LNG liquid tank filling device of LNG transport ship

Abstract

The invention discloses an LNG liquid tank filling device of an LNG transport ship, and relates to the technical field of LNG transport, and the LNG liquid tank filling device is characterized by comprising a filling tank car, a nitrogen storage tank, a liquid tank and a flare tower, the filling tank car is connected with the LNG storage tank, and the end, away from the filling tank car, of the LNG storage tank is connected with a drying inerting system and a replacement system; the drying and inerting system is connected between the LNG storage tank and the liquid tank, the end, away from the drying and inerting system, of the liquid tank is connected with the flare tower, one end of the nitrogen storage tank is connected to the drying and inerting system, the other end of the nitrogen storage tank is connected to the replacement system, and a pre-cooling system is further connected between the liquid tank and the replacement system. The system is energy-saving, environment-friendly, safe and effective in LNG liquid tank filling.

Description

Technical Field

[0001] The invention belongs to the technical field of LNG transportation, and in particular relates to a formula of an LNG tank filling device for an LNG transport ship. Background Art

[0002] In recent years, as China's demand for clean energy increases, LNG has rapidly become popular in China as an environmentally friendly fuel. This trend has led to the rapid development of the LNG tank market, with an annual growth rate of more than 10%, making China's market size among the top in the world. On the technical level, domestic companies have independently developed LNG tanks that meet high international standards in storage capacity, safety and insulation performance. It is worth noting that some Chinese companies have successfully mastered the design and manufacturing technology of large LNG tanks, which is crucial to the country's energy security and clean energy supply.

[0003] The trend of liquefied natural gas as a marine fuel is becoming increasingly obvious. This trend has driven the development of LNG bunkering ships and the use of LNG in ports. The design quality of the liquid tank of the LNG bunkering ship is directly related to the overall performance, economic benefits and safety level of the ship. Taking the catamaran as an example, a C-type tank evaluation system containing four evaluation indicators was established by parametric modeling of the C-type tank and combining the characteristics of LNG ships. On this basis, the weight index was determined by using the hierarchical analysis method and fuzzy theory, and a function for optimizing the size and shape of the C-type tank was constructed, and then the optimal solution of the C-type tank was solved. The case confirms the effectiveness of the method of applying the evaluation system to the optimization design. This method can quickly obtain the size and shape of the C-type tank in the early stage of design, reduce design costs, and improve design efficiency.

[0004] The existing LNG filling device generally adopts a shore-based LNG tank filling device or a skid-mounted LNG tank filling device. However, the above technology has the following technical problems, such as the shore-based LNG tank filling device: In the drying and inerting stage, the air in the tank is replaced with normal temperature nitrogen; in the precooling stage, the normal temperature nitrogen is replaced with low temperature nitrogen; in the replacement stage, the nitrogen in the tank is replaced with natural gas (gaseous LNG); in the filling stage, the natural gas is replaced with liquefied natural gas. In these processes, the replaced gas is directly discharged into the atmosphere after being burned in the flare tower. These energies are not recycled, which will cause a lot of losses from the economic point of view. Since the greenhouse effect of natural gas is much stronger than that of carbon dioxide, natural gas needs to be discharged during the filling process, and it may also need to be discharged when the fuel tank pressure is too high, which will seriously aggravate the greenhouse effect.

[0005] For example, the skid-mounted LNG tank filling device: if the cooling and recovery device of BOG gas is not installed, there will be serious waste in long-term use, which is obviously inconsistent with the purpose of devoting to efficient utilization and development of resources and strengthening energy recovery and reuse; in terms of gas emissions, it directly discharges the gas to the outside through the vent pipe, which will cause serious pollution to the environment and aggravate the greenhouse effect. Summary of the invention

[0006] The purpose of the present invention is to provide an energy-saving, environmentally friendly, safe and effective LNG tank filling device for LNG transport ships.

[0007] To achieve the above object, the present invention provides the following technical solutions: An LNG tank filling device for an LNG transport ship comprises a filling tank truck, a nitrogen storage tank, a liquid tank, and a flare tower. The filling tank truck is connected to the LNG storage tank, and the LNG storage tank is respectively connected to a drying inerting system and a replacement system at the end away from the filling tank truck. The drying inerting system is connected between the LNG storage tank and the liquid tank, and the end of the liquid tank away from the drying inerting system is connected to the flare tower. One end of the nitrogen storage tank is connected to the drying inerting system, and the other end is connected to the replacement system. A precooling system is also connected between the liquid tank and the replacement system.

[0008] As a preferred solution of the present invention, a filling hose is connected between the filling tank truck and the LNG storage tank, a stop valve is connected to the filling hose near the filling tank truck end, a cryogenic submersible pump is connected to the outside of the filling hose, a coupling is connected to one end of the cryogenic submersible pump, and a motor is connected through the coupling.

[0009] As a preferred solution of the present invention, the LNG storage tank is connected to a pressure gauge and a liquid level gauge.

[0010] As a preferred embodiment of the present invention, the dry inerting system includes a filling skid, a vaporizer is arranged inside the filling skid, the vaporizer is communicated with seawater, the vaporizer is connected to the LNG storage tank through a pipeline, a safety valve is connected to the pipeline between the vaporizer and the LNG storage tank, a low-temperature submersible pump connected to the pipeline is arranged near the LNG storage tank end of the safety valve, the vaporizer is far away from the LNG storage tank end and is respectively connected to seawater and a nitrogen storage tank, and a low-temperature submersible pump is also arranged between the vaporizer and the nitrogen storage tank.

[0011] As a preferred embodiment of the present invention, a gas phase pipeline and a liquid phase pipeline are connected between the liquid tank and the vaporizer, and a three-way valve is connected to the gas phase pipeline and the liquid phase pipeline near the liquid tank. The same three-way valve is connected between the liquid tank and the flare tower.

[0012] As a preferred embodiment of the present invention, the replacement system includes an LNG recovery tank and a nitrogen recovery tank, wherein one end of the LNG recovery tank is connected to the LNG storage tank, and a shut-off valve and a cryogenic submersible pump are provided between the LNG recovery tank and the LNG storage tank, wherein one end of the nitrogen recovery tank is connected to the nitrogen storage tank, and a shut-off valve and a cryogenic submersible pump are provided between the LNG recovery tank and the nitrogen storage tank.

[0013] As a preferred embodiment of the present invention, the precooling system includes a pressurizer, one end of the pressurizer is connected to a condenser, the condenser is connected to a three-way valve between the flare tower and the liquid tank at an end away from the pressurizer, the condenser is interconnected with fresh water, the pressurizer is connected to a three-way valve at an end away from the condenser, the three-way valve is respectively connected to a natural gas return pipe and a nitrogen return pipe at an end away from the pressurizer, the other end of the natural gas return pipe is connected to an LNG recovery tank, and the other end of the nitrogen return pipe is connected to a nitrogen recovery tank.

[0014] In summary, the beneficial technical effects of the present invention are as follows: the present invention incorporates the concept of energy recycling, and achieves the purpose of energy conservation and environmental protection by recycling and reusing the natural gas and nitrogen that are to be discharged into the atmosphere after combustion. In addition, in terms of safety, an overpressure protection system is added, and a pressure gauge and a liquid level gauge are set to monitor the pressure and filling level changes in real time. This will help to timely discover potential risks and take necessary measures to prevent them before they occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification, but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a structural schematic diagram of an LNG tank filling device of an LNG transport ship according to this embodiment.

[0016] In the figure, 1. filling tank truck; 2. stop valve; 3. motor; 4. coupling; 5. cryogenic submersible pump; 6. filling hose; 7. liquid level gauge; 8. pressure gauge; 9. LNG storage tank; 10. safety valve; 11. vaporizer; 12. nitrogen storage tank; 13. gas phase pipeline; 14. liquid phase pipeline; 15. three-way valve; 16. liquid tank; 17. flare tower; 18. condenser; 19. pressurizer; 20. natural gas return pipe; 21. nitrogen return pipe; 22. LNG recovery tank; 23. nitrogen recovery tank; 24. filling skid. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] See also Figure 1 The present invention provides a technical solution: an LNG tank filling device for an LNG transport ship, the device comprising a filling tank truck 1, a nitrogen storage tank 12, a liquid tank 16, and a flare tower 17, the filling tank truck 1 is connected to an LNG storage tank 9, and the ends of the LNG storage tank 9 away from the filling tank truck 1 are respectively connected to a drying and inerting system and a replacement system, the drying and inerting system is connected between the LNG storage tank 9 and the liquid tank 16, and the end of the liquid tank 16 away from the drying and inerting system is connected to the flare tower 17, one end of the nitrogen storage tank 12 is connected to the drying and inerting system, and the other end is connected to the replacement system, and a precooling system is also connected between the liquid tank 16 and the replacement system.

[0020] A filling hose 6 is connected between the filling tank truck 1 and the LNG storage tank 9. A stop valve 2 is connected to the filling hose 6 near the end of the filling tank truck 1. A cryogenic submersible pump 5 is connected to the outside of the filling hose 6. A coupling 4 is connected to one end of the cryogenic submersible pump 5, and a motor 3 is connected through the coupling 4.

[0021] The LNG storage tank 9 is connected to a pressure gauge 8 and a liquid level gauge 7 .

[0022] The dry inerting system includes a filling skid 24, in which a vaporizer 11 is provided. The vaporizer 11 is in communication with seawater. The vaporizer 11 is connected to the LNG storage tank 9 through a pipeline. A safety valve 10 is connected to the pipeline between the vaporizer 11 and the LNG storage tank 9. The safety valve 10 is provided with a cryogenic submersible pump 5 connected to the pipeline at the end close to the LNG storage tank 9. The vaporizer 11 is connected to the seawater and the nitrogen storage tank 12 at the end far from the LNG storage tank 9, and a cryogenic submersible pump 5 is also provided between the vaporizer 11 and the nitrogen storage tank 12.

[0023] A gas phase pipeline 13 and a liquid phase pipeline 14 are connected between the liquid tank 16 and the vaporizer 11 . A three-way valve 15 is connected to the gas phase pipeline 13 and the liquid phase pipeline 14 near the liquid tank 16 . A similar three-way valve 15 is connected between the liquid tank 16 and the flare tower 17 .

[0024] Specifically, liquid nitrogen flows out from the nitrogen storage tank 12, is heated to -30°C by the vaporizer 11 in the filling skid 24, is diverted from the gas phase pipeline 13 through the three-way valve 15, and is injected into the liquid tank 16. The gas in the liquid tank 16 is diverted from the lower pipeline through the three-way valve 15 and is burned and discharged into the atmosphere through the flare tower 17.

[0025] The replacement system includes an LNG recovery tank 22 and a nitrogen recovery tank 23, wherein one end of the LNG recovery tank 22 is connected to the LNG storage tank 9, and a stop valve 2 and a cryogenic submersible pump 5 are provided between the LNG recovery tank 22 and the LNG storage tank 9, wherein one end of the nitrogen recovery tank 23 is connected to the nitrogen storage tank 12, and a stop valve 2 and a cryogenic submersible pump 5 are provided between the LNG recovery tank 22 and the nitrogen storage tank 12.

[0026] The precooling system includes a pressurizer 19, one end of the pressurizer 19 is connected to a condenser 18, the end of the condenser 18 away from the pressurizer 19 is connected to a three-way valve 15 between the flare tower 17 and the liquid tank 16, the condenser 18 is interconnected with fresh water, the end of the pressurizer 19 away from the condenser 18 is connected to the three-way valve 15, the end of the three-way valve 15 away from the pressurizer 19 is respectively connected to a natural gas return pipe 20 and a nitrogen return pipe 21, the other end of the natural gas return pipe 20 is connected to an LNG recovery tank 22, and the other end of the nitrogen return pipe 21 is connected to a nitrogen recovery tank 23.

[0027] Specifically, in the pre-cooling stage, liquid nitrogen is output from the nitrogen storage tank 12, and converted into low-temperature nitrogen at -160°C through the vaporizer 11 in the filling skid 24. The low-temperature nitrogen enters the liquid tank 16 through the liquid phase pipeline 14, and the room-temperature nitrogen in the tank is discharged from the gas phase pipeline 13, diverted through the three-way valve 15, condensed by the condenser 18 and pressurized by the pressurizer 19, and then recovered from the nitrogen recovery pipe to the nitrogen recovery tank 23 through the three-way valve 15. When the internal temperature of the liquid tank 16 drops to -110°C to -120°C, the pre-cooling process ends, and then enters the replacement stage.

[0028] In the replacement phase, LNG is output from the LNG storage tank 9, converted into natural gas at -130°C via the vaporizer 11 in the filling skid 24, and enters the liquid tank 16 via the gas phase pipeline 13. The low-temperature nitrogen in the liquid tank 16 is then discharged through the liquid phase pipeline 14, diverted by the three-way valve 15, condensed by the condenser 18 and pressurized by the pressurizer 19, and then recovered from the nitrogen recovery pipe to the nitrogen recovery tank 23 via the three-way valve 15. After the replacement process is completed, the LNG filling phase begins.

[0029] During the LNG filling stage, LNG is output from the LNG storage tank 9 and injected into the liquid tank 16 through the liquid phase pipeline 14. Natural gas is discharged from the gas phase pipeline 13, diverted by the three-way valve 15, condensed by the condenser 18 and pressurized by the pressurizer 19, and then recovered from the LNG recovery pipe to the LNG recovery tank 22 through the three-way valve 15. The filling stage ends when the filling amount reaches the predetermined target value.

[0030] When the ship is filled, the staff determines that the liquid level in the recovery tank reaches 60%-80%, meeting the return requirement, and the other valves of the LNG filling device are closed, and the valve between the recovery tank and the storage tank is opened. The LNG is transported to the respective storage tanks through their respective pipelines.

[0031] The working principle of the present invention is as follows: the LNG storage tank 9 is replenished with LNG through a tank truck, the LNG storage tank 9 and the nitrogen storage tank 12 are connected to the vaporizer 11, and the form of the filling gas for the liquid tank 16 is selected through the vaporizer 11. The liquid tank 16 selects through a four-way valve whether the internal gas is discharged to the atmosphere through the flare tower 17, or condensed through the condenser 18 and then pressurized through the pressurizer 19 and transported to the nitrogen recovery tank 23 through the nitrogen return pipe 21 or transported to the LNG recovery tank 22 through the natural gas return pipe 20, and finally the liquid in each recovery tank is transported to each recovery tank through their own pipelines.

Claims

1. An LNG tank filling device for an LNG carrier, characterized in that: The device comprises a filling tank truck (1), a nitrogen storage tank (12), a liquid tank (16), and a flare tower (17). The filling tank truck (1) is connected to an LNG storage tank (9), and the end of the LNG storage tank (9) away from the filling tank truck (1) is respectively connected to a drying inerting system and a replacement system. The drying inerting system is connected between the LNG storage tank (9) and the liquid tank (16), and the end of the liquid tank (16) away from the drying inerting system is connected to the flare tower (17). One end of the nitrogen storage tank (12) is connected to the drying inerting system, and the other end is connected to the replacement system. A precooling system is also connected between the liquid tank (16) and the replacement system.

2. The LNG tank (16) filling device of the LNG carrier according to claim 1, characterized in that: A filling hose (6) is connected between the filling tank truck (1) and the LNG storage tank (9); the filling hose (6) is connected to a stop valve (2) at the end close to the filling tank truck (1); the outside of the filling hose (6) is connected to a cryogenic submersible pump (5); one end of the cryogenic submersible pump (5) is connected to a coupling (4), and a motor (3) is connected via the coupling (4).

3. The LNG tank (16) filling device of the LNG carrier according to claim 2, characterized in that: The LNG storage tank (9) is connected to a pressure gauge (8) and a liquid level meter (7).

4. The LNG tank (16) filling device of the LNG carrier according to claim 2, characterized in that: The dry inerting system comprises a filling skid (24), a vaporizer (11) is arranged inside the filling skid (24), the vaporizer (11) is in communication with seawater, the vaporizer (11) is connected to the LNG storage tank (9) through a pipeline, a safety valve (10) is connected to the pipeline between the vaporizer (11) and the LNG storage tank (9), a low-temperature submersible pump (5) connected to the pipeline is arranged at the end of the safety valve (10) close to the LNG storage tank (9), and the end of the vaporizer (11) far from the LNG storage tank (9) is connected to the seawater and the nitrogen storage tank (12), and a low-temperature submersible pump (5) is also arranged between the vaporizer (11) and the nitrogen storage tank (12).

5. The LNG tank (16) filling device of the LNG carrier according to claim 3, characterized in that: A gas phase pipeline (13) and a liquid phase pipeline (14) are connected between the liquid tank (16) and the vaporizer (11); the gas phase pipeline (13) and the liquid phase pipeline (14) are both connected to a three-way valve (15) near the liquid tank (16); and a similar three-way valve (15) is connected between the liquid tank (16) and the flare tower (17).

6. The LNG tank (16) filling device of the LNG carrier according to claim 5, characterized in that: The replacement system comprises an LNG recovery tank (22) and a nitrogen recovery tank (23), wherein one end of the LNG recovery tank (22) is connected to an LNG storage tank (9), and a stop valve (2) and a cryogenic submersible pump (5) are provided between the LNG recovery tank (22) and the LNG storage tank (9), wherein one end of the nitrogen recovery tank (23) is connected to a nitrogen storage tank (12), and a stop valve (2) and a cryogenic submersible pump (5) are provided between the LNG recovery tank (22) and the nitrogen storage tank (12).

7. The LNG tank (16) filling device of the LNG carrier according to claim 6, characterized in that: The precooling system comprises a pressurizer (19), one end of the pressurizer (19) is connected to a condenser (18), the end of the condenser (18) away from the pressurizer (19) is connected to a three-way valve (15) between a flare tower (17) and a liquid tank (16), the condenser (18) is interconnected with fresh water, the end of the pressurizer (19) away from the condenser (18) is connected to the three-way valve (15), the end of the three-way valve (15) away from the pressurizer (19) is respectively connected to a natural gas return pipe (20) and a nitrogen return pipe (21), the other end of the natural gas return pipe (20) is connected to an LNG recovery tank (22), and the other end of the nitrogen return pipe (21) is connected to a nitrogen recovery tank (23).

Images