A pressure self-discharging CO2 sequestration method

Abstract

The present invention discloses a pressure self-discharging CO₂ sequestration method, including the steps of: injecting liquid CO₂ into a storage tank; transporting the storage tank to an ocean sequestration area by a ship; putting the storage tank into seawater; opening a discharge device, and CO₂ flows out to achieve pressure release; when the storage tank sinks to a depth where the external seawater pressure reaches the opening pressure of the injection device, the injection device is opened, and seawater flows into the storage tank; when the storage tank sinks to the CO₂ sequestration depth, the injection device and the discharge device are fully opened, and liquid CO₂ flows out of the storage tank until the discharge is completed. The present invention provides a self-recycling CO₂ transportation storage tank, which can be recycled repeatedly, relies on pressure control, is safe and reliable in operation, suspends and discharges liquid CO₂ in seawater, and solves the problems of adsorption by submarine sediment and non-recyclability.

Description

Technical Field

[0001] The present invention relates to the sequestration of CO2, and more specifically, to a method for deep - sea sequestration of liquid CO2 in the ocean floor through a pressure - self - discharging storage tank. Background Art

[0002] In the prior art, for the deep - sea sequestration of liquid CO2 through pipeline sequestration, pipelines over 1000 meters need to be laid, as well as large - scale transportation equipment with a transportation pressure above 100 bar, resulting in a very high cost for the deep - sea sequestration of liquid CO2. Moreover, discontinuous sequestration will cause the gasification and escape of liquid CO2. Summary of the Invention

[0003] In view of the above problems, the present invention aims to provide a method for deep - sea sequestration of CO2 with low cost, high efficiency, and the reusable liquid CO2 storage tank.

[0004] To achieve the above - mentioned purpose, the present invention provides a pressure - self - discharging CO2 sequestration method, including the following states:

[0005] S1. Inject liquid CO2 into the storage tank. The storage tank includes a tank body for storing liquid CO2 and provided with a heat - insulating layer. On both sides of the tank body, a discharge device and an injection device with a one - way valve body are respectively arranged. The center of gravity of the tank body is biased towards the side of the discharge device; a nitrogen - generating device is arranged on the side of the injection device inside the tank body; the discharge device includes a pressure - controlled relief device.

[0006] S2. Transport the storage tank to the ocean sequestration area by ship.

[0007] S3. Put the storage tank into seawater. Due to the action of the center of gravity, the storage tank sinks in a vertical state, and the side of the discharge device is at the bottom end.

[0008] S4. The pressure inside the storage tank increases. When it reaches the opening pressure of the relief device, the relief device opens to achieve pressure relief.

[0009] S5. When the external seawater pressure reaches the opening pressure of the injection device as the storage tank sinks, the injection device opens, and seawater flows into the storage tank. [[ID=3,3]]

[0010] S6. When the storage tank sinks to the CO2 sequestration depth, the injection device and the discharge device are fully opened, and liquid CO2 flows out of the storage tank until the discharge is completed. The external seawater completely enters the storage tank, and then the injection device is closed.

[0011] S7. The nitrogen - generating device works to generate nitrogen. The storage tank discharges seawater and floats; the discharge device is closed.

[0012] S8. The storage tank floats to the sea surface and is recycled again.

[0013] In a preferred embodiment, the center of gravity of the storage tank is biased towards the discharge device by fixing heavy weights.

[0014] In a preferred embodiment, the storage tank is fixed with a satellite positioning device for positioning during recycling.

[0015] In a preferred embodiment, the storage tank is provided with position monitoring equipment for determining the depth of the storage tank's sinking; the injection device and the discharge device are respectively provided with remote control opening and closing devices for opening and closing when the storage tank is located at the determined depth.

[0016] In the optimal embodiment, the maximum allowable pressure of the storage tank is 30 bar, and the minimum CO2 storage depth in step S6 is 1000 m.

[0017] In summary, for the ocean storage of liquid CO2, regarding the path problem from the sea surface to the deep sea, the present invention has invented a self-recycling CO2 transportation and storage tank that can be recycled repeatedly, solving the cost problem; invented a pressure self-discharging CO2 transportation and storage tank, which relies on pressure control and is safe and reliable in operation, solving the problem of manual control; invented a suspended CO2 transportation and storage tank that discharges liquid CO2 in suspension in seawater, solving the problem of adsorption by submarine sediment and non-recyclability. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the liquid CO2 transportation and storage tank used in the method of the present invention.

[0019] Figure 2 is Figure 1 A partial structural diagram of the discharge device in the storage tank in

[0020] Figure 3 It is a schematic diagram of the state of a ship carrying a liquid CO2 transportation and storage tank in the method of the present invention.

[0021] Figure 4 It is a schematic diagram of the process of realizing CO2 in the storage area.

[0022] Figure 5 It is a schematic diagram of the state of the storage tank after completing the release of liquid CO2.

[0023] Figure 6 It is a schematic diagram of the process of the storage tank returning.

[0024] Figure 7 It is a schematic diagram of the state of the storage tank being recycled.

[0025] Figure 8It is a schematic diagram of the state when the ship completes the recovery of the storage tank. Detailed implementation manners

[0026] As Figure 1 and 2 shown, the present invention designs a self-recovery type, pressure self-discharging type, and floating CO2 transportation and storage tank, which includes a tank body 5 for storing liquid CO2. The strength of the tank body 5 is designed according to the storage water depth. It has an injection device 1 applying pressure control, a discharge device 2 applying pressure control, a positioning system device 3, a chemical method nitrogen generation device 4, and a pressure-controlled relief device 6. The liquid CO2 tank body 5 is designed in a capsule shape. The shape design of the capsule is beneficial to keep the upper and lower ends constant during the sinking and floating processes, avoid flipping, and facilitate pressure control. Due to the symmetrical structure of the tank body 5, the center of gravity is at the center, and most of the device weights are concentrated at one end of the discharge device 2. Finally, the overall center of gravity design of the liquid CO2 tank is biased towards one end of the discharge device 2, so that the tank body sinks vertically along the longitudinal direction of the tank body when it sinks.

[0027] The tank body 5 for storing liquid CO2 can withstand internal and external pressures above 30 bar, and is preferably designed in a capsule shape, which is beneficial to keep the upper and lower ends constant during the sinking and floating processes, avoid flipping, and facilitate pressure control.

[0028] In addition, for the injection device 1 applying pressure control involved in the present invention, when the external pressure of the tank body 5 caused by seawater is greater than the internal pressure, due to the pressure effect, the pressure-controlled injection device 1 automatically opens. In the optimal mode, for the injection device 1 applying pressure control, by designing the opening size of the injection device 1, the flow rate of seawater flowing in is controlled to keep the pressure difference still increasing with the increase of the sinking depth; in addition, when a large amount of seawater flows into the CO2 tank and the internal and external pressure difference of the liquid CO2 tank is zero, the pressure-controlled injection device 1 automatically closes. In addition, for a similar device involved in the Chinese patent "An industrial bus type ship LNG fuel security control device" (patent number CN201721324589.6), the injection device 1 of the present invention can be used after simple modification and experimental determination of parameters.

[0029] In addition, for the discharge device 2 applying pressure control involved in the present invention, when the liquid CO2 tank sinks to 1000 m underwater and the external pressure of the tank body 5 caused by seawater reaches the designed pressure, due to the pressure effect, the pressure-controlled discharge device 2 automatically opens. In the preferred mode, when nitrogen is filled in the CO2 tank, the discharge device 2 is designed with a gas escape device 7 to prevent nitrogen from discharging and the tank from sinking. For a similar device involved in the Chinese patent "An industrial bus type ship LNG fuel security control device" (patent number CN201721324589.6), the discharge device 2 of the present invention can be used after simple modification and experimental determination of parameters.

[0030] In addition, for the pressure-controlled relief device 6 involved in the present invention, during the sinking process of the liquid CO2 tank, the liquid CO2 is heated by seawater, the temperature of the liquid CO2 will rise, the internal pressure will increase, and the pressure-controlled relief device 6 will automatically open to relieve the pressure and maintain the internal pressure at 30 bar. To ensure the strength of the tank body 5 and reduce the openings on the tank body 5, the pressure-controlled relief device 6 is arranged on the pressure-controlled discharge device (2). The relief device can be selected as a similar device involved in the Chinese patent CN202021137650.8 "An LPG ship safety release pipeline device", and it can be used after determining the parameters through simple transformation and experiments.

[0031] For the chemical method nitrogen generation device 4 involved in the present invention, when the liquid CO2 tank sinks to 1000 m underwater and the external pressure of the tank body 5 caused by seawater reaches the design pressure, due to the pressure effect, the pressure-controlled nitrogen generation device 4 will automatically open to generate nitrogen by applying a chemical method. The nitrogen generation device 4 can be selected as a similar device involved in the Chinese patent CN201910182443.X "An emergency life-saving device for sunken submarines and surface ships using chemical energy", and it can be used after determining the parameters through simple transformation and experiments.

[0032] For the positioning system device 3 involved in the present invention, when the liquid CO2 tank floats out of the sea surface by buoyancy, the positioning system 3 is applied to find the tank.

[0033] The operation process of the present invention will be specifically described:

[0034] As Figure 4 shown, in the deployment state. First, the bottom hatch cover of the deployment and recovery ship is opened, and the liquid CO2 tank is deployed into the sea. One end of the discharge device 2 faces downward. Due to the center of gravity being below and the center of buoyancy being in the center, the liquid CO2 tank is in a vertical state. Since the liquid CO2 tank is heavier than seawater, the liquid CO2 tank sinks.

[0035] During the sinking process of the liquid CO2 tank, the liquid CO2 is heated by seawater above 0 °C, the temperature of the liquid CO2 will rise, the internal pressure will increase, and the pressure-controlled relief device 6 will automatically open to relieve the pressure and maintain the internal pressure at 30 bar.

[0036] When the sinking reaches a depth of 300 m, the external pressure of the tank body 5 caused by seawater is 31 bar, which is greater than the internal pressure. Due to the pressure effect, the pressure-controlled injection device 1 will automatically open and seawater will flow in.

[0037] The liquid CO2 tank continues to sink, and a part of the seawater enters the tank body 5, reducing the pressure difference of the tank body 5; since the greater the sinking speed of the CO2 tank, the greater the resistance of the seawater, when reaching a certain speed, the resistance of the seawater is equal to the gravity of the CO2 tank, and the sinking speed of the CO2 tank no longer increases. The opening size of the injection device 1 is designed according to the calculated sinking speed of the CO2 tank to control the inflow speed of the seawater and keep the pressure difference within 30 bar, which still increases with the increase of the sinking depth.

[0038] The tank body 5 containing liquid CO2 and seawater continues to sink. When the liquid CO2 tank sinks to 1000 m underwater, at the same time, by adjusting the opening size of the injection device 1, when the pressure difference increases to 20 - 30 bar or above, due to the pressure effect, the pressure-controlled discharge device 2 opens, and a large amount of seawater flows into the CO2 tank. The pressure difference inside and outside the liquid CO2 tank is zero, and the pressure-controlled injection device 1 closes. At this time, as Figure 5 shown, when the liquid CO2 tank sinks to 1000 m underwater, the liquid CO2 flows out of the tank by gravity and dissolves in the sea to achieve the purpose of sequestration.

[0039] At the same time, the nitrogen generation device 4 is opened by applying pressure control, and nitrogen is generated by chemical methods. Since the gas density is small, it fills the upper part of the CO2 tank, expels the water in the tank body 5, and the tank floats. The discharge device 2 is designed with a gas escape device 7 to prevent nitrogen from discharging and the tank from sinking.

[0040] As Figure 6 shown, relying on the buoyancy, the tank body 5 floats out of the sea surface.

[0041] As Figure 7 shown, the positioning system 3 is applied to find the tank.

[0042] As Figure 8 shown, the bottom hatch cover is opened, and a delivery and recovery ship is used to recover the tank for repeated use.

[0043] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A pressure self-discharging CO2 sequestration method, characterized in that, Including the following states: S1. Liquid CO2 is injected into a storage tank. The storage tank includes a tank body (5) for storing liquid CO2 and provided with a heat insulation layer. On both sides of the tank body (5), a discharge device (2) and an injection device (1) with a one-way valve body are respectively arranged. The center of gravity of the tank body (5) is biased towards the side of the discharge device (2); a nitrogen generation device (4) is arranged on one side of the injection device (1) inside the tank body (5); the discharge device (2) includes a pressure-controlled relief device (6); S2. The storage tank is transported to a marine storage area by a ship; S3. The storage tank is put into seawater. Due to the action of the center of gravity, the storage tank sinks in a vertical state, and the side of the discharge device (2) is at the bottom end; S4. The pressure inside the storage tank increases and reaches the opening pressure of the relief device (6). The relief device (6) opens, and CO2 flows out to achieve pressure relief; S5. When the storage tank sinks to a depth where the external seawater pressure reaches the opening pressure of the injection device (1), the injection device (1) opens, and seawater flows into the storage tank; S6. When the storage tank sinks to the CO2 storage depth, the injection device (1) and the discharge device (2) are fully opened, and liquid CO2 flows out of the storage tank until the discharge is completed. The external seawater completely enters the storage tank, and the injection device (1) is closed; S7. The nitrogen generation device (4) works to generate nitrogen. The storage tank discharges seawater, and the storage tank floats; the discharge device (2) is closed; S8. The storage tank floats to the sea surface and is recycled again.

2. The pressure self-discharging CO2 sequestration method according to claim 1, characterized in that, The center of gravity of the storage tank is biased towards the side of the discharge device (2) by fixing heavy objects.

3. The pressure self-unloading CO2 sequestration method according to claim 1, wherein The storage tank is fixed with a satellite positioning device (3) for positioning during recovery.

4. The pressure self-discharging CO2 sequestration method according to claim 1, wherein The storage tank is provided with position monitoring equipment for determining the sinking depth of the storage tank; the injection device (1) and the discharge device (2) are respectively provided with remote control opening and closing devices for opening and closing when the storage tank is monitored to be at a determined depth.

5. The pressure self-unloading CO2 sequestration method according to claim 1, characterized in that, The maximum allowable pressure of the storage tank is 30 bar.

6. The pressure self-unloading CO2 sequestration method according to claim 1, wherein The minimum CO2 storage depth in step S6 is 1000 m.

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