An ammonia-powered supertanker cargo hold unloading and alternative inert gas supply system

Abstract

The present invention proposes an ammonia-powered supertanker cargo hold unloading and inert gas replacement supply system, which includes three subsystems: an ammonia fuel supply system, an ammonia combustion system, and an unloading and gas supply system. When the supertanker transports crude oil from the cargo hold to a shore-based oil depot through an unloading pump at an unloading port, the present invention adopts an unloading and gas supply system, which can replace the inert gas with ammonia gas vaporized from the ammonia fuel on the ship and pass it into the cargo hold. At the same time, the method of using an electric motor as a prime mover and connecting to shore power is adopted, which improves the energy utilization efficiency of the prime mover, thereby improving the efficiency of the entire unloading device and solving the problem of low thermal efficiency of the prime mover using a steam turbine. In addition, the system does not generate exhaust gas during the crude oil transportation process at the unloading port, thereby not polluting the port environment, and is in line with the development concept of green ports and green ships. Therefore, the system has excellent practical application value and economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of ships, and in particular to an ammonia-powered supertanker cargo hold unloading and alternative inert gas supply system. Background Art

[0002] Supertankers, or VLCCs, are ships specially used to transport crude oil. Due to the huge volume of crude oil, the deadweight of oil tankers can reach about 300,000 tons, so supertankers have become the main ships for transporting crude oil. Supertankers are equipped with multiple longitudinal bulkheads to increase the stability of the ship; in addition, multiple transverse bulkheads are also installed to increase the anti-sinking ability. Therefore, supertankers have a large number of cargo holds, up to more than 20.

[0003] When a supertanker carrying crude oil arrives at the unloading port, it is necessary to unload the liquid cargo stored in the cargo hold. The existing unloading process is to transport the liquid cargo in the cargo hold to the oil depot at the dock through an unloading pump. The flow rate of the unloading pump is very large, and more than 10,000 tons can be unloaded within 1 hour. Therefore, the power of the unloading pump is relatively large, and it is usually driven by a steam turbine to operate it. The steam required by the steam turbine comes from the steam generated by the ship's auxiliary fuel boiler. At the same time, the exhaust gas generated by the ship's auxiliary boiler burning fuel is washed with seawater and turned into inert gas and passed into each cargo hold to avoid a certain vacuum in the cargo hold, which makes it difficult for the unloading pump to inhale; if the outside air is directly introduced above the cargo hold during the unloading process, it will mix with the liquid cargo oil and gas in the cargo hold, causing an explosion. Therefore, this is why tankers need to introduce inert gas during the unloading process.

[0004] At present, the above unloading process has the following problems: First, as we all know, the thermal engine efficiency of the steam turbine in the above unloading process is low, about 29%, so the auxiliary boiler consumes more fuel oil during the unloading process; second, the ship's fuel oil auxiliary boiler burns fuel oil to produce more exhaust gas, and the capacity of the supertanker cargo hold is limited, so only part of the exhaust gas is filled into the cargo hold, and the remaining large amount of exhaust gas is discharged into the atmosphere, which causes certain pollution to the port environment with high emission requirements; third, the exhaust gas generated by the auxiliary boiler burning fuel oil is washed by seawater and passed into the cargo hold. In this process, since the exhaust gas from seawater washing is washed by seawater near the port, it will inevitably cause certain pollution to the port environment, which is contrary to the current concept of green ports and green ships. It can be seen that the operation mode of burning fuel oil in the ship's auxiliary boiler to provide power for the unloading pump and provide inert gas for the cargo hold has obvious shortcomings and deficiencies.

[0005] In view of the above problems, the present invention proposes an ammonia-powered supertanker cargo hold unloading and inert gas replacement supply system, which can replace the inert gas with ammonia gas obtained by vaporizing its own ammonia fuel, and adopts the prime mover as an electric motor and connects to shore power. Compared with the traditional prime mover using a steam turbine, the system improves the energy utilization rate of the prime mover, and at the same time does not generate exhaust gas, thereby not polluting the port environment, and is in line with the development concept of green ports and green ships. Summary of the invention

[0006] The purpose of the present invention is to solve the above technical problems and propose an ammonia-powered supertanker cargo hold unloading and alternative inert gas supply system. When the supertanker transports crude oil from the cargo hold to the shore-based oil depot through the unloading pump at the unloading port, the system can pass the ammonia gas vaporized from the ammonia fuel on the ship into the cargo hold. At the same time, the prime mover is an electric motor, and the electric motor is connected to the shore power to drive the unloading pump. Compared with the traditional prime mover using a steam turbine to drive the circulating pump, the system improves the energy utilization of the prime mover, thereby improving the unloading efficiency of the entire unloading device; in addition, the system can also supply the ammonia gas stored in the cargo hold to the main diesel engine of the ship for fuel during the voyage after the supertanker unloads. The system does not generate exhaust gas during the crude oil transportation process at the unloading port, and thus does not pollute the port environment, which is in line with the development concept of green ports and green ships. Therefore, the system has excellent practical application value and economic benefits.

[0007] This system consists of three subsystems: an ammonia fuel supply system, an ammonia combustion system, and an unloading and gas supply system. The ammonia fuel supply system includes: an ammonia fuel tank, a transfer pump, a primary booster pump, a secondary booster pump, a liner water heater, and a ship's main diesel engine. The ammonia combustion system includes: a cargo hold, an ammonia outlet valve, an air extraction pump, a compressor, a secondary booster pump, a liner water heater, a ship's main diesel engine, a fan, an exhaust gas scrubbing unit, and an inert gas supply valve. The unloading and gas supply system includes: an ammonia fuel tank, a transfer pump, a vaporizing heat exchanger, an ammonia inlet valve, a cargo hold, a liquid cargo outlet valve, an unloading pump, a shore-based oil depot, an electric motor, and a shore-based power supply station.

[0008] In the ammonia fuel supply system, the transfer pump is installed at the bottom of the ammonia fuel tank, and the transfer pump is connected to the first-level booster pump through a pipeline; the first-level booster pump is connected to the second-level booster pump through a pipeline; the second-level booster pump is connected to the cylinder jacket water heater through a pipeline; the cylinder jacket water heater is connected to the main diesel engine of the ship through a pipeline.

[0009] In the ammonia combustion system, the cargo hold is connected to the ammonia outlet valve through a pipeline at the top; the ammonia outlet valve is connected to the suction pump through a pipeline; the suction pump is connected to the compressor through a pipeline; the compressor is connected to the secondary boost pump through a pipeline; the secondary boost pump is connected to the cylinder jacket water heater through a pipeline; the cylinder jacket water heater is connected to the ship's main diesel engine through a pipeline; the exhaust gas outlet of the ship's main diesel engine is connected to the exhaust gas collection unit through a pipeline, and then the exhaust gas collection unit is connected to the fan through a pipeline; the fan is connected to the exhaust gas washing unit through a pipeline; the exhaust gas washing unit is connected to the inert gas supply valve through a pipeline; the inert gas supply valve is connected to the top of the cargo hold through a pipeline.

[0010] In the unloading and gas supply system, the transfer pump is installed at the bottom of the ammonia fuel tank, and the transfer pump is connected to the vaporizing heat exchanger through a pipeline; the vaporizing heat exchanger is connected to the ammonia inlet valve through a pipeline; the ammonia inlet valve is connected to the top of the cargo hold through a pipeline; the cargo hold is connected to the liquid cargo outlet valve through a pipeline at the bottom; the liquid cargo outlet valve is connected to the unloading pump through a pipeline, wherein the unloading pump is driven by an electric motor, the power source of the electric motor is provided by the shore-based power supply station, and the unloading pump is connected to the shore-based oil depot through a pipeline.

[0011] Furthermore, this system defines that there are n cargo holds on the supertanker, namely C1, C2, ..., Cn cargo holds. The above connection is based on the connection process of one cargo hold. In fact, the connection process of C1, C2, ..., Cn cargo holds is the same.

[0012] When a supertanker is sailing from the loading port to the unloading port after loading crude oil, the ship adopts an ammonia fuel supply system, and the transfer pump transfers the liquid ammonia fuel from the ammonia fuel tank, flows through the pipeline to the first-stage booster pump, is pressurized by the first-stage booster pump, and then flows through the second-stage booster pump for re-pressurization, and then flows through the cylinder jacket water heater through the pipeline for final heating using the cylinder jacket water to meet the supply temperature of the ship's main diesel engine for fueling the ship's main diesel engine.

[0013] When the supertanker arrives at the unloading port: the ship adopts an unloading and gas supply system. When the ship docks at the unloading port and is about to unload, the ammonia inlet valve and liquid cargo outlet valve corresponding to the C1 cargo hold are opened first. At this time, the unloading pump starts to transport the crude oil in the C1 cargo hold to the shore-based oil depot under the drive of the electric motor, and the power of the electric motor comes from the shore-based power supply station; while the unloading pump is transporting the crude oil, in order to avoid inconsistent pressure inside and outside the C1 cargo hold, the liquid ammonia fuel in the ammonia fuel tank is transported out by the transfer pump, flows through the pipeline to the vaporizing heat exchanger, and is heated by the vaporizing heat exchanger to turn the liquid ammonia into ammonia gas, and the ammonia gas is then filled into the C1 cargo hold through the pipeline to balance the pressure.

[0014] When the C1 cargo hold is unloaded, its corresponding ammonia inlet valve and liquid cargo outlet valve are closed, and then the corresponding ammonia inlet valve and liquid cargo outlet valve of the C2 cargo hold are opened. At this time, the unloading pump starts to transport the crude oil in the C2 cargo hold to the shore-based oil depot under the drive of the motor. In order to avoid inconsistent pressure inside and outside the C2 cargo hold, the liquid ammonia fuel in the ammonia fuel tank is transferred out by the transfer pump, and flows through the pipeline to the vaporizing heat exchanger. After the vaporizing heat exchanger is heated, the liquid ammonia is converted into ammonia gas, and the ammonia gas is then filled into the C2 cargo hold through the pipeline to balance the pressure. By analogy, the unloading and gas supply process of the C3, C4, ..., Cn cargo holds are the same as those of the C1 and C2 cargo holds. Among them, during the unloading and gas supply process, the ammonia outlet valve and inert gas supply valve corresponding to the C1, C2, ..., Cn cargo holds are all in a closed state.

[0015] When a supertanker with cargo holds filled with ammonia is sailing from the unloading port to the loading port: Since a large amount of ammonia is filled into cargo holds C1, C2, ..., Cn at the unloading port, the ship uses an ammonia combustion system and an ammonia fuel supply system to deliver a mixed fuel of ammonia and liquid ammonia to the ship's main diesel engine for fuel. In this process, the ammonia outlet valve corresponding to the C1 cargo hold is first opened, and the ammonia in the C1 cargo hold is transported from the pipeline to the compressor under the action of the vacuum pump for preliminary pressurization. While the ammonia in the above-mentioned C1 cargo hold is being transported to the ship's main diesel engine for fuel, the ship also uses the ammonia fuel supply system to deliver liquid ammonia fuel to the ship's main diesel engine for fuel. At this time, the liquid ammonia in the ammonia fuel tank is transferred by a transfer pump, and then mixed with the ammonia gas compressed by the compressor after being pressurized by the first-stage booster pump. The compressed ammonia gas is liquefied with the help of the cold energy of the liquid ammonia fuel transferred from the ammonia fuel tank. The two enter the second-stage booster pump together for pressurization, and then are heated by the cylinder jacket water heater to meet the supply temperature of the ship's main diesel engine for fuel for the ship's main diesel engine.

[0016] In the process of pumping ammonia gas from the C1 cargo hold through the vacuum pump, when the vacuum degree of ammonia gas in the C1 cargo hold is 95%, the ammonia gas outlet valve corresponding to the C1 cargo hold is closed, and the inert gas supply valve corresponding to C1 is opened. At the same time, the ammonia gas outlet valve corresponding to the C2 cargo hold is opened, and part of the exhaust gas discharged by the ship's main diesel engine is blown into the exhaust gas washing unit through the fan. After the exhaust gas washing unit removes dust and water vapor, the exhaust gas is converted into inert gas and passed into the C1 cargo hold, so that the pressure in the cargo hold is normal pressure, and the pressure inside and outside the cargo hold is consistent, so as to avoid explosion after the outside air enters the cargo hold. When the C1 cargo hold is filled with the required inert gas, the inert gas supply valve corresponding to the C1 cargo hold is closed. The above is the ammonia gas delivery process of the C1 cargo hold, and the process of the inert gas generated by the ship's main diesel engine passing into the C1 cargo hold.

[0017] Similarly, the ammonia transportation process of C2, C3, C4, ..., Cn cargo holds and the process of the ship's main diesel engine generating inert gas and passing it into C2, C3, C4, ..., Cn cargo holds are the same as those of C1 cargo hold.

[0018] Beneficial effects of the present invention:

[0019] 1. The present invention provides an unloading system and an alternative inert gas supply system during the unloading process of a supertanker. During the unloading process, the system neither discharges exhaust gas into the atmosphere at the port nor requires the use of seawater to wash the exhaust gas. Therefore, the system will not pollute the port environment and is in line with the development concept of green ports and green ships.

[0020] 2. This system adopts the method of using an electric motor as the prime mover and connecting it to shore power, which improves the energy utilization efficiency of the prime mover, thereby improving the efficiency of the entire unloading device and solving the problem of low thermal efficiency of the prime mover using a steam turbine. Therefore, this system has excellent practical application value and economic benefits.

[0021] 3. This system cleverly replaces inert gas with ammonia and introduces it into the cargo hold at the unloading port, and can supply this part of ammonia to the ship's main diesel engine for fuel during the ship's voyage. This system has a simple structure and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the system used in the process of unloading cargo from a ship according to the present invention;

[0023] Figure 2 A schematic diagram of the system used in the process of a ship sailing from a discharge port to a loading port in the present invention;

[0024] Figure 3 Schematic diagram of the system used by the ship when arriving at the discharge port and sailing on various routes;

[0025] In the attached figure: 1. Ammonia fuel tank; 2. Transfer pump; 3. Vaporizing heat exchanger; 4. Ammonia inlet valve; 5. Cargo hold; 6. Liquid cargo outlet valve; 7. Unloading pump; 8. Shore-based oil depot; 9. Electric motor; 10. Shore-based power supply station; 11. Ammonia outlet valve; 12. Suction pump; 13. Compressor; 14. Secondary booster pump; 15. Cylinder jacket water heater; 16. Ship's main diesel engine; 17. Inert gas supply valve; 18. Fan; 19. Exhaust gas scrubbing unit; 20. Primary booster pump. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0027] An ammonia powered supertanker cargo hold unloading and alternative inert gas supply system, such as Figure 1 and Figure 2 As shown, the system consists of three subsystems: an ammonia fuel supply system, an ammonia combustion system, and an unloading and gas supply system. The unloading and gas supply system includes: an ammonia fuel tank 1, a transfer pump 2, a vaporizing heat exchanger 3, an ammonia inlet valve 4, a cargo tank 5, a liquid cargo outlet valve 6, an unloading pump 7, a shore-based oil depot 8, a motor 9, and a shore-based power supply station 10. The ammonia combustion system includes: a cargo tank 5, an ammonia outlet valve 11, an air extraction pump 12, a compressor 13, a secondary booster pump 14, a cylinder jacket water heater 15, a ship's main diesel engine 16, a fan 18, an exhaust gas scrubbing unit 19, and an inert gas supply valve 17. The ammonia fuel supply system includes: an ammonia fuel tank 1, a transfer pump 2, a primary booster pump 20, a secondary booster pump 14, a cylinder jacket water heater 15, and a ship's main diesel engine 16.

[0028] like Figure 3 As shown, in this system: when the supertanker is unloading at the unloading port, the unloading and gas supply system is used; when the supertanker is sailing from the loading port to the unloading port after loading crude oil, the ammonia fuel supply system is used; when the supertanker is sailing from the unloading port to the loading port, the ammonia gas combustion system and the ammonia fuel supply system are used at the same time. Assume that the supertanker has a total of n cargo holds, namely C1, C2, ..., Cn cargo holds.

[0029] In the unloading and gas supply system, the ammonia fuel tank 1 is used to store liquid ammonia fuel, and the transfer pump 2 is installed at the bottom of the ammonia fuel tank 1, and the transfer pump 2 is connected to the vaporizing heat exchanger 3 through a pipeline; the vaporizing heat exchanger 3 is connected to the ammonia inlet valve 4 through a pipeline; the ammonia inlet valve 4 is connected to the top of the cargo hold 5 through a pipeline; the cargo hold 5 is connected to the liquid cargo outlet valve 6 at the bottom through a pipeline; the liquid cargo outlet valve 6 is connected to the unloading pump 7 through a pipeline, wherein the unloading pump 7 is driven by an electric motor 9, and the power source of the electric motor 9 is provided by a shore-based power supply station 10, and the unloading pump 7 is connected to the shore-based oil depot 8 through a pipeline.

[0030] In the ammonia fuel supply system, the barge pump 2 is installed at the bottom of the ammonia fuel tank 1, and the barge pump 2 is connected to the primary boost pump 20 through a pipeline; the primary boost pump 20 is connected to the secondary boost pump 14 through a pipeline; the secondary boost pump 14 is connected to the cylinder jacket water heater 15 through a pipeline; the cylinder jacket water heater 15 is connected to the ship's main diesel engine 16 through a pipeline.

[0031] In the ammonia combustion system, the cargo hold 5 is connected to the ammonia outlet valve 11 at the top through a pipeline; the ammonia outlet valve 11 is connected to the suction pump 12 through a pipeline; the suction pump 12 is connected to the compressor 13 through a pipeline; the compressor 13 is connected to the secondary boost pump 14 through a pipeline; the secondary boost pump 14 is connected to the cylinder jacket water heater 15 through a pipeline; the cylinder jacket water heater 15 is connected to the ship's main diesel engine 16 through a pipeline; the exhaust gas outlet of the ship's main diesel engine 16 is connected to the exhaust gas collection unit through a pipeline, and then the exhaust gas collection unit is connected to the fan 18 through a pipeline; the fan 18 is connected to the exhaust gas washing unit 19 through a pipeline; the exhaust gas washing unit 19 is connected to the inert gas supply valve 17 through a pipeline; the inert gas supply valve 17 is connected to the top of the cargo hold 5 through a pipeline.

[0032] When a supertanker is sailing from a loading port to a unloading port after loading crude oil, the ship adopts an ammonia fuel supply system, and the transfer pump 2 transfers the liquid ammonia fuel in the ammonia fuel tank 1, flows through a pipeline to the first-stage booster pump 20, is pressurized by the first-stage booster pump 20, and then flows through the second-stage booster pump 14 for re-pressurization, and then flows through the cylinder jacket water heater 15 through a pipeline for final heating using the cylinder jacket water to meet the supply temperature of the ship's main diesel engine 16 for fueling the ship's main diesel engine 16.

[0033] When the supertanker arrives at the unloading port: the ship adopts an unloading and gas supply system. When the ship docks at the unloading port and is about to unload, the ammonia inlet valve 4 and the liquid cargo outlet valve 6 corresponding to the C1 cargo hold are opened first. At this time, the unloading pump 7 starts to transport the crude oil in the C1 cargo hold to the shore-based oil depot 8 under the drive of the motor 9, wherein the power of the motor 9 comes from the shore-based power supply station 10; while the unloading pump 7 transports the crude oil, in order to avoid inconsistent pressure inside and outside the C1 cargo hold, the liquid ammonia fuel in the ammonia fuel tank 1 is transported out by the transfer pump 2, flows through the pipeline to the vaporizing heat exchanger 3, and is heated by the vaporizing heat exchanger 3 to convert the liquid ammonia into ammonia gas, and the ammonia gas is then filled into the C1 cargo hold through the pipeline to balance the pressure.

[0034] When the C1 cargo hold is unloaded, the corresponding ammonia inlet valve 4 and liquid cargo outlet valve 6 are closed, and the corresponding ammonia inlet valve 4 and liquid cargo outlet valve 6 of the C2 cargo hold are opened. At this time, the unloading pump 7 starts to transport the crude oil in the C2 cargo hold to the shore-based oil depot 8 under the drive of the motor 9. In order to avoid inconsistent pressure inside and outside the C2 cargo hold, the liquid ammonia fuel in the ammonia fuel tank 1 is transferred out by the transfer pump 2, flows through the pipeline to the vaporizing heat exchanger 3, and is heated by the vaporizing heat exchanger 3 to convert the liquid ammonia into ammonia gas. The ammonia gas is then filled into the C2 cargo hold through the pipeline to balance the pressure. By analogy, the unloading and gas supply processes of the C3, C4, ..., Cn cargo holds are the same as those of the C1 and C2 cargo holds. In the unloading and gas supply processes, the ammonia outlet valves 11 and the inert gas supply valves 17 corresponding to the C1, C2, ..., Cn cargo holds are all in a closed state.

[0035] When the supertanker with each cargo hold filled with ammonia is sailing from the unloading port to the loading port: Since a large amount of ammonia is filled into each cargo hold C1, C2, ..., Cn at the unloading port, the ship uses the ammonia combustion system and the ammonia fuel supply system to respectively deliver a mixed fuel of ammonia and liquid ammonia (-33°C) to the ship's main diesel engine 16 for fuel. In this process, the ammonia outlet valve 11 corresponding to the C1 cargo hold is first opened, and the ammonia in the C1 cargo hold is transported from the pipeline to the compressor 13 under the action of the vacuum pump 12 for preliminary pressurization. While the ammonia in the above-mentioned C1 cargo hold is delivered to the ship's main diesel engine 16 for fuel, the ship also uses the ammonia fuel supply system to deliver liquid ammonia fuel to the ship's main diesel engine 16 for fuel. At this time, the liquid ammonia in the ammonia fuel tank 1 is transferred by the transfer pump 2, and then mixed with the ammonia gas compressed by the compressor 13 after being pressurized by the first-level booster pump 20. The compressed ammonia gas is liquefied with the help of the cold energy of the liquid ammonia fuel in the ammonia fuel tank 1. The two enter the second-level booster pump 14 for pressurization, and then are heated by the cylinder jacket water heater 15 to meet the supply temperature of the ship's main diesel engine 16 for fuel for the ship's main diesel engine 16.

[0036] In the process of extracting ammonia from the C1 cargo hold through the vacuum pump 12, when the ammonia vacuum in the C1 cargo hold is 95%, the ammonia outlet valve 11 corresponding to the C1 cargo hold is closed, and the inert gas supply valve 17 corresponding to C1 is opened, and the ammonia outlet valve 11 corresponding to the C2 cargo hold is opened at the same time, and the ship's main diesel engine 16 passes part of the exhaust gas discharged into the exhaust gas collection unit, and then blows the exhaust gas in the exhaust gas collection unit into the exhaust gas washing unit 19 through the fan 18. After the exhaust gas is processed by the exhaust gas washing unit 19 to remove dust and water vapor, it becomes inert gas and passes into the C1 cargo hold, so that the pressure in the C1 cargo hold is normal pressure, and the pressure inside and outside the C1 cargo hold is consistent, so as to avoid explosion after the outside air enters the C1 cargo hold. When the C1 cargo hold is filled with the required inert gas, the inert gas supply valve 17 corresponding to the C1 cargo hold is closed.

[0037] Similarly, the ammonia delivery process of the C2, C3, C4, ..., Cn cargo holds and the process of the ship's main diesel engine 16 generating inert gas and passing it into the C2, C3, C4, ..., Cn cargo holds are the same as those of the C1 cargo hold.

[0038] During the ammonia combustion process in the above cargo holds, only when the ammonia in the C1 cargo hold is used up (ammonia vacuum is 95%), the ammonia in the C2 cargo hold will be burned, and so on, until the C3, C4, ..., Cn cargo holds are used up in turn.

[0039] The ammonia gas pressurized by the compressor 13 is liquefied by utilizing the cold energy of the liquid ammonia in the ammonia fuel tank 1. Therefore, the compressor 13 does not need to pressurize the ammonia gas to a higher pressure to achieve liquefaction, thereby reducing the power consumption of the compressor 13.

[0040] During the voyage from the unloading port to the loading port, the power consumption required for liquefying the ammonia in the cargo hold 5 by the compressor 13 is very high. In order to optimize the solution, the present invention delivers a mixed fuel of the ammonia in each cargo hold and the liquid ammonia in the ammonia fuel tank 1 to the ship's main diesel engine 16 for combustion, wherein the mixing ratio of ammonia to liquid ammonia is 1:2, and the temperature of the liquid ammonia is -33°C. During the mixing process, the cold energy of the liquid ammonia in the ammonia fuel tank 1 is used to liquefy the ammonia in the cargo hold 5, which can greatly reduce the power consumption of the compressor 13. Since the calorific value of ammonia is relatively small, supertankers usually consume about 150 tons of ammonia fuel per day. In this system, the total volume of ammonia stored in the cargo hold 5 is 300,000m 3 , with a total mass of approximately 227 tons. If ammonia gas and liquid ammonia are mixed in a ratio of 1:2 for combustion, the ammonia gas in each cargo hold will be completely burned after about 108 hours of sailing (within 5 days). Since the time for a supertanker to sail empty-handed from the loading port to the unloading port is usually relatively long, most of which is more than half a month, the ammonia gas in each cargo hold will be completely burned during the empty-handed sailing. After the ammonia gas is completely burned, the ammonia fuel for the remaining section of the supertanker will be provided by the ammonia fuel tank 1.

[0041] The above is only a preferred embodiment of the present invention. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An ammonia powered supertanker cargo hold unloading and inert gas replacement supply system, characterized in that: This system includes three subsystems: ammonia fuel supply system, ammonia combustion system, and unloading and gas supply system. The unloading and gas supply system is used when the supertanker is unloading at the unloading port; the ammonia fuel supply system is used when the supertanker is sailing from the loading port to the unloading port after loading crude oil; When a supertanker sails from the unloading port to the loading port, it uses both the ammonia combustion system and the ammonia fuel supply system. The unloading and gas supply system comprises: an ammonia fuel tank (1), a transfer pump (2), a vaporizing heat exchanger (3), an ammonia inlet valve (4), a cargo tank (5), a liquid cargo outlet valve (6), an unloading pump (7), a shore-based oil depot (8), an electric motor (9), and a shore-based power supply station (10), wherein the cargo tanks (5) have a total of n, namely C1, C2, ..., Cn cargo tanks, In the unloading and gas supply system, the transfer pump (2) is installed at the bottom of the ammonia fuel tank (1), and the transfer pump (2) is connected to the vaporizing heat exchanger (3) through a pipeline; the vaporizing heat exchanger (3) is connected to the ammonia inlet valve (4) through a pipeline; the ammonia inlet valve (4) is connected to the top of the cargo hold (5) through a pipeline; the cargo hold (5) is connected to the liquid cargo outlet valve (6) at the bottom through a pipeline; the liquid cargo outlet valve (6) is connected to the unloading pump (7) through a pipeline, wherein the unloading pump (7) is driven by an electric motor (9), and the electric power source of the electric motor (9) is provided by a shore-based power supply station (10); the unloading pump (7) is connected to the shore-based oil depot (8) through a pipeline, The ammonia combustion system comprises a cargo hold (5), an ammonia outlet valve (11), an air extraction pump (12), a compressor (13), a secondary booster pump (14), a cylinder jacket water heater (15), a ship main diesel engine (16), a fan (18), an exhaust gas scrubbing unit (19) and an inert gas supply valve (17). In the ammonia combustion system, the cargo hold (5) is connected to an ammonia outlet valve (11) at the top through a pipeline; the ammonia outlet valve (11) is connected to an air extraction pump (12) through a pipeline; the air extraction pump (12) is connected to a compressor (13) through a pipeline; the compressor (13) is connected to a secondary booster pump (14) through a pipeline; the secondary booster pump (14) is connected to a jacket water heater (15) through a pipeline; the jacket water heater (15) is connected to a ship main diesel engine (16) through a pipeline; the exhaust gas discharge port of the ship main diesel engine (16) is connected to an exhaust gas collection unit through a pipeline, and then the exhaust gas collection unit is connected to a fan (18) through a pipeline; the fan (18) is connected to an exhaust gas scrubber (19) through a pipeline; the exhaust gas scrubber (19) is connected to an inert gas supply valve (17) through a pipeline; the inert gas supply valve (17) is connected to the top of the cargo hold (5) through a pipeline, The ammonia fuel supply system comprises: an ammonia fuel tank (1), a transfer pump (2), a primary booster pump (20), a secondary booster pump (14), a cylinder jacket water heater (15) and a ship main diesel engine (16). In the ammonia fuel supply system, the transfer pump (2) is installed at the bottom of the ammonia fuel tank (1), and the transfer pump (2) is connected to a primary booster pump (20) through a pipeline; the primary booster pump (20) is connected to a secondary booster pump (14) through a pipeline; the secondary booster pump (14) is connected to a cylinder jacket water heater (15) through a pipeline; and the cylinder jacket water heater (15) is connected to a main diesel engine (16) of the ship through a pipeline.

2. According to the ammonia-powered supertanker cargo hold unloading and inert gas replacement supply system as described in claim 1, it is characterized by: The ship's main diesel engine (16) passes part of the exhaust gas discharged into the exhaust gas collection unit, and then the exhaust gas in the exhaust gas collection unit is blown into the exhaust gas washing unit (19) through the fan (18).

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