Offshore floating carbon dioxide sequestration and methanol production apparatus and methods of use

Abstract

The application provides offshore floating carbon dioxide storage and methanol preparation equipment and a use method thereof, wherein a CO2 seabed storage and methanol preparation unit comprises a liquid CO2 receiving unit, a liquid CO2 storage unit, a CO2 feeding unit, a CO2 metering unit, a CO2 injection unit, a CO2 heating unit, a supercritical CO2 injection manifold unit, a hydrogen receiving and storage unit, a gas compression unit, a methanol synthesis unit, a methanol rectification and liquefaction unit, a liquid methanol storage unit, a nitrogen production unit and a liquid methanol delivery unit. The application not only realizes stable storage of supercritical CO2 in seabed abandoned oil fields, but also makes full use of "green hydrogen" produced by "abandoned wind and electricity" of offshore wind farms, realizes resource recycling of CO2 hydrogenation to prepare methanol, especially can be operated in abandoned oil and gas fields in different sea areas, has strong friendliness, flexibility and repeatability, and provides an effective application scheme for CO2 storage and recycling.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide sequestration and utilization, and more specifically, to equipment and methods for offshore floating carbon dioxide sequestration and methanol production. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS), as an emerging technology, is one of the most effective measures to mitigate the greenhouse effect and reduce CO2 concentration. Its core idea is to capture, store, or utilize CO2 emitted from industry. Currently, all existing technologies are for onshore CO2 storage, but these pose risks such as polluting groundwater and proximity to residential areas. Subsea storage, especially storage in abandoned offshore oil fields, offers the following advantages over onshore storage: seawater pressure and rock caps provide greater sealing and safety; offshore reservoirs suitable for carbon storage are widely distributed, with significant application potential and easier site selection; subsea storage is not only far from freshwater aquifers but also from residential areas, resulting in lower local risks and greater environmental friendliness; utilizing abandoned offshore oil fields for carbon storage can significantly reduce the overall costs of geological exploration and drilling. However, the key floating equipment for offshore CO2 storage still requires further development, hindering progress in offshore storage.

[0003] Meanwhile, the optimal CCUS solution goes beyond seabed sequestration; it aims to convert CO2 into resources and energy, generating economic benefits simultaneously. Methanol, as an important chemical raw material and energy source, is widely used in organic synthesis, pesticides, pharmaceuticals, coatings, automobiles, and defense industries. Currently, industrial methanol synthesis still relies on fossil fuels, primarily employing the catalytic conversion of syngas, where coal is gasified to produce methanol via syngas (CO + H2). Furthermore, offshore abandoned oil fields often have offshore wind farms, and the "green hydrogen" produced from abandoned wind and electricity at sea faces numerous storage and transportation challenges. Summary of the Invention

[0004] This invention provides equipment and methods for offshore floating carbon dioxide storage and methanol production, which solves the problems of existing technologies that all involve land-based CO2 storage, such as polluting groundwater and being located too close to residential areas.

[0005] To achieve the above objectives, the present invention provides equipment for offshore floating carbon dioxide storage and methanol production. The floating equipment comprises two parts: a CO2 seabed storage and methanol production system and a shipboard support system. The CO2 seabed storage and methanol production system includes a CO2 seabed storage unit and a methanol production unit. The CO2 seabed storage unit includes, in sequence, a liquid CO2 receiving unit, a liquid CO2 storage unit, a CO2 feeding unit, a CO2 metering unit, a CO2 injection unit, a CO2 heating unit, and a supercritical CO2 injection manifold unit.

[0006] The CO2 subsea storage unit receives liquid CO2 transported by a CO2 transport vessel through the liquid CO2 receiving unit and delivers it to the liquid CO2 storage unit for storage. The CO2 feeding unit pumps liquid CO2 from the liquid CO2 storage unit, which is then delivered to the CO2 injection unit via the CO2 metering unit. The CO2 metering unit provides feedback signals to control the discharge rate of the CO2 feeding unit. After being pressurized by the CO2 injection unit, the CO2 is heated by the CO2 heating unit to become supercritical CO2. The supercritical CO2 is then regulated and distributed through the injection manifold unit, entering the injection riser to achieve simultaneous injection and storage at the abandoned oilfield wellhead.

[0007] The methanol production unit includes, in sequence, a hydrogen receiving and storage unit, a gas compression unit, a methanol synthesis unit, a methanol distillation and liquefaction unit, a liquid methanol storage unit, a nitrogen production unit, and a liquid methanol export unit;

[0008] The methanol production unit receives and stores hydrogen through the hydrogen receiving and storage unit; and supplies CO2 through the liquid CO2 storage unit and the gas compression unit that compresses CO2 and hydrogen; simultaneously, excess CO2 at the outlet of the CO2 feeding unit serves as the CO2 feedstock for the gas compression unit; the hydrogen and CO2 feedstocks are pressurized to the methanol synthesis pressure by the gas compression unit and then transported to the methanol synthesis unit to produce crude methanol. The crude methanol then enters the methanol distillation and liquefaction unit for purification and liquefaction, and then enters the liquid methanol storage unit for storage; finally, it is unloaded onto a docked methanol transport ship via the liquid methanol export unit.

[0009] The floating equipment includes a second deck and a first deck arranged from top to bottom. The second deck, on its port side, is sequentially equipped with a CO2 feeding unit, a CO2 metering unit, a CO2 injection unit, a CO2 heating unit, and a supercritical CO2 injection manifold unit. A liquid CO2 receiving unit is located on the port side of the stern of the second deck and communicates with the CO2 feeding unit via a CO2 storage unit on the first deck. The second deck, on its starboard side, is sequentially equipped with a nitrogen generation unit, a hydrogen receiving and storage unit, a gas compression unit, a methanol synthesis unit, and a methanol distillation and liquefaction unit, and communicates with a liquid methanol export unit on the starboard side of the stern of the second deck via a liquid methanol storage unit on the first deck.

[0010] The marine support system includes a generator system for providing power; a cooling water system for providing cooling water; a fire protection system for providing fire protection; a CO2 cargo handling system for handling liquid cargo during operation of the liquid CO2 storage unit; a methanol cargo handling system for handling liquid cargo during operation of the liquid methanol storage unit; bow deck mooring equipment; and conventional marine systems.

[0011] Preferably, the liquid methanol storage unit includes a liquid methanol storage tank disposed on the starboard side of the first deck, and the CO2 storage unit includes a liquid CO2 storage tank disposed on the port side of the first deck.

[0012] Preferably, the liquid methanol storage tank and the liquid CO2 storage tank are arranged in a number that correspond one-to-one.

[0013] Preferably, the nitrogen generation unit provides nitrogen gas during the maintenance of the methanol storage unit to perform drying and inerting operations.

[0014] Preferably, the pressure of the CO2 injection unit is 7.38 to 20 MPa, and the temperature is -55 to 60°C.

[0015] Preferably, the pressure of the CO2 heating unit is 7.38–20 MPa and the temperature is 0–80 °C.

[0016] Preferably, the pressure of the supercritical CO2 injection manifold unit is 7.38–20 MPa, and the temperature is 31.4–80 °C.

[0017] Preferably, several ballast tanks filled with ballast water are symmetrically arranged on the outer sides of the port and starboard sides of the first deck 1.

[0018] Preferably, the bow deck mooring equipment is located on the first deck; the fire protection system includes a bow fire pump room located at the bow of the second deck; the generator system includes a bow power distribution room located on the first deck; and the marine conventional systems include a stern auxiliary equipment room, a stern pump room, a living area, and a seabed valve box.

[0019] This invention not only enables the stable storage of large quantities of supercritical CO2 in abandoned seabed oil fields, but also fully utilizes "green hydrogen" generated from abandoned wind and electricity in offshore wind farms to achieve the resource-based reuse of CO2 to produce methanol. In particular, it can be used for service operations in abandoned oil and gas fields in different sea areas, exhibiting strong friendliness, flexibility, and reusability. Therefore, this invention also provides an effective application solution for CO2 sequestration and reuse technology, and has significant application prospects. Attached Figure Description

[0020] Figure 1 This is a system flowchart of the floating equipment of the present invention;

[0021] Figure 2 This is a top view of the second deck of the floating equipment of the present invention;

[0022] Figure 3 This is a schematic diagram of the floating equipment structure of the present invention;

[0023] Figure 4 This is a top view of the first deck of the floating equipment of the present invention;

[0024] The components include: 1. First deck; 2. Second deck; 11. CO2 receiving unit; 12. CO2 storage unit; 13. CO2 feeding unit; 14. CO2 metering unit; 15. CO2 injection unit; 16. CO2 heating unit; 17. Supercritical CO2 injection manifold unit; 21. Nitrogen production unit; 22. Hydrogen receiving and storage unit; 23. Gas compression unit; 24. Methanol synthesis unit; 25. Methanol distillation and liquefaction unit; 26. Liquid methanol storage unit; 27. Liquid methanol export unit. 31. Generator system; 32. Cooling water system; 33. Fire protection system; 34. CO2 cargo handling system; 35. Methanol cargo handling system; 36. Marine conventional systems; 40. Living quarters; 50. Bow deck mooring equipment; 60. Bow auxiliary equipment room; 61. Bow power distribution room; 62. Bow fire pump room; 63. Stern main generator room; 64. Stern auxiliary equipment room; 65. Stern pump room; 70. Seafloor valve box; 80. Ballast tank; 121. Liquid CO2 storage tank; 261. Liquid methanol storage tank. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] As attached Figure 1 As shown, the present invention Figure 1 This is a system flowchart of the floating equipment. The floating equipment of this invention is divided into two parts: a CO2 seabed storage and methanol preparation system and a ship support system. The CO2 seabed storage and methanol preparation system includes a CO2 seabed storage unit and a methanol preparation unit. The CO2 seabed storage unit includes: a liquid CO2 receiving unit 11, a liquid CO2 storage unit 12, a CO2 feeding unit 13, a CO2 metering unit 14, a CO2 injection unit 15, a CO2 heating unit 16, and a supercritical CO2 injection manifold unit 17.

[0027] The specific process of the CO2 subsea storage unit is as follows: The liquid CO2 receiving unit 11 receives the liquid CO2 transported by the CO2 transport ship and delivers it to the liquid CO2 storage unit 12 for storage; the CO2 feeding unit 13 pumps liquid CO2 from the liquid CO2 storage unit 12 and feeds it to the CO2 injection unit 15. During this process, the CO2 metering unit 14 can control the discharge rate of the CO2 feeding unit 13 through feedback signals; after being pressurized by the liquid CO2 injection unit 15 and temperature regulated by the heating unit 16, it becomes supercritical CO2; finally, the supercritical CO2 is distributed by the injection manifold unit 17 and enters the injection riser, ultimately realizing the simultaneous injection and storage of abandoned oilfields from a single wellhead or multiple wellheads.

[0028] The design parameters of the supercritical CO2 injection and storage unit are as follows: the design pressure of the CO2 injection unit is 7.38 MPa to 20 MPa, and the design temperature is -55℃ to 60℃; the design pressure of the CO2 heating unit is 7.38 MPa to 20 MPa, and the design temperature is 0℃ to 80℃; the design pressure of the supercritical CO2 injection manifold unit is 7.38 MPa to 20 MPa, and the design temperature is 31.4℃ to 80℃. That is, the supercritical CO2 obtained by this invention has a pressure of 7.38 MPa to 20 MPa and a temperature of 31.4℃ to 80℃, and its density is close to that of a liquid and its viscosity is close to that of a gas.

[0029] The methanol production unit of the floating equipment of the present invention includes: a hydrogen receiving and storage unit 22, a gas compression unit 23, a methanol synthesis unit 24, a methanol distillation and liquefaction unit 25, a liquid methanol storage unit 26, a nitrogen production unit 21, and a liquid methanol export unit 27.

[0030] The specific process for methanol production using the floating equipment of this invention is as follows: A hydrogen receiving and storage unit 22 receives and stores "green hydrogen" generated from abandoned wind and electricity at offshore wind farms; a liquid CO2 storage unit 12 supplies CO2 to a gas compression unit 23 for compressing CO2 and hydrogen. Additionally, excess CO2 at the outlet of the CO2 feeding unit 13 also serves as a CO2 feedstock for the gas compression unit 23; after being pressurized to the required pressure for methanol synthesis by the gas compression unit 23, the hydrogen and CO2 feedstocks are transported to the methanol synthesis unit 24 for crude methanol production. The crude methanol then enters the methanol distillation and liquefaction unit 25 for purification and liquefaction, before entering the liquid methanol storage unit 26 for storage; finally, it is unloaded onto a docked methanol transport ship via the liquid methanol export unit 27. A nitrogen generation unit 21 provides nitrogen supply during methanol storage unit maintenance for drying and inerting operations.

[0031] Details are as follows (attached) Figure 2As shown in the top view of the second deck 2 of the floating equipment of the present invention, the CO2 seabed storage unit of the floating equipment includes a CO2 feeding unit 13, a CO2 metering unit 14, a CO2 injection unit 15, a CO2 heating unit 16, and a supercritical CO2 injection manifold unit 17 connected in sequence and located on the port side of the second deck 2; the methanol production unit of the floating equipment includes a nitrogen production unit 21 and a hydrogen storage unit 22, a gas compression unit 23, a methanol synthesis unit 24, a methanol distillation and liquefaction unit 25, a liquid methanol storage unit 26, a liquid methanol export unit 27, a nitrogen production unit 21, and a hydrogen receiving unit connected in sequence. The storage unit 22, gas compression unit 23, methanol synthesis unit 24, and methanol distillation and liquefaction unit 25 are located on the starboard side of the second deck 2; the liquid CO2 receiving unit 11 is located on the port side of the stern of the second deck 2 of the floating equipment and is connected to the CO2 feeding unit 13 through the CO2 storage unit 12 provided on the first deck 1; the liquid methanol export unit 27 is located on the starboard side of the stern of the second deck 2 of the floating equipment; in addition, the second deck 2 is also equipped with a living area 40 for the daily living area of ​​the staff; the second deck 2 is also equipped with bow deck mooring equipment 50 and a pipe gallery area for the mooring equipment and pipelines of the floating equipment.

[0032] Details are as attached Figure 3 As shown in the schematic diagram of the floating equipment of the present invention, it includes a second deck 2 and a first deck 1 arranged from top to bottom, a nitrogen generation unit 21 located on the starboard side of the second deck 2, and a hydrogen receiving and storage unit 22, a gas compression unit 23, a methanol synthesis unit 24, and a methanol distillation and liquefaction unit 25 connected in sequence. The unit is connected to a liquid methanol export unit 27 on the starboard side of the stern of the second deck 2 via a liquid methanol storage unit 26 on the first deck 1. The first deck 1 has a bow auxiliary equipment room 60 and a bow equipment room 60. Electrical room 61, bow fire pump room 62 at the bow of the second deck 2, and stern auxiliary equipment room 64, stern pump room 65 and seabed valve box 70 at the stern of the first deck 1 are provided. The bow electrical room 61 is located on the first deck 1, and the bow deck mooring equipment 50 and bow fire pump room 62 are located on the second deck 2. Ballast tank 80, liquid methanol storage unit 26 and its included liquid methanol storage tank 261, and CO2 storage unit 12 and its included liquid CO2 storage tank 121 are located on the first deck 1.

[0033] The floating equipment also provides auxiliary functions for the marine support systems required for CO2 marine storage and methanol production: the generator system 31 provides power to the entire floating equipment; the cooling water system 32 provides cooling water to all equipment units on the ship that require cooling; the fire protection system 33 provides fire protection for the entire ship; the CO2 cargo handling system 34 provides liquid cargo handling function when the liquid CO2 storage unit 12 is operating; the methanol cargo handling system 35 provides liquid cargo handling function when the liquid methanol storage unit 26 is operating; and conventional marine systems, such as ballast water, are used to ensure the safe and normal operation of the floating equipment's hull.

[0034] Details are as attached Figure 4 As shown, this is a top view of the first deck 1 of the floating equipment of the present invention. The first deck 1 is provided with a stern main generator room 63 and a bow power distribution room 61. The port side of the first deck 1 is provided with a liquid methanol storage unit 26 and a plurality of liquid methanol storage tanks 261 therein. The starboard side of the first deck 1 is provided with a CO2 storage unit 12 and a plurality of liquid CO2 storage tanks 121 therein, that is, the plurality of liquid methanol storage tanks 261 and the plurality of liquid CO2 storage tanks 121 are symmetrically arranged on the left and right sides. A plurality of ballast tanks 80 are symmetrically arranged on the port and starboard sides of the first deck 1.

[0035] This invention not only enables the large-scale and stable storage of supercritical CO2 in abandoned seabed oil fields, but also makes full use of the "green hydrogen" produced by "wasted wind and electricity" in offshore wind farms, realizing the resource utilization of CO2 in the form of methanol through hydrogenation. In particular, it can be used for service operations in abandoned oil and gas fields in different sea areas, and has strong friendliness, flexibility and reusability.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An equipment for offshore floating carbon dioxide sequestration and methanol production, characterized in that, It includes two parts: a CO2 seabed storage and methanol preparation system and a marine support system; the CO2 seabed storage and methanol preparation system includes a CO2 seabed storage unit and a methanol preparation unit; the CO2 seabed storage unit includes: a liquid CO2 receiving unit (11), a liquid CO2 storage unit (12), a CO2 feeding unit (13), a CO2 metering unit (14), a CO2 injection unit (15), a CO2 heating unit (16), and a supercritical CO2 injection manifold unit (17) connected in sequence; The CO2 seabed storage unit receives liquid CO2 transported by the CO2 transport ship through the liquid CO2 receiving unit (11) and delivers it to the liquid CO2 storage unit (12) for storage. The CO2 feeding unit (13) pumps liquid CO2 from the liquid CO2 storage unit (12) and delivers it to the CO2 injection unit (15) through the CO2 metering unit (14). The CO2 metering unit (14) sends a feedback signal to control the discharge rate of the CO2 feeding unit (13). After being pressurized by the CO2 injection unit (15), the CO2 is adjusted to become supercritical CO2 through the CO2 heating unit (16). The supercritical CO2 is then distributed through the supercritical CO2 injection manifold unit (17) and enters the injection riser to achieve injection and storage of abandoned oilfield wellheads. The methanol production unit includes: a hydrogen receiving and storage unit (22), a gas compression unit (23), a methanol synthesis unit (24), a methanol distillation and liquefaction unit (25), a liquid methanol storage unit (26), a nitrogen production unit (21), and a liquid methanol export unit (27) connected in sequence. The methanol production unit receives and stores hydrogen through the hydrogen receiving and storage unit (22), which utilizes wind and electricity waste from offshore wind farms. CO2 is then transported through the liquid CO2 storage unit (12) and the gas compression unit (23) that compresses CO2 and hydrogen from the liquid CO2 storage unit (12). Simultaneously, excess CO2 at the outlet of the CO2 feeding unit (13) serves as the CO2 raw material source for the gas compression unit (23). After the hydrogen and CO2 raw materials are pressurized to the methanol synthesis pressure by the gas compression unit (23), they are transported to the methanol synthesis unit (24) to produce crude methanol. The crude methanol then enters the methanol distillation and liquefaction unit (25) for purification and liquefaction, and then enters the liquid methanol storage unit (26) for storage. Finally, it is unloaded into a berthed methanol transport ship via the liquid methanol export unit (27). The floating equipment includes a second deck (2) and a first deck (1) arranged from top to bottom. On the port side of the second deck (2), a CO2 feeding unit (13), a CO2 metering unit (14), a CO2 injection unit (15), a CO2 heating unit (16), and a supercritical CO2 injection manifold unit (17) are arranged in sequence. The liquid CO2 receiving unit (11) is located on the port side of the stern of the second deck (2) and is connected to the CO2 feeding unit (13) through the liquid CO2 storage unit (12) provided on the first deck (1). On the starboard side of the second deck (2), a nitrogen generating unit (21) and a hydrogen receiving and storage unit (22) are arranged in sequence. Gas compression unit (23), methanol synthesis unit (24), methanol distillation and liquefaction unit (25), wherein the methanol distillation and liquefaction unit (25) is connected to the liquid methanol export unit (27) on the starboard side of the stern of the second deck (2) via the liquid methanol storage unit (26) on the first deck (1); The marine support system includes a generator system (31) providing power; a cooling water system (32) providing cooling water; a fire protection system (33) providing fire protection; a CO2 cargo handling system (34) providing liquid cargo handling for the operation of the liquid CO2 storage unit (12); a methanol cargo handling system (35) providing liquid cargo handling for the operation of the liquid methanol storage unit (26); and bow deck mooring equipment (50). The supercritical CO2 is CO2 with a pressure of 7.38–20 MPa and a temperature of 31.4–80 °C.

2. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The liquid methanol storage unit (26) includes a liquid methanol storage tank (261) disposed on the starboard side of the first deck (1), and the liquid CO2 storage unit (12) includes a liquid CO2 storage tank (121) disposed on the port side of the first deck (1).

3. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 2, characterized in that, The liquid methanol storage tank (261) and the liquid CO2 storage tank (121) are of several quantities and are arranged in a one-to-one correspondence.

4. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The nitrogen generation unit (21) provides nitrogen supply during the maintenance of the methanol storage unit (26) to perform drying and inerting operations.

5. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The pressure of the CO2 injection unit (15) is 7.38 to 20 MPa, and the temperature is -55 to 60°C.

6. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The CO2 heating unit (16) has a pressure of 7.38-20 MPa and a temperature of 0-80°C.

7. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The pressure of the supercritical CO2 injection manifold unit (17) is 7.38-20 MPa and the temperature is 31.4-80℃.

8. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, Several ballast tanks (80) filled with ballast water are symmetrically arranged on the port and starboard sides of the first deck (1).

9. The equipment for offshore floating carbon dioxide storage and methanol production according to claim 1, characterized in that, The bow deck mooring equipment (50) is located on the first deck (1); the fire protection system (33) includes a bow fire pump room (62) located at the bow of the second deck (2); the generator system (31) includes a bow power distribution room (61) located on the first deck (1).

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