A CO2 Offshore Transfer and Sequestration System

Abstract

The present invention discloses a CO2 offshore transfer and storage system, which consists of five parts: CO2 transmission, CO2 loading and unloading, CO2 transportation, CO2 injection, and CO2 storage; it has the conditions for terminal loading. The onshore CO2 storage terminal is transported to the CO2 filling device through an onshore pipeline to fill the CO2 transport ship. After arriving at the destination, it is unloaded at the terminal through the CO2 transfer system and then transported through a pipeline to the CO2 injection module for injection and storage in an onshore or subsea CO2 storage site. If there are no conditions for terminal loading, the onshore CO2 storage terminal is transported to the offshore floating CO2 storage device through a pipeline. The CO2 transport ship is moored to it by side-by-side mooring or tandem mooring, and the CO2 filling is completed through a hose transmission. After the CO2 transport ship arrives at the target sea area, it is transported to the offshore CO2 injection platform through an internal turret device, a subsea pipeline, and a subsea riser, and is injected into the subsea CO2 storage site through a subsea wellhead for storage. The present invention is applicable to the offshore transfer and storage of CO2 under any conditions.

Description

Technical Field

[0001] The present invention relates to the field of carbon dioxide (CO2) capture, transportation, and storage (CCUS), and more specifically, it refers to the process of separating CO2 from industrial processes, energy utilization, or the atmosphere and storing it in terrestrial or marine geological formations to achieve permanent CO2 emission reduction. Background Art

[0002] Marine carbon storage has great potential compared to onshore carbon storage. It is far from inhabited areas and has more advantages in terms of reliability and environmental friendliness. Although marine carbon storage is slightly more costly than onshore carbon storage, due to the flexibility of maritime transportation, the construction of subsea storage can serve a wider range of carbon sources. Summary of the Invention

[0003] In view of the above problems, it is necessary to invent a CO2 maritime transfer and storage system to achieve efficient CO2 transportation, thereby providing conditions for CO2 storage, promoting the development of the carbon trading market, and realizing high economic value.

[0004] A CO2 maritime transfer and storage system of the present invention mainly consists of five parts: CO2 transmission, CO2 loading and unloading, CO2 transportation, CO2 injection, and CO2 storage.

[0005] When the terminal has the condition of loading at the dock, the CO2 onshore storage terminal is transported to the CO2 filling device through an onshore pipeline, and the CO2 transport ship is filled. After arriving at the destination, it is unloaded at the dock through the CO2 transfer system and then transported through a pipeline to the CO2 injection module and injected into the onshore or subsea CO2 storage site for storage.

[0006] When the terminal does not have the condition of loading at the dock, the CO2 onshore storage terminal is transported to the CO2 floating storage device at sea through a pipeline. The CO2 transport ship is moored to it by using the way of tandem mooring or alongside mooring, and the CO2 filling is completed through a hose transmission. After the CO2 transport ship arrives at the target sea area, it is moored and positioned to the CO2 floating storage device with an internal turret by using the way of tandem mooring or alongside mooring, and the CO2 unloading is completed through a hose transmission. Then it is transported to the CO2 offshore injection platform through the internal turret device, subsea pipeline, and underwater riser, and injected into the subsea CO2 storage site through the subsea wellhead for storage.

[0007] When the terminal does not have the condition of loading at the dock, the CO2 onshore storage terminal is transported to the CO2 floating storage device with an internal turret at sea through a pipeline. After the CO2 floating storage device with an internal turret arrives at the target sea area, it is transported to the CO2 offshore injection platform through the internal turret device, subsea pipeline, and underwater riser, and injected into the subsea CO2 storage site through the subsea wellhead for storage.

[0008] Above, onshore pipelines, submarine pipelines, risers in water, and hoses must all have the characteristics of heat insulation and pressure resistance. The phase state of CO2 transported in the pipeline can be gaseous, liquid, and supercritical state.

[0009] When the CO2 in the pipeline is in a liquid state, the pressure range in the pipeline is 0.4 - 7.???MPa. When the CO2 in the pipeline is in a supercritical state, the temperature in the pipeline > 31.3 °C and the pressure in the pipeline > 7.???MPa. When the CO2 in the pipeline is in a gaseous state, the pressure range in the pipeline is 0 - 7.???MPa.

[0010] The CO2 carrier uses a C-type tank for storage, and the CO2 storage pressure in the C-type tank is 0.4MPa - 2.1MPa.

[0011] Adopting the technical solution of the present invention can achieve the following beneficial effects: it is applicable to CO2 offshore transfer and storage under any conditions. The CO2 offshore transfer and storage system of the present invention can realize the efficient transportation of CO2, thus providing conditions for the storage of CO2, and can also promote the development of the carbon trading market and achieve high economic value.

[0012] In order to achieve the storage purpose of the present invention, the present invention provides a CO2 deep-sea ocean storage method with low cost, high efficiency, and the liquid CO2 storage tank can be reused. It includes the following states:

[0013] S1. Inject liquid CO2 into the storage tank. The storage tank includes a tank body for storing liquid CO2 and provided with a heat insulation 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 generation device is arranged on one side of the injection device in the tank body; the discharge device includes a pressure-controlled relief device.

[0014] S2. Transport the storage tank to the ocean storage area by ship.

[0015] 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.

[0016] S4. The pressure in the storage tank increases. When it reaches the opening pressure of the relief device, the relief device opens to realize pressure relief.

[0017] 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.

[0018] It should be noted that there are some unclear values (such as "7.???MPa") in the original text which are retained as they are in the translation.S6. When the storage tank sinks to the CO2 storage depth, the injection device and the discharge device are fully opened, and the liquid CO2 flows out of the storage tank until the discharge is completed. Then, the external seawater completely enters the storage tank, and the injection device is closed.

[0019] S7. The nitrogen generation device operates to generate nitrogen. The storage tank discharges seawater and floats upward. The discharge device is closed.

[0020] S8. The storage tank floats out of the sea surface and is recycled again.

[0021] In a preferred manner, the storage tank realizes the center of gravity bias towards the side of the discharge device through fixed weights.

[0022] In a preferred manner, the storage tank is fixed with a satellite positioning device for positioning during recovery.

[0023] In a preferred manner, 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.

[0024] In the optimal manner, the maximum allowable pressure of the storage tank is 30 bar, and the minimum CO2 storage depth in step S6 is 1000 m.

[0025] In summary, for the marine storage of liquid CO2, aiming at 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, relying on pressure control, with safe and reliable operation, solving the problem of manual control; invented a suspended CO2 transportation and storage tank that suspends and discharges liquid CO2 in seawater, solving the problem of adsorption by submarine sediment and non-recyclability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the general layout diagram of the onshore CO2 storage of the present invention.

[0027] Figure 2 It is the general layout diagram of the submarine CO2 storage of the present invention.

[0028] Figure 3 It is the first part of the system flow chart of the present invention.

[0029] Figure 4 It is the second part of the system flow chart of the present invention.

[0030] Figure 5 It is the third part of the system flow chart of the present invention.

[0031] Figure 6 It is the fourth part of the system flow chart of the present invention.

[0032] Figure 7 It is a schematic structural diagram of the liquid CO2 transportation and storage tank used in the method of the present invention.

[0033] Figure 8 It is Figure 7 A partial structural diagram of the discharge device in the storage tank in

[0034] Figure 9 It is a schematic diagram of the state of the liquid CO2 transportation and storage tank carried by a ship in the method of the present invention.

[0035] Figure 10 It is a schematic diagram of the process of realizing CO2 in the storage area.

[0036] Figure 11 It is a schematic diagram of the state of the storage tank after completing the release of liquid CO2.

[0037] Figure 12 It is a schematic diagram of the process of the storage tank returning.

[0038] Figure 13 It is a schematic diagram of the state of the storage tank being recovered.

[0039] Figure 14 It is a schematic diagram of the state of the ship after completing the recovery of the storage tank.

[0040] Some of the marks in the attached drawings are respectively:

[0041] 1 - CO2 generated by industrial activities, 2 - CO2 capture module, 3 - Onshore CO2 storage terminal, 4 - Onshore CO2 filling arm, 5 - Onshore CO2 transportation pipeline, 6 - Submarine CO2 transportation pipeline, 7 - Tank-type CO2 transport ship, 8 - CO2 transport ship using tandem mooring, 9 - Floating CO2 storage device equipped with an internal turret, 10 - CO2 transport ship using alongside mooring, 11 - Catenary single point mooring device, 12 - Floating hose, 13 - Subsea riser, 14 - Mooring cable, 15 - Mooring anchor chain, 16 - Soft yoke single point mooring device, 17 - Transfer hose, 18 - Floating CO2 storage device, 19 - Jacket-type CO2 boosting and transfer platform, 20 - CO2 boosting and transfer module, 21 - CO2 loading and unloading terminal, 22 - CO2 transfer system, 23 - CO2 injection module, 24 - Onshore CO2 storage site. 25 - Submarine CO2 storage site, 26 - Submarine wellhead, 27 - Jacket-type CO2 filling platform, 28 - CO2 filling module. Detailed implementation manners

[0042] Figure 1This is the general layout diagram for onshore CO2 sequestration. The CO2 generated by industrial activities is collected by the 2-CO2 capture module and stored in the 3-onshore CO2 storage terminal in liquid form. When CO2 needs to be sequestered, since the distance to the 26-onshore sequestration site is relatively far, CO2 transportation is required. Through the 5-onshore CO2 pipeline, the liquid CO2 is transported to the 4-onshore CO2 filling arm to fill the 7-CO2 transport ship docked at the wharf. It can also be transported through the 6-submarine CO2 pipeline and the 13-subsea riser to transfer the CO2 stored in the 3-onshore CO2 storage terminal to the 11-catenary single point mooring device, and then through the 12-floating hose to the 7-CO2 transport ship for filling. It can also be transported through the 6-submarine CO2 pipeline and the 13-subsea riser to transfer the CO2 stored in the 3-onshore CO2 storage terminal to the 16-soft yoke single point mooring device, and then through the 17-jumper transfer hose to the 7-CO2 transport ship for filling.

[0043] To improve the storage and transportation efficiency of CO2, a 9-floating CO2 storage device equipped with an internal turret can be set up in the nearshore sea area. The CO2 generated by industrial activities is collected by the 2-CO2 capture module and then transported in liquid form through the 6-submarine CO2 pipeline to the 9-floating CO2 storage device equipped with an internal turret, and then transferred to the 8-CO2 transport ship using tandem mooring and the 10-CO2 transport ship using alongside mooring. To improve the loading and unloading efficiency of CO2, multiple 11-catenary single point mooring devices can be set up. The 11-catenary single point mooring devices are fixed to the seabed through the 15-mooring chain. The CO2 stored in the 9-floating CO2 storage device equipped with an internal turret is transported to the 11-catenary single point mooring device through the 6-submarine pipeline and the 13-subsea riser. The 7-CO2 transport ship is moored to the 11-catenary single point mooring device through the 14-mooring cable, and the

[0044] CO2 is transferred from the 11-catenary single point mooring device to the 7-CO2 transport ship. In addition to the above modes, the CO2 generated by industrial activities is collected by the 2-CO2 capture module and then transported in liquid form through the 6-submarine CO2 pipeline to the 18-floating CO2 storage device, and the CO2 is directly transported by it.

[0045] For the onshore CO2 sequestration method, when the 7-CO2 transport ship sails to the target sea area, if it meets the conditions for unloading at the wharf, it berths at the 21-wharf, and the CO2 is transferred to the 3-onshore CO2 storage terminal through the 22-CO2 transfer system. The CO2 is transported to the 23-CO2 injection module through the 5-onland pipeline and injected into the 24-onshore CO2 sequestration site for sequestration.

[0046] After the floating CO2 storage device with an in-equipment turret full of CO2 reaches the target sea area, if the target sea area does not have the conditions for terminal unloading, the CO2 can be transported over a long distance to the onshore CO2 storage terminal 3 through the underwater riser 13 and the pre-laid subsea CO2 pipeline 6 and the onshore pipeline 5, and the CO2 is transported to the CO2 injection module 23 through the onshore pipeline 5 and injected into the onshore CO2 sequestration site 24 for sequestration. The CO2 can also be transported over a long distance through the jacket-type CO2 booster transfer platform. The CO2 carrier 7 and the floating CO2 storage device 18 are moored and connected through the mooring cable 14 and the catenary single point mooring device 11, and the CO2 is transported to the catenary single point mooring device 11 through the floating hose 12. The CO2 carrier 7 and the floating CO2 storage device 18 can also be moored and connected to the soft yoke single point mooring device 16, and the CO2 is transported to the soft yoke single point mooring device 16 through the jumper transfer hose 17. Then the CO2 is transported to the jacket-type CO2 booster transfer platform 19 through the subsea pipeline 6 and the underwater riser 13, pressurized by the CO2 booster transfer module 20 and then transported to the CO2 injection module 23 through the subsea CO2 pipeline 6 and the onshore CO2 pipeline 5 and injected into the onshore CO2 sequestration site 24 for sequestration.

[0047] In order to improve the unloading efficiency, multiple catenary single point mooring devices 11 can also be set up. After the floating CO2 storage device with an in-equipment turret completes the transfer, it serves as a CO2 transfer station. The CO2 carriers 8 using tandem mooring and 10 using alongside mooring are moored and connected to the floating CO2 storage device with an in-equipment turret to transfer CO2 to it. In addition, the CO2 carrier 7 can also be moored and connected to the catenary single point mooring device 11 through the mooring cable 14, and the CO2 is transported to the catenary single point mooring device 11 through the floating hose 12, and then the CO2 is transported to the floating CO2 storage device with an in-equipment turret through the subsea pipeline 6 and the underwater riser 13 for storage. The CO2 can be transported to the onshore CO2 storage terminal 3 through the underwater riser 13 and the pre-laid subsea CO2 pipeline 6 and the onshore pipeline 5, and the CO2 is transported to the CO2 injection module 23 through the onshore pipeline 5 and injected into the onshore CO2 sequestration site 24 for sequestration.

[0048] There are also many abandoned oil fields at sea. Figure 2This is the general layout diagram for the subsea sequestration of CO2. In the diagram, the CO2 generated by industrial activities (1) is collected by the CO2 capture module (2) and stored in the onshore CO2 storage terminal (3) in liquid form. When CO2 needs to be sequestered, since the distance to the onshore sequestration site (26) is relatively far, CO2 transportation is required. Through the onshore CO2 transportation pipeline (5), the liquid CO2 is transported to the onshore CO2 filling arm (4) to fill the CO2 transport ship (7) docked at the wharf. It can also be transported through the subsea CO2 transportation pipeline (6) and the underwater riser pipe (13) to transfer the CO2 stored in the onshore CO2 storage terminal (3) to the catenary single point mooring device (11), and then through the floating hose (12) to transfer to the CO2 transport ship (7) for filling. It can also be transported through the subsea CO2 transportation pipeline (6) and the underwater riser pipe (13) to transfer the CO2 stored in the onshore CO2 storage terminal (3) to the soft yoke single point mooring device (16), and then through the jumper transfer hose (17) to transfer to the CO2 transport ship (7) for filling. After arriving at the destination, it berths at the wharf (21), and through the CO2 transfer system (22), the CO2 is transferred to the onshore CO2 storage terminal (3), and then the CO2 is transferred to the CO2 injection module (23). The CO2 is injected into the subsea CO2 sequestration site (25) through the subsea CO2 transportation pipeline (6) connected to the subsea wellhead (26).

[0049] To improve the storage and transportation efficiency of CO2, a floating CO2 storage device equipped with an internal turret (9) can be set up in the nearshore sea area. The CO2 generated by industrial activities (1) is collected by the CO2 capture module (2) and then transported in liquid form through the subsea CO2 transportation pipeline (6) to the floating CO2 storage device equipped with an internal turret (9), and then transferred to the CO2 transport ship using tandem mooring (8) and the CO2 transport ship using alongside mooring (10). To improve the loading and unloading efficiency of CO2, multiple catenary single point mooring devices (11) can be set up. The catenary single point mooring devices (11) are fixed to the seabed through the mooring anchor chain (15). The CO2 stored in the floating CO2 storage device equipped with an internal turret (9) is transferred to the catenary single point mooring device (11) through the subsea pipeline (6) and the underwater riser pipe (13). The CO2 transport ship (7) is moored to the catenary single point mooring device (11) through the mooring cable (14). The

[0050] CO2 is transferred from the catenary single point mooring device (11) to the CO2 transport ship (7). In addition to the above modes, the CO2 generated by industrial activities (1) is collected by the CO2 capture module (2) and then transported in liquid form through the subsea CO2 transportation pipeline (6) to the floating CO2 storage device (18), and the CO2 is directly transported by it.

[0051] After the floating CO2 storage device with an in-equipment turret fully loaded with CO2 reaches the target sea area, CO2 can be transported to the CO2 filling module on the 27- jacket-type CO2 filling platform through the 13- subsea riser and the pre-laid 6- subsea CO2 pipeline, and injected into the 25- subsea CO2 storage site by connecting the 13- subsea riser with the 26- subsea wellhead.

[0052] The 8- CO2 carrier using tandem mooring and the 10- CO2 carrier using alongside mooring are moored to the floating CO2 storage device with an in-equipment turret and transfer CO2 to it. In addition, the 7- CO2 carrier can also be moored to the 11- catenary single point mooring device through the 14- mooring cable, transfer CO2 to the 11- catenary single point mooring device through the 12 floating hose, and then transfer CO2 to the floating CO2 storage device with an in-equipment turret for storage through the 6- subsea pipeline and the 13- subsea riser. After that, CO2 is transported to the CO2 filling module on the 27- jacket-type CO2 filling platform through the 13- subsea riser and the pre-laid 6- subsea CO2 pipeline, and injected into the 25- subsea CO2 storage site by connecting the 13- subsea riser with the 26- subsea wellhead.

[0053] The 8- CO2 carrier using tandem mooring and the 10- CO2 carrier using alongside mooring are moored to the 18- floating CO2 storage device. The 18- floating CO2 storage device is moored to the 11- catenary single point mooring device through the 14- mooring cable, and transfers CO2 to the 11- catenary single point mooring device through the 12 floating hose. The 18- floating CO2 storage device can also be moored to the 16- soft yoke single point mooring device and transfer CO2 to the 16- soft yoke single point mooring device through the 17- jumper transfer hose. After that, CO2 is transported to the CO2 filling module on the 27- jacket-type CO2 filling platform via the 13- subsea riser and the 6- subsea pipeline, and injected into the 25- subsea CO2 storage site by connecting the 13- subsea riser with the 26- subsea wellhead.

[0054] Such as Figures 7 - 9The present invention designs a self-recycling, pressure-dumping, and floating CO2 transportation and storage tank, which includes a tank body 95 for storing liquid CO2. The strength of the tank body 95 is designed according to the depth of the storage water. It has an injection device 91 applying pressure control, a discharge device 92 applying pressure control, a positioning system device 93, a nitrogen generation device 94 applying chemical methods, and a pressure-controlled relief device 96. The liquid CO2 tank body 95 is designed in a capsule shape, and the shape design of the capsule is beneficial to keeping the upper and lower ends constant during the sinking and floating processes, avoiding flipping, and facilitating pressure control. Due to the symmetrical structure of the tank body 95, the center of gravity is at the center, and most of the device weights are concentrated at one end of the discharge device 92. Finally, the overall center of gravity design of the liquid CO2 tank is biased towards one end of the discharge device 92, so that the tank body sinks vertically along the longitudinal direction of the tank body when it sinks.

[0055] The tank body 95 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 keeping the upper and lower ends constant during the sinking and floating processes, avoiding flipping, and facilitating pressure control.

[0056] In addition, for the injection device 91 applying pressure control involved in the present invention, when the external pressure of the tank body 95 caused by seawater is greater than the internal pressure, due to the pressure effect, the pressure-controlled injection device 91 automatically opens. In the optimal mode, for the injection device 91 applying pressure control, by designing the opening size of the injection device 91, the inflow speed of seawater 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 91 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 91 of the present invention can be used after determining the parameters through simple transformation and experiments.

[0057] In addition, for the discharge device 92 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 95 caused by seawater reaches the design pressure, due to the pressure effect, the pressure-controlled discharge device 92 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 97 to prevent nitrogen from being discharged when the tank sinks. 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 determining the parameters through simple transformation and experiments.

[0058] In addition, for the pressure-controlled relief device 96 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 96 will automatically open to relieve the pressure and maintain the internal pressure at 30 bar. To ensure the strength of the tank body 95 and reduce the openings on the tank body 5, the pressure-controlled relief device 96 is arranged on the pressure-controlled discharge device 92. 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.

[0059] For the nitrogen generation device 94 using chemical methods involved in the present invention, when the liquid CO2 tank sinks to 1000 m underwater and the external pressure of the tank body 95 caused by seawater reaches the design pressure, due to the pressure effect, the pressure-controlled nitrogen generation device 94 will automatically open to generate nitrogen using chemical methods. The nitrogen generation device 94 can be selected as a similar device involved in the Chinese patent CN201910182443.X "An emergency rescue device for sunken submarines and surface ships using chemical energy", and it can be used after determining the parameters through simple transformation and experiments.

[0060] For the positioning system device 93 involved in the present invention, when the liquid CO2 tank floats out of the sea surface by buoyancy, the positioning system 93 is used to find the tank.

[0061] The operation process of the present invention is specifically described as follows:

[0062] As Figure 10 shown, in the deployment state. First, the bottom hatch cover of the deployment and recovery ship is opened, and the liquid CO2 tank is dropped into the sea. One end of the discharge device 92 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.

[0063] During the sinking process of the liquid CO2 tank, it 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 96 will automatically open to relieve the pressure and maintain the internal pressure at 30 bar.

[0064] When the sinking reaches a depth of 300 m, the external pressure of the tank body 95 caused by seawater is 31 bar, which is greater than the internal pressure. Due to the pressure effect, the pressure-controlled injection device 91 will automatically open and seawater will flow in.

[0065] The liquid CO2 tank continues to sink, and a part of the seawater enters the tank body 95, reducing the pressure difference of the tank body 95; since the greater the sinking speed of the CO2 tank, the greater the resistance of the seawater, when a certain speed is reached, 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 91 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.

[0066] The tank body 95 filled with 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 91, when the pressure difference is increased to 20 - 30 bar or more, due to the pressure effect, the pressure-controlled discharge device 92 opens, and a large amount of seawater flows into the CO2 tank, and the pressure difference inside and outside the liquid CO2 tank is zero, and the pressure-controlled injection device 91 closes. At this time, as Figure 11 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.

[0067] At the same time, the nitrogen generation device 94 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 95, and the tank floats. The discharge device 2 is designed with a gas escape device 97 to prevent nitrogen from being discharged and the tank from sinking.

[0068] As Figure 12 shown, relying on buoyancy, the tank body 95 floats out of the sea surface.

[0069] As Figure 13 shown, the positioning system 93 is applied to find the tank.

[0070] As Figure 14 shown, the bottom hatch cover is opened, and a launch and recovery ship is used to recover the tank for repeated use.

[0071] The above is only a preferred specific embodiment 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 of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A CO2 offshore transfer and storage system, characterized in that, The operation method is as follows: a. When there is a terminal loading at the dock, the CO2 onshore storage terminal transports CO2 to the CO2 filling device through an onshore pipeline, fills the CO2 carrier, unloads it at the dock through the CO2 transfer system after arriving at the destination, and injects it into the onshore or subsea CO2 storage site through a pipeline transmission to the CO2 injection module; When there is no terminal loading at the dock, methods b or c can be selected: b. The CO2 onshore storage terminal transports CO2 to the floating CO2 storage device at sea through a pipeline. The CO2 carrier moors with it by side-by-side mooring or tandem mooring, and completes the CO2 filling through a hose transmission. After the CO2 carrier arrives at the target sea area, it moors and positions with the floating CO2 storage device with an internal turret by side-by-side mooring or tandem mooring, completes the CO2 unloading through a hose transmission, and transmits it to the CO2 offshore injection platform through the internal turret device, subsea pipeline and underwater riser, and injects it into the subsea CO2 storage site through the subsea wellhead; c. The CO2 onshore storage terminal transports CO2 to the floating CO2 storage device at sea with an internal turret through a pipeline. After the floating CO2 storage device with an internal turret arrives at the target sea area, it transmits it to the CO2 offshore injection platform through the internal turret device, subsea pipeline and underwater riser, and injects it into the subsea CO2 storage site through the subsea wellhead; The operations included in step a or b or c are as follows: S1. Inject liquid CO2 into the storage tank. The storage tank includes a tank body (95) for storing liquid CO2 with a heat insulation layer. Discharge devices (92) and injection devices (91) with one-way valve bodies are respectively arranged on both sides of the tank body (95). The center of gravity of the tank body (95) is biased towards the side of the discharge device (92); A nitrogen generating device (94) is arranged inside the tank body (95) on the side of the injection device (91); The discharge device (92) includes a pressure-controlled relief device (96); S2. Transport the storage tank to the ocean storage area by ship; S3. Put the storage tank into seawater. Due to the center of gravity, the storage tank sinks in a vertical state, and the side of the discharge device (92) is at the bottom; S4. The pressure inside the storage tank increases. When it reaches the opening pressure of the relief device (96), the relief device (96) opens, and CO2 flows out to achieve pressure relief; S5. When the external seawater pressure reaches the opening pressure of the injection device (91) as the storage tank sinks, the injection device (91) opens, and seawater flows into the storage tank; S6. When the storage tank sinks to the CO2 storage depth, the injection device (91) and the discharge device (92) 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 (91) closes; S7. The nitrogen generating device (94) works to generate nitrogen. The storage tank discharges seawater, and the storage tank floats; The discharge device (92) closes; S8. The storage tank floats to the sea surface and is recycled again.

2. The CO2 offshore transfer and storage system according to claim 1, wherein The storage tank realizes that the center of gravity is biased towards the side of the discharge device (92) through fixed weights.

3. The CO2 offshore transfer and storage system according to claim 1, characterized in that, The storage tank is fixed with a satellite positioning device (93) for positioning during recovery.

4. The CO2 offshore transfer and storage system according to claim 1, characterized in that, The storage tank is provided with a position monitoring device for determining the depth of sinking of the storage tank; the injection device (91) and the discharge device (92) are respectively provided with remote control opening and closing devices for opening and closing when the storage tank is detected to be at the determined depth.

5. The CO2 offshore transfer and storage system according to claim 1, wherein The maximum allowable pressure of the storage tank is 30 bar.

6. The CO2 offshore transfer and storage system according to claim 1, characterized in that, The minimum CO2 storage depth in step S6 is 1000 m.

7. The CO2 offshore transfer and storage system according to any one of claims 1 to 6, characterized in that, When the CO2 in the pipeline is in a liquid state, the pressure range in the pipeline is 0.4 - 7.39 MPa; when the CO2 in the pipeline is in a supercritical state, the temperature in the pipeline > 31.3 °C and the pressure in the pipeline > 7.39 MPa; when the CO2 in the pipeline is in a gaseous state, the pressure range in the pipeline is 0 - 7.39 MPa; The CO2 carrier uses a type C tank for storage, and the CO2 storage pressure of the type C tank is 0.4 MPa - 2.1 MPa.

Images