A marine ammonia fuel supply system and method with a BOG treatment system

Abstract

The present invention discloses a marine ammonia fuel supply system and method with a BOG treatment system, which includes an ammonia fuel storage tank, a low-pressure pump, a first remote control valve, a second remote control valve, an ammonia fuel supply pipeline, and a BOG treatment pipeline. The low-pressure pump is arranged in the ammonia fuel storage tank, and the outlet of the low-pressure pump is connected to the input end of the ammonia fuel supply pipeline and one end of the first remote control valve. The output end of the ammonia fuel supply pipeline is connected to one end of the heat passage of the heat exchanger, and the other end of the heat passage of the heat exchanger is connected to one end of the second remote control valve. The other end of the first remote control valve is connected to the other end of the second remote control valve and one end of the cold passage of the BOG cooler. The input end of the BOG treatment pipeline is connected to the gas outlet of the ammonia fuel storage tank, and the output end of the BOG treatment pipeline is connected to the input end of the ammonia fuel supply pipeline. The present invention saves energy and reduces the generation of BOG in the ammonia fuel supply system at the same time.

Description

Technical Field

[0001] The present invention relates to an ammonia fuel supply system and method, in particular to a marine ammonia fuel supply system and method with a BOG treatment system, belonging to the technical field of ships. Background Art

[0002] As a carbon-free molecular fuel, ammonia burns to produce nitrogen and water, without carbon emission problems. Choosing ammonia as a zero-carbon fuel is an important future development trend.

[0003] Ammonia fuel is stored in a fully refrigerated liquid state on ships. The outer surface of the ammonia fuel storage tank is covered with a heat insulation layer. Although it can isolate heat to a certain extent, there is still a small amount of heat that causes a small amount of liquid ammonia to generate boil-off gas (BOG) through the insulation layer, resulting in an increase in the pressure of the ammonia fuel storage tank. In order to meet the requirements of the fuel inlet temperature and pressure of the ammonia fuel low-speed two-stroke main engine launched by MANN, it is necessary to configure an ammonia fuel supply system and a BOG treatment system to process the liquid ammonia fuel stored on the ship.

[0004] In the existing design, the marine ammonia fuel supply system does not reasonably process the refluxed liquid ammonia. The refluxed liquid ammonia may flow back into the ammonia fuel supply system or the ammonia fuel storage tank, which not only causes energy waste, but also exacerbates the gasification of liquid ammonia or the generation of BOG in the ammonia fuel storage tank, posing a safety hazard. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a marine ammonia fuel supply system and method with a BOG treatment system, which can save energy and reduce the generation of BOG in the ammonia fuel supply system.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is:

[0007] A marine ammonia fuel supply system with a BOG treatment system includes an ammonia fuel storage tank, a low-pressure pump, a first remote control valve, a second remote control valve, an ammonia fuel supply pipeline, and a BOG treatment pipeline. The low-pressure pump is arranged in the ammonia fuel storage tank, and the outlet of the low-pressure pump is connected to the input end of the ammonia fuel supply pipeline and one end of the first remote control valve. The ammonia fuel supply pipeline includes a heat exchanger, and the BOG treatment pipeline includes a BOG cooler. The output end of the ammonia fuel supply pipeline is connected to one end of the hot path of the heat exchanger, and the other end of the hot path of the heat exchanger is connected to one end of the second remote control valve. The other end of the first remote control valve is connected to the other end of the second remote control valve and one end of the cold path of the BOG cooler. The input end of the BOG treatment pipeline is connected to the gas outlet of the ammonia fuel storage tank, and the output end of the BOG treatment pipeline is connected to the input end of the ammonia fuel supply pipeline.

[0008] Further, liquid ammonia fuel at -33°C is stored in the ammonia fuel storage tank.

[0009] Further, the ammonia fuel supply pipeline further includes a high-pressure pump, a heat exchanger, a high-pressure heater, a main fuel inlet valve, a valve group unit, a main engine, and a main fuel return valve. One end of the high-pressure pump serves as the input end of the ammonia fuel supply pipeline, and the other end of the high-pressure pump is connected to one end of the cold passage of the heat exchanger. The other end of the cold passage of the heat exchanger is connected to one end of the cold passage of the high-pressure heater. The other end of the cold passage of the high-pressure heater is connected to one end of the main fuel inlet valve. The other end of the main fuel inlet valve is connected to the inlet of the valve group unit. The outlet of the valve group unit is connected to one end of the main fuel return valve. The other end of the main fuel return valve serves as the output end of the ammonia fuel supply pipeline. The valve group unit is connected to the main engine.

[0010] Further, the main engine adopts a MAN low-speed two-stroke main engine.

[0011] Further, the high-pressure heater heats the ammonia fuel to 25 - 45°C through an external heat source.

[0012] Further, the BOG treatment pipeline further includes a gas-liquid separation tank, a BOG compressor, and a buffer tank. The gas inlet of the gas-liquid separation tank serves as the input end of the BOG treatment pipeline. The gas outlet of the gas-liquid separation tank is connected to the inlet of the BOG compressor. The outlet of the BOG compressor is connected to one end of the hot passage of the BOG cooler. The other end of the hot passage of the BOG cooler is connected to the inlet of the buffer tank. The other end of the cold passage of the BOG cooler is connected to the inlet of the buffer tank. The liquid outlet of the buffer tank serves as the output end of the BOG treatment pipeline.

[0013] Further, a first one-way valve is provided on the connecting pipeline between the gas outlet of the ammonia fuel storage tank and the gas inlet of the gas-liquid separation tank, and a second one-way valve is provided on the connecting pipeline between the gas outlet of the buffer tank and the gas inlet of the gas-liquid separation tank. The first one-way valve and the second one-way valve prevent the gaseous ammonia in the gas-liquid separation tank from flowing backward out of the gas inlet of the gas-liquid separation tank.

[0014] A supply method of a marine ammonia fuel supply system with a BOG treatment system includes the following steps:

[0015] When the main engine is operating normally, the first remote control valve is closed and the second remote control valve is opened; the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank, and the liquid ammonia is pressurized by the high-pressure pump and enters the heat exchanger for preheating. The preheated liquid ammonia is then heated to 25-45°C by the high-pressure heater. The heated liquid ammonia passes through the fuel inlet main valve and the valve group unit and enters the main engine for combustion. The liquid ammonia refluxed from the valve group unit passes through the fuel reflux main valve and enters the heat exchanger as the heat source of the heat exchanger. The refluxed liquid ammonia after cooling enters the BOG cooler through the second remote control valve as the cold source of the BOG cooler. Finally, the refluxed liquid ammonia enters the cache tank for cache, and a part of the liquid ammonia in the cache tank is pumped out to the ammonia fuel supply pipeline by the high-pressure pump;

[0016] The gaseous ammonia vaporized in the ammonia fuel storage tank enters the gas-liquid separation tank from the gas outlet for gas-liquid separation. The separated gaseous ammonia enters the BOG compressor for compression and liquefaction. The liquefied liquid ammonia is cooled in the BOG cooler and sent to the buffer tank.

[0017] When the main engine stops working, the first remote control valve opens and the second remote control valve closes; the high-pressure pump does not work, and the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank. The liquid ammonia is sent to the BOG cooler through the first remote control valve as the cold source of the BOG cooler, and finally the reflux liquid ammonia enters the cache tank for cache.

[0018] Compared with the prior art, the present invention has the following advantages and effects: the present invention provides a marine ammonia fuel supply system and method with a BOG treatment system, which utilizes the waste heat of the reflux of the ammonia fuel main engine to preheat the ammonia fuel supply pipeline, thereby reducing the energy required for heating the main engine ammonia fuel, and at the same time, the liquid ammonia in the cooled reflux pipeline is used as a cooling medium for BOG, and the heated cooling medium enters the ammonia fuel supply pipeline through a buffer tank for heating, and the overall heat is always circulating in the ammonia fuel supply pipeline and the BOG treatment pipeline, and the liquid ammonia in the ammonia fuel storage tank is mainly used to supplement the loss in the system, and will not flow back to the ammonia fuel storage tank, thereby avoiding the storage tank temperature increase, thereby not causing the BOG generation speed in the ammonia fuel storage tank to accelerate, and the whole system design is reasonable and compact, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a marine ammonia fuel supply system with a BOG treatment system according to the present invention. DETAILED DESCRIPTION

[0020] In order to elaborate in detail on the technical solutions adopted by the present invention to achieve the intended technical purposes, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments. Moreover, without creative efforts, the technical means or technical features in the embodiments of the present invention can be replaced. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0021] As Figure 1 shown, a marine ammonia fuel supply system with a BOG treatment system according to the present invention includes an ammonia fuel storage tank 1, a low-pressure pump 2, a first remote control valve 3, a second remote control valve 4, an ammonia fuel supply pipeline, and a BOG treatment pipeline. The low-pressure pump 2 is arranged in the ammonia fuel storage tank 1, and the outlet of the low-pressure pump 2 is connected to the input end of the ammonia fuel supply pipeline and one end of the first remote control valve 3. The ammonia fuel supply pipeline includes a heat exchanger 6, and the BOG treatment pipeline includes a BOG cooler 14. The output end of the ammonia fuel supply pipeline is connected to one end of the heat path of the heat exchanger 6, and the other end of the heat path of the heat exchanger 6 is connected to one end of the second remote control valve 4. The other end of the first remote control valve 3 is connected to the other end of the second remote control valve 4 and one end of the cold path of the BOG cooler 14. The input end of the BOG treatment pipeline is connected to the gas outlet of the ammonia fuel storage tank 1, and the output end of the BOG treatment pipeline is connected to the input end of the ammonia fuel supply pipeline.

[0022] Among them, liquid ammonia fuel at -33°C is stored in the ammonia fuel storage tank 1.

[0023] The ammonia fuel supply pipeline further includes a high-pressure pump 5, a heat exchanger 6, a high-pressure heater 7, a fuel inlet main valve 8, a valve group unit 9, a main engine 10, and a fuel return main valve 11. One end of the high-pressure pump 5 serves as the input end of the ammonia fuel supply pipeline, the other end of the high-pressure pump 5 is connected to one end of the cold path of the heat exchanger 6, the other end of the cold path of the heat exchanger 6 is connected to one end of the cold path of the high-pressure heater 7, the other end of the cold path of the high-pressure heater 7 is connected to one end of the fuel inlet main valve 8, the other end of the fuel inlet main valve 8 is connected to the inlet of the valve group unit 9, the outlet of the valve group unit 9 is connected to one end of the fuel return main valve 11, the other end of the fuel return main valve 11 serves as the output end of the ammonia fuel supply pipeline, and the valve group unit 9 is connected to the main engine 10.

[0024] The main engine 10 adopts a MAN low-speed two-stroke main engine.

[0025] The high-pressure heater 7 heats the ammonia fuel to 25 - 45°C through an external heat source.

[0026] The BOG treatment pipeline also includes a gas-liquid separation tank 12, a BOG compressor 13, and a buffer tank 15. The inlet of the gas-liquid separation tank 12 serves as the input end of the BOG treatment pipeline. The outlet of the gas-liquid separation tank 12 is connected to the inlet of the BOG compressor. The outlet of the BOG compressor 13 is connected to one end of the hot path of the BOG cooler 14. The other end of the hot path of the BOG cooler 14 is connected to the inlet of the buffer tank 15. The other end of the cold path of the BOG cooler 14 is connected to the inlet of the buffer tank 15. The liquid outlet of the buffer tank serves as the output end of the BOG treatment pipeline.

[0027] A first one-way valve 16 is provided on the connecting pipeline between the outlet of the ammonia fuel storage tank 1 and the inlet of the gas-liquid separation tank 12. A second one-way valve 17 is provided on the connecting pipeline between the outlet of the buffer tank 15 and the inlet of the gas-liquid separation tank 12. The first one-way valve 16 and the second one-way valve 17 prevent the gaseous ammonia in the gas-liquid separation tank 12 from flowing backward out of the inlet of the gas-liquid separation tank 12.

[0028] A supply method of a marine ammonia fuel supply system with a BOG treatment system includes the following steps:

[0029] When the main engine is working normally, the first remote control valve is closed and the second remote control valve is opened; the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank. The liquid ammonia is pressurized by the high-pressure pump and then enters the heat exchanger for preheating. The preheated liquid ammonia is further heated to 25 - 45 °C by the high-pressure heater. The heated liquid ammonia enters the main engine for combustion after passing through the fuel inlet main valve and the valve group unit. The liquid ammonia flowing back from the valve group unit enters the heat exchanger as the heat source of the heat exchanger after passing through the fuel return main valve. The cooled returned liquid ammonia then enters the BOG cooler as the cold source of the BOG cooler through the second remote control valve. Finally, the returned liquid ammonia enters the buffer tank for buffering, and a part of the liquid ammonia in the buffer tank is pumped out by the high-pressure pump to the ammonia fuel supply pipeline.

[0030] The gaseous ammonia vaporized in the ammonia fuel storage tank enters the gas-liquid separation tank from the outlet for gas-liquid separation. The separated gaseous ammonia enters the BOG compressor for compression and liquefaction. The liquefied liquid ammonia is then cooled and sent to the buffer tank in the BOG cooler.

[0031] When the main engine stops working, the first remote control valve is opened and the second remote control valve is closed; the high-pressure pump does not work, and the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank. The liquid ammonia is sent to the BOG cooler as the cold source of the BOG cooler through the first remote control valve. Finally, the returned liquid ammonia enters the buffer tank for buffering.

[0032] The present invention provides a marine ammonia fuel supply system and method with a BOG treatment system, which utilizes waste heat from the reflux of an ammonia fuel main engine to preheat the ammonia fuel supply pipeline, thereby reducing the energy required for heating the main engine ammonia fuel. At the same time, the liquid ammonia in the cooled reflux pipeline is used as a cooling medium for BOG, and the heated cooling medium enters the ammonia fuel supply pipeline through a buffer tank for heating. The overall heat is constantly circulating in the ammonia fuel supply pipeline and the BOG treatment pipeline. The liquid ammonia in the ammonia fuel storage tank is mainly used to supplement the loss in the system, and will not flow back to the ammonia fuel storage tank, thereby avoiding an increase in the storage tank temperature, thereby not causing the BOG generation speed in the ammonia fuel storage tank to accelerate. The entire system is reasonably and compactly designed with low cost.

[0033] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A marine ammonia fuel supply system with a BOG treatment system, characterized in that: It includes an ammonia fuel storage tank, a low-pressure pump, a first remote control valve, a second remote control valve, an ammonia fuel supply pipeline, and a BOG treatment pipeline. The low-pressure pump is arranged in the ammonia fuel storage tank, and the outlet of the low-pressure pump is connected to the input end of the ammonia fuel supply pipeline and one end of the first remote control valve. The ammonia fuel supply pipeline includes a heat exchanger, and the BOG treatment pipeline includes a BOG cooler. The output end of the ammonia fuel supply pipeline is connected to one end of the heat path of the heat exchanger, and the other end of the heat path of the heat exchanger is connected to one end of the second remote control valve. The other end of the first remote control valve is connected to the other end of the second remote control valve and one end of the cold path of the BOG cooler. The input end of the BOG treatment pipeline is connected to the gas outlet of the ammonia fuel storage tank, and the output end of the BOG treatment pipeline is connected to the input end of the ammonia fuel supply pipeline; The ammonia fuel supply pipeline further includes a high-pressure pump, a heat exchanger, a high-pressure heater, a fuel inlet main valve, a valve group unit, a main engine, and a fuel return main valve. One end of the high-pressure pump serves as the input end of the ammonia fuel supply pipeline, the other end of the high-pressure pump is connected to one end of the cold path of the heat exchanger, the other end of the cold path of the heat exchanger is connected to one end of the cold path of the high-pressure heater, the other end of the cold path of the high-pressure heater is connected to one end of the fuel inlet main valve, the other end of the fuel inlet main valve is connected to the inlet of the valve group unit, the outlet of the valve group unit is connected to one end of the fuel return main valve, the other end of the fuel return main valve serves as the output end of the ammonia fuel supply pipeline, and the valve group unit is connected to the main engine; The BOG treatment pipeline further includes a gas-liquid separation tank, a BOG compressor, and a buffer tank. The gas inlet of the gas-liquid separation tank serves as the input end of the BOG treatment pipeline, the gas outlet of the gas-liquid separation tank is connected to the inlet of the BOG compressor, the outlet of the BOG compressor is connected to one end of the heat path of the BOG cooler, the other end of the heat path of the BOG cooler is connected to the inlet of the buffer tank, the other end of the cold path of the BOG cooler is connected to the inlet of the buffer tank, and the liquid outlet of the buffer tank serves as the output end of the BOG treatment pipeline; A first one-way valve is arranged on the connecting pipeline between the gas outlet of the ammonia fuel storage tank and the gas inlet of the gas-liquid separation tank, and a second one-way valve is arranged on the connecting pipeline between the gas outlet of the buffer tank and the gas inlet of the gas-liquid separation tank. The first one-way valve and the second one-way valve prevent the gaseous ammonia in the gas-liquid separation tank from flowing back out from the gas inlet of the gas-liquid separation tank; When the main engine is working normally, the first remote control valve is closed and the second remote control valve is opened; the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank, the liquid ammonia is pressurized by the high-pressure pump and then enters the heat exchanger for preheating, the preheated liquid ammonia is further heated to 25 - 45 °C by the high-pressure heater, the heated liquid ammonia enters the main engine for combustion after passing through the fuel inlet main valve and the valve group unit, the liquid ammonia refluxed by the valve group unit enters the heat exchanger as the heat source of the heat exchanger after passing through the fuel return main valve, the cooled reflux liquid ammonia enters the BOG cooler as the cold source of the BOG cooler through the second remote control valve, and finally the reflux liquid ammonia enters the buffer tank for buffering. A part of the liquid ammonia in the buffer tank is pumped out by the high-pressure pump to the ammonia fuel supply pipeline; The gaseous ammonia vaporized in the ammonia fuel storage tank enters the gas-liquid separation tank from the gas outlet for gas-liquid separation. The separated gaseous ammonia enters the BOG compressor for compression and liquefaction. The liquefied liquid ammonia is then cooled and temperature-reduced in the BOG cooler and sent to the buffer tank. When the main engine stops working, the first remote control valve opens and the second remote control valve closes. The high-pressure pump does not work, and the low-pressure pump pumps out the liquid ammonia in the ammonia fuel storage tank. The liquid ammonia is sent through the first remote control valve to the BOG cooler as the cold source of the BOG cooler, and finally the returned liquid ammonia enters the buffer tank for buffering.

2. The marine ammonia fuel supply system with a BOG treatment system according to claim 1, characterized in that: The ammonia fuel storage tank stores liquid ammonia fuel at -33°C.

3. The marine ammonia fuel supply system with a BOG treatment system according to claim 1, characterized in that: The main engine uses a MAN low-speed two-stroke main engine.

4. A marine ammonia fuel supply system with a BOG treatment system according to claim 1, characterized in that: The high-pressure heater heats the ammonia fuel to 25 - 45°C through an external heat source.

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