about 6 meters. For this reason, the regeneration tank needs to be large in height to accommodate tidal changes, and as the regeneration tank becomes larger, the load on the vacuum pump increases. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2023-048054 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a carbon dioxide recovery device that recovers carbon dioxide from a liquid while further reducing the load on a vacuum pump. [Means for solving the problem]

[0008] In order to solve the above problems, a carbon dioxide recovery device according to one aspect of the present invention includes a storage section that is composed of a partition wall that separates the atmosphere from an internal space and that stores a liquid in which carbon dioxide is dissolved in the internal space; a suction unit that lifts the liquid by sucking gas present in the internal space; The device is characterized by having an adjuster that adjusts the vertical distance between the water supply surface of the liquid facing the atmosphere and the water surface formed in the internal space by the stored liquid, and a storage section that stores carbon dioxide recovered from the internal space. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a carbon dioxide recovery device that recovers carbon dioxide from a liquid while further reducing the load on a vacuum pump. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a carbon dioxide recovery device according to a first embodiment of the present invention. [Figure 2] 1A and 1B are schematic diagrams showing the relationship between pressure and pumping height according to the first embodiment of the present invention, and schematic diagrams showing the relationship between the amount of dissolved CO2 and decompression time when the pressure of an aqueous carbon dioxide solution is reduced. [Figure 3] FIG. 5 is a schematic diagram of a carbon dioxide recovery device according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram of a carbon dioxide recovery device according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a schematic diagram of a carbon dioxide recovery device according to a fourth embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram of a carbon dioxide recovery device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] One example of the present invention is a carbon dioxide recovery device that is composed of a partition wall that separates the atmosphere from an internal space and includes a storage section that stores a liquid in which carbon dioxide is dissolved in the internal space, and a suction section that lifts the liquid by sucking gas present in the internal space. It also includes an adjuster that adjusts the vertical distance between a water supply surface of the liquid facing the atmosphere and a water surface formed in the internal space by the stored liquid, and a storage section that accumulates carbon dioxide recovered from the internal space. The present invention will be described in detail below with reference to the drawings.

[0012] A carbon dioxide capture device according to one embodiment of the present invention captures carbon dioxide from the atmosphere by reducing the pressure of a liquid containing dissolved carbon dioxide, such as rainwater, river water, lake water, or seawater, using a vacuum pump to capture the carbon dioxide dissolved in the liquid. In freshwater such as rainwater or river water, atmospheric carbon dioxide is dissolved at equilibrium pressure. Seawater, by comparison, has an even higher solubility of carbon dioxide. Furthermore, the solubility of carbon dioxide in water is high at low temperatures and low at high temperatures. Furthermore, the higher the atmospheric pressure, the higher the solubility of carbon dioxide, and the lower the atmospheric pressure, the lower the solubility.

[0013] In order to reduce the amount of carbon dioxide in the atmosphere as a measure against global warming, it is necessary to extract carbon dioxide while feeding and discharging large amounts of seawater or freshwater into the device. In order to capture carbon dioxide from seawater or freshwater using low energy, it is desirable to extract carbon dioxide by depressurizing the seawater or freshwater.

[0014] The carbon dioxide capture device according to the present invention can capture carbon dioxide at low cost with a simple device configuration. Specifically, seawater or freshwater is pumped, the carbon dioxide released from the storage section is captured, and the seawater or freshwater is circulated within the device using the siphon principle. Here, for example, the storage section is a Torricelli vacuum (a vacuum space created at the top as water is pumped), and a Torricelli vacuum refers to a vacuum space created in a space above the height limit at which water can be pumped by reducing pressure. It is generally known that a Torricelli vacuum is formed due to the relationship between atmospheric pressure, the specific gravity of the solution, and the vapor pressure of the solution; for water at sea level, a Torricelli vacuum occurs when the depth exceeds approximately 10 meters.

[0015] In one embodiment of the carbon dioxide capture device of the present invention, carbon dioxide dissolved in seawater or freshwater is released as a gas when a Torricelli vacuum is applied, so that the carbon dioxide can be discharged using a vacuum pump and captured in a capture tank. The carbon dioxide capture device of the present invention also utilizes, for example, the siphon principle to circulate the pumped seawater or freshwater within the device under reduced pressure. The method of circulation within the device is not limited to the siphon principle, and any other known technology may be used as long as it is a mechanism for circulating a liquid.

[0016] In the carbon dioxide recovery device of the present invention, the pressure density due to the weight of the liquid in the water supply channel and the pressure density of the liquid in the drainage channel are the same if the water supply channel and the drainage channel are at the same height. In other words, if the water level of the water supply surface is higher than the water level of the drainage surface, the liquid can be made to flow from the water supply side to the drainage side by potential energy without power assistance such as a water flow pump. Furthermore, even if the water supply surface and the drainage surface are at the same height, the liquid can be circulated within the device by providing slight power assistance with a water flow pump.

[0017] By adopting the above-described configuration and method, the carbon dioxide capture device of the present invention enables carbon dioxide capture with low energy in a carbon dioxide capture device. Furthermore, the present invention further reduces fluctuations between the height position of the storage unit and the liquid level within the storage unit, which occur due to fluctuations in sea level caused by tidal forces or fluctuations in the water level of freshwater such as river water or lake water due to rising water levels, thereby enabling the storage unit to be made smaller. The tidal range of seawater caused by tidal forces varies by region. For example, the tidal range is approximately 2 meters along the Pacific coast and 6 meters in the Ariake Sea. Therefore, the storage unit must be large enough in height to accommodate fluctuations in sea level. By providing an adjuster that adjusts the vertical distance between the sea level and the liquid, the storage unit can be made smaller, reducing the load on the vacuum pump.

[0018] That is, the carbon dioxide capture device of the present invention is composed of a partition wall that separates the atmosphere from an internal space, and is provided with a storage section that stores a liquid in which carbon dioxide is dissolved in the internal space. Furthermore, the device further includes an adjuster that adjusts the vertical distance between the liquid outside the storage section and the liquid inside the storage section, and a storage section that captures and stores the carbon dioxide released from the liquid. By adopting such a configuration, the device is characterized by being able to capture carbon dioxide at low cost.

[0019] The present invention will be described in detail below with reference to preferred embodiments. However, the present invention is not limited to the following embodiments, and appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of those skilled in the art are also included within the scope of the present invention, provided that they do not deviate from the spirit of the present invention.

[0020] [First embodiment] An example of the functional configuration of a carbon dioxide recovery device will be described below with reference to FIG.

[0021] The pressure inside the CO2 release tank (storage) 101 is reduced by a vacuum pump 102, and liquid 100, which is seawater with dissolved carbon dioxide from the atmosphere, is pumped into the CO2 release tank (storage) 101 via a pumping pipe 107 equipped with a water inlet. The pressure inside the CO2 release tank (storage) 101 is set to approximately 2 kPa, and the Torricelli vacuum height Ht between the liquid level of the liquid 100 inside the CO2 release tank (storage) 101 and the seawater level at low tide is set to approximately 10 m. When a small amount of liquid 100 is pumped by a pumping pump 109, the liquid 100 inside the CO2 release tank (storage) 101 is drained by its own weight through a drain pipe 108 and a drain outlet 110 so that the Torricelli vacuum height Ht is maintained. In other words, the liquid 100 is circulated using little energy using the siphon principle.

[0022] A decompressed space 111 is formed inside the CO2 release tank (storage section) 101, and the carbon dioxide dissolved in the liquid 100 is released into the space 111. The released carbon dioxide has water vapor removed by a water vapor filter 103, and is collected in a CO2 buffer tank 104 via a vacuum pump 102, and is then stored in a CO2 storage section (accumulation section) 106 by a compressor 105.

[0023] As the tide level of seawater fluctuates due to tidal forces, the vacuum level in space 111 is controlled in accordance with the rise and fall of the tide level. The difference in tide level varies depending on the region; for example, along the Pacific coast of Japan, the difference in tide level is about 2 m. For this reason, the vacuum level in space 111 is reduced to lower the Torricelli vacuum height Ht, thereby controlling the position height of the liquid 100 inside the CO2 release tank (storage section) 101 to be constant. The relationship between the vacuum level in space 111 and the Torricelli vacuum height Ht is shown in Figure 2(A).

[0024] When the degree of vacuum in the space 111 is 2 kPa, the Torricelli height Ht is 10.3 m, and when the degree of vacuum in the space 111 is 20 kPa, the Torricelli height Ht is 8.3 m. In other words, in an area where the tide level fluctuation range is 2 m, the device will be operated with a degree of vacuum in the space 111 between 2 kPa and 20 kPa. In this embodiment, water level sensors H112 and L113 are provided, and the height of the liquid 100 inside the CO2 release tank (storage section) 101 is kept within a certain range by controlling the vacuum pump so that the water level is between the sensors. However, other methods for keeping the height of the liquid 100 within a certain range may be used.

[0025] The results of measuring the degree of vacuum and the carbon dioxide dissolution rate of the liquid are shown in Figure 2(B). The liquid 100 was pure water with carbon dioxide dissolved in it, and the results show the change in the carbon dioxide dissolution rate over time as the pressure was reduced for each pressure reduction pressure. When compared over a 10-minute pressure reduction period, the residual rate was 10% or less under all conditions, meaning that more than 90% of the carbon dioxide could be recovered. In this example, the pumping pump was driven to pump enough water to replace the liquid 100 inside the CO2 release tank (storage section) 101 every 10 minutes.

[0026] The liquid 100 inside the CO2 release tank (storage section) 101 may be vibrated by a vibration generator, and preferably, from the viewpoint of reducing energy costs, a configuration is used in which vibrations caused by devices such as a vacuum pump or a water pump are transmitted to the liquid 100. The liquid 100 may also be heated, and heating using solar energy, utilizing factory waste heat, geothermal energy, or green electricity is preferred. In this embodiment, the liquid 100 is seawater, but is not limited to seawater, and may also be any water source whose water level fluctuates, such as river water, lake water, pond water, or reservoir water.

[0027] [Second embodiment] An example of the functional configuration of the carbon dioxide recovery device of the present invention will be described below with reference to FIG.

[0028] The differences from the device shown in Figure 1 will be mainly described. In this embodiment, the liquid 100 with dissolved carbon dioxide is seawater, and the height between the liquid level of the liquid 100 inside the CO2 release tank (storage section) 101 and the drain outlet 110 is set to 10 m, which is the Torricelli vacuum height Ht. The degree of vacuum in the space 111 is approximately 2 kPa. The drain pipe 108 is equipped with a drain pipe length adjustment section 128 that can adjust the position height of the drain outlet 110, and the lower end of the drain pipe length adjustment section 128 is set to the position height of the drain outlet 110. In this embodiment, the drain outlet 110 is set to a position height that makes contact with the liquid 100 at high tide, but this is not limited to this.

[0029] At low tide, the head is 10 m or more, but pumping is possible as long as the difference between the pumping pump 109 and the liquid level of the liquid 100 inside the CO2 release tank (storage section) 101 is equal to or less than the Torricelli vacuum height. The liquid 100 inside the CO2 release tank (storage section) 101 reaches a water level that is equal to the Torricelli vacuum height Ht, which is determined by the height of the drain outlet 110 and the degree of vacuum in the space 111.

[0030] That is, the water level of the liquid 100 inside the CO2 release tank (storage section) 101 is adjusted by an adjuster that adjusts the vertical position height of the drain outlet 110. Such an adjuster adjusts the vertical distance between the water supply surface of the liquid facing the atmosphere and the water surface formed in the internal space by the liquid stored in the storage section.

[0031] In this embodiment, the Torricelli vacuum height Ht is set to 10 m, but this is not limited to this, and it may be, for example, 8 m, provided that the degree of vacuum in the space 111 corresponds to the Torricelli vacuum height Ht. Also, in this embodiment, the position height of the drain outlet 110 is fixed to coincide with high tide, but the position height of the drain outlet 110 may be changed depending on the tide level.

[0032] In this embodiment, the device was started up from its initial state, when no liquid 100 had been poured into the device, by reducing the pressure inside the CO2 release tank (storage section) 101 with the vacuum pump 102 and pumping water with the pumping pump 109 at high tide. At times other than high tide, the device may be started up by the method described above, for example, by bringing the drain outlet 110 into contact with the seawater surface using the drain pipe length adjustment section 128, or an extension pipe may be provided on the drain pipe 108 so that the drain outlet 110 comes into contact with the sea surface.

[0033] [Third embodiment] An example of the functional configuration of the carbon dioxide recovery device of the present invention will be described below with reference to FIG.

[0034] The following mainly describes the differences from the first embodiment. A water supply tank 114, which is a pool on the water supply side, and a drain tank 115, which is a pool on the drain side, are provided at the water supply port and drain outlet 111 of the water supply pipe 107, respectively. The water supply tank 114 opens a water inlet valve 116 at high tide to inject liquid 100. The drain tank 115 opens a drain valve 117 at low tide to drain liquid 100. In this embodiment, the water supply tank water level 129 is always kept higher than the drain tank water level 130, and the liquid 100 is configured to circulate without an auxiliary circulation pump. Therefore, the liquid level of the liquid 100 inside the CO2 release tank (storage section) 101 is adjusted by the water level of the drain tank water level 130.

[0035] The timing of the aforementioned water injection and drainage does not necessarily have to be strictly at high tide or low tide, but water can be injected when the tide is sufficiently high and drained when the tide is sufficiently low. The sizes of water supply tank 114 and drainage tank 115 are determined by the amount of liquid 100 circulating in the carbon dioxide capture device and the time period during which the tide level fluctuates, and they should be large enough so that fluctuations in water supply tank water level 129 and drainage tank water level 130 are smaller than fluctuations in the tide level. It is desirable that water level sensors (not shown) be installed in water supply tank 114 and drainage tank 115 and that the opening and closing of water injection valve 116 and drainage valve 117 be automatically controlled by a control device.

[0036] [Fourth embodiment] An example of the functional configuration of the carbon dioxide recovery device of the present invention will be described below with reference to FIG.

[0037] The differences from the first embodiment will be mainly described. An adjuster 121, which is an adjuster that adjusts the height in the vertical direction using a hydraulic jack, and a top plate 122 are provided on a base 120 installed on the ground. A CO2 release tank (storage unit) 101 is installed on the top plate 122, making it possible to adjust the height of the entire carbon dioxide capture device in the vertical direction. The height is adjusted by the adjuster 121 so that the water surface of the liquid 100 is between the water level sensor H112 and the water level sensor L113. It is desirable that the height adjustment by the adjuster 121 be automatically controlled by a control device.

[0038] In this embodiment, the carbon dioxide capture device as a whole is configured to have its height adjusted in the vertical direction, but it is not limited to a configuration in which the height of the entire device is adjustable as long as the height of the CO2 release tank (storage unit) 101 can be adjusted. Also, the liquid 100 in an atmospheric pressure equilibrium state is in an over-equilibrium state due to reduced pressure, and vibration accelerates the CO2 release rate from the liquid 100. The CO2 release rate from the liquid 100 may be accelerated by vibrating the CO2 release tank (storage unit) 101 with the adjuster 121.

[0039] [Fifth embodiment] An example of the functional configuration of the carbon dioxide recovery device of the present invention will be described below with reference to FIG.

[0040] The differences from the first embodiment will be mainly explained. The water surface height of the liquid 100 inside the CO2 release tank (storage section) 101 is set to 10 m, which is the Torricelli vacuum height, at high tide, and is set to 10 m or more at low tide. A water pump 109 installed at the middle position of the water pumping pipe 107 makes it possible to pump water to a height of 10 m or more. A valve 127 for adjusting the flow rate is installed in the drain pipe 108, and the water surface height of the liquid 100 inside the CO2 release tank (storage section) 101 is kept constant by preventing the liquid 100 from flowing at more than a certain amount even when the water level is above the Torricelli vacuum height.

[0041] That is, by limiting the amount of water discharged, the water surface height of the liquid 100 inside the CO2 release tank (storage section) 101 is adjusted. In this embodiment, the amount of water discharged of the liquid 100 is adjusted by controlling the valve 127 so that the water surface of the liquid 100 is between the water level sensor H112 and the water level sensor L113. On the other hand, as long as the amount of water discharged can be limited, a thin drain pipe or curved piping may be used so that the amount of water discharged is small relative to the amount of water supplied, or a drain pump that can adjust the flow rate may be provided.

[0042] In this embodiment, the water vapor removed by the water vapor filter 103 is stored as distilled water in a distilled water tank 124. The distilled water tank 124 and the water vapor filter 103 are positioned at the same height such that the height of the distilled water tank 124 relative to the water vapor filter 103 is equal to or lower than the Torricelli vacuum height, and the distilled water is stored in the distilled water tank 124 by its own weight. The stored distilled water may be used as drinking water, agricultural water, or industrial water. Hydrogen may also be produced from the distilled water, and hydrocarbons may be produced from the produced hydrogen and recovered carbon dioxide.

[0043] In this embodiment, a configuration is provided in which multiple CO2 storage units 106 are provided, and a configuration is adopted in which the CO2 storage unit 106 filled with carbon dioxide is switched to fill another CO2 storage unit 106 until the pressure sensor 126 detects a certain pressure. The valve 127 of the CO2 storage unit not being filled with carbon dioxide is closed.

[0044] A pressure sensor 125 is provided in the CO2 buffer tank 104, and when the pressure sensor 125 indicates a predetermined pressure or higher, the compressor 105 is operated intermittently to fill carbon dioxide into the CO2 storage unit (accumulator) 106. The configuration for storing distilled water obtained by the water vapor filter, the configuration for switching between filling the multiple CO2 storage units (accumulators), and the intermittent operation of the compressor are examples of the device configuration of the present invention, and are not intended to limit the device configuration. [Explanation of symbols]

[0045] 100 liquid 101 CO2 release tank (storage section) 102 Vacuum pump 103 Water vapor filter 104 CO2 buffer tank 105 Compressor 106 CO2 storage unit (accumulator) 107 Lifting pipe 108 Drain pipe 109 Water Pump 110 Drain port 111 Space 112 Water level sensor H 113 Water level sensor L

Claims

1. a storage section configured by a partition wall that separates the atmosphere from the internal space, and that stores a liquid in which carbon dioxide is dissolved in the internal space; a suction unit that lifts the liquid by sucking gas present in the internal space; an adjuster that adjusts the vertical distance between a water supply surface of the liquid facing the atmosphere and a water surface formed in the internal space by the stored liquid; an accumulation unit that accumulates carbon dioxide recovered from the internal space; A carbon dioxide capture device equipped with the above.

2. 2. The carbon dioxide recovery device according to claim 1, wherein the carbon dioxide is recovered from a vacuum space in a Torricelli chamber formed as the liquid is lifted.

3. 2. The carbon dioxide recovery device according to claim 1, wherein the adjuster is an adjuster that controls the degree of vacuum in the storage section.

4. The carbon dioxide recovery device according to claim 1 , wherein the adjuster is a position height of a drain outlet for discharging liquid from the storage portion.

5. 2. The carbon dioxide recovery device according to claim 1, wherein the adjuster adjusts the liquid level in accordance with a liquid level in a pool provided at a water inlet for the liquid and a liquid level in a pool provided at a drain outlet for the liquid.

6. 2. The carbon dioxide recovery device according to claim 1, wherein the adjuster is a height adjuster that adjusts the height of the storage section.

7. 2. The carbon dioxide recovery device according to claim 1, wherein the adjuster controls a pumping amount of the liquid pumped into the storage portion and a drainage amount of the liquid drained from the storage portion.

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