A method for simultaneous offshore crude oil production and carbon dioxide sequestration

Abstract

A method for offshore crude oil production and carbon dioxide storage simultaneously, a crude oil production module collects crude oil in a subsea oil well and sends it to a crude oil separation module, when the production of an oil well is completed, the oil well will be used as a carbon dioxide storage well. A liquid carbon dioxide receiving module receives liquid carbon dioxide transported by a liquid carbon dioxide pump from a liquid carbon dioxide transport ship, and sends the gas-liquid mixed carbon dioxide to a gas-liquid mixed carbon dioxide pressurizing module for pressurizing and heating operation to form supercritical carbon dioxide, and sends the supercritical carbon dioxide to a supercritical carbon dioxide injection module for distribution of the supercritical carbon dioxide and injection into a subsea carbon dioxide storage well. The present application realizes the simultaneous operation of crude oil production and carbon storage, maximizes the use of subsea oil wells and related pipelines, improves the economy of offshore carbon storage operation, avoids the risk of secondary drilling of abandoned oil wells, and improves the safety of offshore carbon storage operation.

Description

Technical Field

[0001] This invention belongs to the field of marine vessel design and construction, and specifically relates to a method for simultaneously carrying out offshore crude oil production and carbon dioxide sequestration. Background Technology

[0002] Offshore carbon sequestration has the following advantages: seawater pressure and rock caps provide greater sealing and security; seabed reservoirs suitable for carbon sequestration are widely distributed, with great application potential and easy selection of sequestration sites; seabed storage is not only far from freshwater aquifers but also far from residential areas, resulting in lower local risks and greater environmental friendliness; utilizing abandoned offshore oil fields for carbon sequestration can significantly reduce the overall costs of geological exploration and drilling.

[0003] Currently, research on offshore CCUS focuses more on carbon sequestration processes and methods. Patent CN219655826U discloses a co-injection and extraction system for carbon dioxide sequestration in seabed saline water layers; patent CN114278257A discloses a device and method for synchronizing offshore oilfield development and supercritical carbon dioxide sequestration, both of which are innovations in CCUS technology.

[0004] Research on offshore CCUS equipment is still in its early stages. Patent CN116480934A discloses an offshore floating carbon dioxide storage and methanol production equipment, which mentions storing carbon dioxide in old oil fields, but does not mention how to open up old oil fields that have been abandoned and sealed.

[0005] Offshore carbon dioxide sequestration in aging oil fields requires re-drilling wells in these already sealed areas, significantly increasing the cost of carbon sequestration. Furthermore, aging oil fields exhibit instability in terms of pressure, composition, and geology; reopening these wells could trigger accidents such as wellhead collapse or well fluid (gas) eruptions.

[0006] The safest and most ideal method for offshore carbon dioxide sequestration is to simultaneously extract and store carbon dioxide in offshore oil and gas fields, with offshore oil and gas extraction and carbon dioxide sequestration complementing and proceeding synchronously. Currently, there are no patents disclosing floating devices with this type of operation mode. Summary of the Invention

[0007] To address the above problems, this invention provides a method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration, the technical solution of which is as follows:

[0008] A method for simultaneously producing crude oil and storing carbon dioxide at sea, wherein multiple modules are installed above the main deck of the ship, and multiple crude oil storage tanks and multiple liquid carbon dioxide storage tanks are installed below the main deck of the ship, with the multiple crude oil storage tanks and multiple liquid carbon dioxide storage tanks alternately arranged along the length and width of the ship.

[0009] The crude oil extraction module collects crude oil from the subsea well via an external riser pipeline and sends it to the crude oil separation module. When the pressure inside the subsea well is insufficient, the crude oil extraction module injects supercritical carbon dioxide into the well to increase the pressure. The crude oil separation module performs preliminary physical separation on the extracted crude oil and sends the physically separated crude oil to the crude oil purification module. The crude oil purification module injects chemical reagents into the crude oil to remove harmful liquid impurities, thereby obtaining qualified crude oil which is sent to the crude oil testing and diversion module. Crude oil that passes the test by the crude oil testing and diversion module enters the crude oil storage tank, while unqualified crude oil is returned to the crude oil purification module for further purification. When the extraction of a certain oil well is completed, that oil well will be used as a carbon dioxide storage well.

[0010] The liquid carbon dioxide receiving module receives liquid carbon dioxide transported by the liquid carbon dioxide transport ship via a liquid carbon dioxide pump. After receiving, the liquid carbon dioxide is first pressurized to 12 MPa. After pressurization, the liquid carbon dioxide is distributed to each liquid carbon dioxide storage tank through pipe valves. The liquid carbon dioxide pumping module is connected to the liquid carbon dioxide storage tank and pumps the liquid carbon dioxide out of the storage tank, pressurizes it to 12 MPa, and then sends it to the liquid carbon dioxide heating module for heating to 31.26°C. While heating in the liquid carbon dioxide heating module, the pressure is depressurized to 8 MPa. At this point, the carbon dioxide is in a gas-liquid mixture state. The gas-liquid mixture is then sent to the gas-liquid mixture carbon dioxide pressurization module for pressurization and heating, so that the carbon dioxide pressure reaches 20 MPa and the temperature reaches 60°C, forming supercritical carbon dioxide. This supercritical carbon dioxide is then sent to the supercritical carbon dioxide injection module, which distributes the supercritical carbon dioxide and injects it into the seabed carbon dioxide storage well.

[0011] Furthermore, in the aforementioned method for simultaneously producing crude oil and storing carbon dioxide at sea, the crude oil extraction module, crude oil separation module, crude oil purification module, crude oil detection and diversion module, and crude oil manifold valve group module are located above the main deck and are sequentially connected and arranged along the length of the hull.

[0012] The liquid carbon dioxide receiving module, liquid carbon dioxide pumping module, liquid carbon dioxide heating module, gas-liquid mixed carbon dioxide pressurization module, and supercritical carbon dioxide injection module are located above the main deck and are connected and arranged sequentially along the length of the hull.

[0013] The ship has a living quarters on the main deck at the stern and a forecastle on the main deck at the bow. Behind the living quarters are crude oil output devices and crude oil metering skids. The crude oil output devices are connected to the transport system of the crude oil tanker.

[0014] Generator modules are installed between the living quarters and the crude oil extraction module, and between the living quarters and the liquid carbon dioxide receiving module.

[0015] Furthermore, in the aforementioned method of simultaneously producing and storing crude oil at sea, qualified crude oil is further packaged into various storage tanks via crude oil manifold valves.

[0016] Furthermore, in the above-mentioned method of simultaneously producing offshore crude oil and storing carbon dioxide, the crude oil separation module separates the associated gases in the crude oil through settling and sedimentation. The toxic gases and carbon dioxide in the associated gas are reinjected into the oil well, while the non-toxic gases in the associated gas are burned or stored as fuel.

[0017] Furthermore, in the aforementioned method of simultaneously producing crude oil and storing carbon dioxide at sea, a liquid carbon dioxide input device is installed at the stern of the ship, and the liquid carbon dioxide receiving module is connected to the unloading device of the berthed carbon dioxide transport ship through the liquid carbon dioxide input device.

[0018] Furthermore, in the aforementioned method for simultaneously producing offshore crude oil and storing carbon dioxide, the chemical reagents within the crude oil purification module are...

[0019] The aforementioned method for simultaneously producing crude oil and storing carbon dioxide at sea further involves burning a combustible, non-toxic gas within the associated gas, which is natural gas.

[0020] Furthermore, in the aforementioned method of simultaneously conducting offshore crude oil production and carbon dioxide sequestration, the liquid carbon dioxide storage tank is a pressure tank, and the pressure inside the tank must not be less than 7.3 MPa at any time, and is 10 MPa under normal conditions.

[0021] Furthermore, in the aforementioned method of simultaneously producing crude oil and storing carbon dioxide at sea, the pipelines and valves for the inlet and outlet of liquid carbon dioxide in the liquid carbon dioxide storage tank are installed on the main deck, and the outer surface of the pipelines and valves is wrapped with a thermal insulation layer.

[0022] Furthermore, in the aforementioned method of simultaneously producing offshore crude oil and storing carbon dioxide, the temperature rise of the liquid carbon dioxide in the pipelines and valves must not exceed 0.3°C.

[0023] The beneficial effects of this invention are:

[0024] 1. It enables the simultaneous development of crude oil extraction and carbon sequestration, maximizing the utilization of subsea oil wells and related pipelines, and improving the economic efficiency of offshore carbon sequestration operations.

[0025] 2. It avoids the risks associated with secondary drilling of abandoned oil wells and improves the safety of offshore carbon sequestration operations.

[0026] 3. During crude oil extraction, carbon dioxide can be injected into the oil field to pressurize it, thereby assisting crude oil extraction while injecting carbon dioxide. This allows crude oil extraction and carbon dioxide injection operations to complement each other, further improving the economic efficiency of the entire unit. Attached Figure Description

[0027] Figure 1 This is a top view of the upper part of the main deck of the present invention;

[0028] Figure 2 This is a top view of the lower part of the main deck of the present invention;

[0029] Figure 3 This is a side view of the present invention;

[0030] Figure 4 This is a flowchart of the operation process of this invention;

[0031] Among them: 111-Crude oil storage tank, 121-Crude oil output device, 122-Crude oil metering skid, 13-Crude oil extraction module, 14-Crude oil separation module, 15-Crude oil purification module, 16-Crude oil detection and diversion module, 17-Crude oil manifold valve group module, 211-Liquid carbon dioxide storage tank, 221-Liquid carbon dioxide input device, 222-Liquid carbon dioxide metering skid, 23-Liquid carbon dioxide receiving module, 24-Liquid carbon dioxide pumping module, 25-Liquid carbon dioxide heating module, 26-Gas-liquid mixed carbon dioxide pressurization module, 27-Supercritical carbon dioxide injection module, 311-Ballast tank, 321-Sternship stern machinery space, 322-Sternship bow machinery space, 331-Multi-point mooring device, 34-Living quarters, 35-Forecastle, 361-Generator module, 37-Outside riser, A-Main deck, B-Hull. Detailed Implementation

[0032] The invention will be further described with reference to the accompanying drawings.

[0033] A method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration, such as Figures 1-4 As shown, it possesses the functions of offshore crude oil extraction, storage, and export, as well as offshore liquid carbon dioxide receiving and sequestration. While extracting each oil well, supercritical carbon dioxide is injected into the well according to the degree of crude oil extraction, achieving permanent sequestration of carbon dioxide within the offshore oil and gas field.

[0034] The crude oil storage tank is located within the ship's hull, intersecting the liquid carbon dioxide storage tank on both sides. Piping and valves for crude oil entering and exiting the crude oil storage tank are located on the deck, while pumps, specifically deep-sea submersible pumps, are located inside the tank. Similarly, piping and valves for liquid carbon dioxide entering and exiting the liquid carbon dioxide storage tank are located on the deck and are insulated to maintain the temperature rise of the liquid carbon dioxide within the pipes within a controllable range, not exceeding 0.3°C. Pumps, specifically cryogenic deep-sea submersible pumps, are located inside the tank.

[0035] As crude oil continuously enters the crude oil storage tanks in the hull from the oil field, and carbon dioxide continuously leaves the carbon dioxide storage tanks in the hull and is injected into the oil wells, this in-and-out operation mode ensures the weight balance of the hull to the greatest extent possible, preventing significant listing.

[0036] Each crude oil storage tank is equipped with a dedicated oil pump used to deliver crude oil to the crude oil output device via a crude oil metering skid pump. The oil pump is a deep-sea submersible pump, which is centrally controlled. Its flow rate must take into account not only the crude oil output but also the liquid carbon dioxide sequestration rate, ensuring that the weight of the output crude oil and the liquid carbon dioxide injected into the sequestration well are as similar as possible to avoid platform tilting.

[0037] The crude oil export unit is located at the stern of the ship. Crude oil from the storage tanks is pumped to the export unit, where it is unloaded onto the crude oil carrier for transport. The export unit is equipped with a hose, at least 200 meters long, used to connect the ship to the receiving vessel.

[0038] The crude oil metering skid is located between the crude oil output unit and the crude oil storage tank. It is used to measure the amount of crude oil unloaded onto the crude oil tanker through the crude oil output unit, thereby enabling metering and billing.

[0039] The crude oil extraction module is responsible for extracting crude oil. Crude oil from the subsea well is collected and brought to the device of this invention via crude oil pipelines on the outboard riser. When the well pressure is insufficient, the crude oil extraction module needs to inject chemicals into the well to increase the pressure. The chemicals are primarily supercritical carbon dioxide, and the selection of the injected medium is achieved through different medium pipelines and control valves within the crude oil extraction module.

[0040] Furthermore, the crude oil extraction module can control the extraction progress of different oil wells based on the conditions of the oil wells corresponding to different crude oil pipelines. When the extraction of a certain oil well is completed, that oil well will be used as a carbon dioxide storage well. The oil production pipeline will be closed by opening and closing valves, while the chemical injection pipeline will remain open to balance the pressure. The carbon dioxide injection pipeline will then begin to inject a large amount of supercritical carbon dioxide into the well for storage.

[0041] The crude oil separation module performs preliminary physical separation on the crude oil extracted by the crude oil extraction module. This is primarily achieved through settling and sedimentation to separate associated gases. Toxic gases and carbon dioxide from the associated gases are then reinjected into the well. Combustible gases (such as natural gas) are burned or stored as fuel, while non-combustible gases (such as nitrogen) are vented. The separated liquid crude oil then enters the crude oil purification module.

[0042] The crude oil purification module receives crude oil provided by the crude oil separation module and unqualified crude oil screened out by the crude oil detection and diversion module. It performs impurity removal and purification operations on the crude oil by adding chemical reagents to remove harmful liquid impurities in the crude oil, thereby obtaining qualified crude oil.

[0043] The crude oil detection and diversion module is responsible for detecting the crude oil delivered by the crude oil purification module, sending qualified crude oil to the crude oil manifold valve module, and returning unqualified crude oil to the crude oil purification module for further purification.

[0044] The crude oil manifold module receives qualified crude oil from the crude oil detection and diversion module and diverts it to various crude oil storage tanks for storage according to the actual situation. The diversion principle first considers keeping one crude oil storage tank as full as possible to avoid crude oil sloshing within the tank. Then, considering the weight distribution at the beginning and end, oil needs to be injected alternately into the beginning and end crude oil storage tanks in the following order: crude oil storage tank, crude oil storage tank, crude oil storage tank, crude oil storage tank, crude oil storage tank, crude oil storage tank.

[0045] The liquid carbon dioxide storage tank is located within the hull and is arranged diagonally to the crude oil storage tank. As liquid carbon dioxide is continuously discharged from the liquid carbon dioxide storage tank and crude oil is continuously fed into the crude oil storage tank, this diagonal arrangement helps to maintain the ship's weight balance and prevents significant listing.

[0046] The liquid carbon dioxide storage chamber is a pressure chamber, and the internal pressure must not be less than 7.3 MPa at any time, and should be maintained at around 10 MPa under normal conditions.

[0047] The liquid carbon dioxide input device can be connected to the unloading device of a berthed carbon dioxide carrier to receive liquid carbon dioxide transported by the carrier and pump it to the liquid carbon dioxide receiving module.

[0048] The liquid carbon dioxide metering skid is located between the liquid carbon dioxide input device and the liquid carbon dioxide receiving module. It is used to measure the received liquid carbon dioxide and serve as the basis for charging for the storage of this carbon dioxide.

[0049] The liquid carbon dioxide receiving module receives liquid carbon dioxide supplied by the liquid carbon dioxide input device and metered by the liquid carbon dioxide metering skid. Upon receipt, the liquid carbon dioxide is first pressurized to 12 MPa to compensate for pressure losses in the pipeline. This also provides a margin for pressure loss during the pipeline journey from the receiving module to the storage chamber, ensuring the carbon dioxide remains liquid and does not vaporize upon entering the storage chamber.

[0050] The liquid carbon dioxide receiving module controls the distribution of liquid carbon dioxide to each liquid carbon dioxide storage tank via pipe valves. When adding liquid carbon dioxide to the storage tanks, each tank should be filled first to avoid sloshing. Then, liquid carbon dioxide is added alternately from the beginning to the end to balance the weight distribution. The sequence is: liquid carbon dioxide storage tank, liquid carbon dioxide storage tank, liquid carbon dioxide storage tank, liquid carbon dioxide storage tank, liquid carbon dioxide storage tank, liquid carbon dioxide storage tank.

[0051] The liquid carbon dioxide pumping module is connected to the liquid carbon dioxide storage tank, pumping liquid carbon dioxide out of the tank and pressurizing it to 12 MPa to compensate for pressure losses in the pipelines and valves, while ensuring that the liquid carbon dioxide does not vaporize due to pressure drop during subsequent pipeline transportation. The liquid carbon dioxide pumping module then delivers the liquid carbon dioxide to the liquid carbon dioxide heating module.

[0052] The liquid carbon dioxide heating module receives liquid carbon dioxide from the liquid carbon dioxide pump module and heats it to bring the liquid carbon dioxide in the pipeline to the required supercritical carbon dioxide temperature of 31.26℃. This temperature is also the highest temperature at which carbon dioxide can remain liquid under a pressure of 12MPa. Heating is achieved through heating resistance wires wound around the outside of the pipeline. The heating resistance wires should be evenly distributed to avoid localized overheating. During the heating process, a small amount of liquid carbon dioxide inevitably vaporizes, so the carbon dioxide is in a gas-liquid mixed state at this stage. While heating, the liquid carbon dioxide heating module simultaneously reduces the carbon dioxide pressure to prevent an increase in pressure, ultimately reducing the pressure evenly to 8MPa. The carbon dioxide exiting the liquid carbon dioxide module is in a gas-liquid mixed state, with a temperature of 31.26℃ and a pressure of 8MPa.

[0053] The gas-liquid mixed carbon dioxide pressurization module receives the gas-liquid mixed carbon dioxide from the liquid carbon dioxide heating module, pressurizes it to a pressure of 20 MPa, and simultaneously heats it to a temperature of 60°C. At this point, the carbon dioxide enters a supercritical state, which is between a gaseous and a liquid state.

[0054] The supercritical carbon dioxide injection module receives supercritical carbon dioxide from the gas-liquid mixed carbon dioxide pressurization module and distributes it through pipelines and valves, injecting it into subsea oil wells. It can be injected as an enhancement agent into wells currently in production to balance well pressure and facilitate crude oil extraction. It can also be injected into wells that have already been depleted.

[0055] Ballast tanks are used by the device of this invention to adjust the buoyancy. Their number should be minimized while still being sufficient to adjust the buoyancy of the ship under various operating conditions, so as to reduce the amount of piping, valves, and tank walls used and reduce the empty ship weight. The stern engine room houses a generator room, pump room, air conditioning room, fan room, machine repair shop, auxiliary equipment room, and fire pump room, providing power, ventilation, power, and fire-fighting auxiliary functions for the device of this invention. The bow engine room houses a fire pump room and warehouse, providing fire-fighting auxiliary functions for the device of this invention. The multi-point mooring device includes an anchor chain lifting device, chain stopper, and chain guide, anchoring the device in a fixed position. The living quarters provide personnel living quarters and supporting facilities such as a restaurant, kitchen, and laundry room. There are two generator modules, providing power supply services for the crude oil production, storage, and offloading module and the carbon dioxide storage module, respectively. The outboard risers are located on one side of the device of this invention, and their number is determined according to the number of subsea wells. In principle, each oil well should have at least three risers: a crude oil production riser, a chemical injection riser, and a supercritical carbon dioxide injection riser. In addition, there should be umbilical cable protection pipes for powering related subsea equipment, usually no less than 60. After the risers are connected, crude oil production operations begin, and carbon dioxide storage operations can be carried out simultaneously with crude oil production operations.

Claims

1. A method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration, characterized in that, Multiple modules are installed above the main deck of the ship, and multiple crude oil storage tanks and multiple liquid carbon dioxide storage tanks are installed below the main deck of the ship. The multiple crude oil storage tanks and multiple liquid carbon dioxide storage tanks are arranged alternately along the length and width of the ship. Each crude oil storage tank is equipped with a dedicated oil pump, which is a deep-sea submersible pump. It is uniformly controlled by a central control system to ensure that the weight of the crude oil output and the liquid carbon dioxide injected into the sealing well are the same. The crude oil extraction module collects crude oil from the subsea well via an external riser pipeline and sends it to the crude oil separation module. When the pressure inside the subsea well is insufficient, the crude oil extraction module injects supercritical carbon dioxide into the well to increase the pressure. The crude oil separation module performs preliminary physical separation on the extracted crude oil and sends the physically separated crude oil to the crude oil purification module. The crude oil purification module adds chemical reagents to the crude oil to remove harmful liquid impurities, thereby obtaining qualified crude oil which is sent to the crude oil testing and diversion module. Crude oil that passes the test by the crude oil testing and diversion module enters the crude oil storage tank, while unqualified crude oil is returned to the crude oil purification module for further purification. When the extraction of a certain oil well is completed, that oil well will be used as a carbon dioxide storage well. The liquid carbon dioxide receiving module receives liquid carbon dioxide transported by the liquid carbon dioxide transport ship via a liquid carbon dioxide pump. After receiving, the liquid carbon dioxide is first pressurized to 12 MPa. After pressurization, the liquid carbon dioxide is distributed to each liquid carbon dioxide storage tank through pipe valves. The liquid carbon dioxide pumping module is connected to the liquid carbon dioxide storage tank and pumps the liquid carbon dioxide out of the storage tank, pressurizes it to 12 MPa, and then sends it to the liquid carbon dioxide heating module for heating to 31.26°C. While heating in the liquid carbon dioxide heating module, the pressure is depressurized to 8 MPa. At this point, the carbon dioxide is in a gas-liquid mixture state. The gas-liquid mixture is then sent to the gas-liquid mixture carbon dioxide pressurization module for pressurization and heating, so that the carbon dioxide pressure reaches 20 MPa and the temperature reaches 60°C, forming supercritical carbon dioxide. This supercritical carbon dioxide is then sent to the supercritical carbon dioxide injection module, which distributes the supercritical carbon dioxide and injects it into the seabed carbon dioxide storage well.

2. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, The crude oil extraction module, crude oil separation module, crude oil purification module, crude oil detection and diversion module, and crude oil manifold valve assembly module are located above the main deck and are connected and arranged sequentially along the length of the hull. The liquid carbon dioxide receiving module, liquid carbon dioxide pumping module, liquid carbon dioxide heating module, gas-liquid mixed carbon dioxide pressurization module, and supercritical carbon dioxide injection module are located above the main deck and are connected and arranged sequentially along the length of the hull. The ship has a living quarters on the main deck at the stern and a forecastle on the main deck at the bow. Behind the living quarters are crude oil output devices and crude oil metering skids. The crude oil output devices are connected to the transport system of the crude oil tanker. Generator modules are installed between the living quarters and the crude oil extraction module, and between the living quarters and the liquid carbon dioxide receiving module.

3. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, Qualified crude oil is packaged into various storage tanks via crude oil manifold valves.

4. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, The crude oil separation module separates associated gases from crude oil through settling and sedimentation. Toxic gases and carbon dioxide in the associated gas are reinjected into the oil well, while non-toxic gases in the associated gas are burned or stored as fuel.

5. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, A liquid carbon dioxide input device is installed at the stern of the ship. The liquid carbon dioxide receiving module is connected to the unloading device of the berthed carbon dioxide transport ship through the liquid carbon dioxide input device.

6. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 4, characterized in that, The combustible, non-toxic gas in the associated gas is burned; the combustible, non-toxic gas is natural gas.

7. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, The liquid carbon dioxide storage chamber is a pressure chamber, and the internal pressure must not be less than 7.3 MPa at any time, and is 10 MPa under normal conditions.

8. The method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 1, characterized in that, The pipes and valves for the liquid carbon dioxide to enter and exit the liquid carbon dioxide storage tank are located on the main deck, and the outer surface of the pipes and valves is covered with a thermal insulation layer.

9. A method for simultaneously conducting offshore crude oil production and carbon dioxide sequestration according to claim 8, characterized in that, The temperature rise of liquid carbon dioxide in pipelines and valves shall not exceed 0.3℃.

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