A nitrogen circulation system for a fuel tank on a ship

Abstract

The utility model discloses a shipborne fuel tank nitrogen circulation system, including fuel tank, nitrogen cylinder, air compressor, nitrogen circulation pipeline and gas injection pipeline, the fuel tank is loaded with bio -diesel or bio -mixed fuel, and the nitrogen outlet is set up above fuel liquid level in fuel tank top, and the nitrogen inlet is arranged to fuel liquid level above and below in fuel tank lateral wall, and the air compressor's air inlet and exhaust port are respectively linked with first remote control three -way valve and second remote control three -way valve, and the first air inlet of first remote control three -way valve is linked with the air outlet of nitrogen cylinder, and the first air inlet of second remote control three -way valve is linked with the first air inlet of nitrogen cylinder, and the nitrogen circulation pipeline links the first air inlet of first remote control three -way valve with nitrogen outlet, and the gas injection pipeline links the second air outlet of second remote control three -way valve with two nitrogen inlets. The utility model's advantage lies in being able to inhibit the oxidation metamorphic of shipborne bio -fuel, reduces the bio -fuel corrosion pipeline and equipment risk.

Description

Technical Field

[0001] This utility model relates to the field of ship design technology, and in particular to a shipborne fuel tank nitrogen circulation system. Background Technology

[0002] Biodiesel refers to fatty acid methyl esters or ethyl esters formed by the esterification reaction of vegetable oil, animal oil, waste oil, or microbial oil with methanol or ethanol. Bioblended fuels refer to fuels blended with traditional fossil fuels. Biodiesel is a drop-in renewable green energy source, and its use is an important method for achieving net-zero emissions in the shipping industry.

[0003] Traditional fossil fuels are relatively stable, and their quality is generally not affected by oxygen or moisture during storage.

[0004] The unsaturated fatty acid methyl esters in biodiesel are highly susceptible to oxidative decomposition. This oxidation releases fatty acids and water, further accelerating the biodiesel's oxidative breakdown. The fatty acids also corrode pipelines and equipment, while the water promotes microbial growth. The accumulation of microbial sludge can clog filters.

[0005] In addition to the water produced by the oxidation and decomposition of biodiesel, the fuel tank itself draws in outside air through vents during storage due to diurnal temperature variations and fuel consumption. Since sea air is saturated with water vapor, this water vapor condenses and liquefies upon entering the fuel tank, adding extra moisture to the tank.

[0006] Biodiesel itself has a relatively strong water-soluble capacity, attracting and retaining moisture. However, considering its low thermal and oxidative stability, overheating of biodiesel should be avoided.

[0007] Therefore, it is necessary to inhibit the oxidative decomposition of biodiesel in order to ensure the quality of biofuels and protect pipelines and equipment.

[0008] Patent No. CN201920878556.9 invented a device for removing oxygen from cold water by aerating it with nitrogen. This device is only used for deoxygenation, requires manual operation, and the nitrogen is for single use only, making it unsuitable for use in large biodiesel / bioblended fuel tanks on ships.

[0009] Currently, biodiesel has not been widely used in ships, and there is no water and oxygen removal system specifically designed for biofuel and bio-blended fuel tanks in existing fuel tank designs. Utility Model Content

[0010] The purpose of this invention is to provide a nitrogen circulation system for shipboard fuel tanks that can inhibit the oxidation and deterioration of shipboard biofuels, extend the shelf life of biofuels, and reduce the risk of biofuel corrosion of pipelines and equipment.

[0011] The above-mentioned technical objective of this utility model is achieved through the following technical solution: A marine fuel tank nitrogen circulation system, characterized in that it includes a fuel tank, a nitrogen cylinder, an air compressor, a nitrogen circulation pipeline, and a gas injection pipeline. The fuel tank is loaded with biodiesel or bio-blended fuel. A nitrogen outlet is provided on the top of the fuel tank above the fuel liquid surface. Nitrogen inlets are provided on the side walls of the fuel tank above and below the fuel liquid surface. The air compressor's inlet and outlet are respectively connected to a first remote-controlled three-way valve and a second remote-controlled three-way valve. The first inlet of the first remote-controlled three-way valve is connected to the outlet of the nitrogen cylinder, and the first outlet of the second remote-controlled three-way valve is connected to the first inlet of the nitrogen cylinder. The second inlet of the nitrogen cylinder is also connected to a nitrogen source. The nitrogen circulation pipeline connects the first inlet of the first remote-controlled three-way valve to the nitrogen outlet. The gas injection pipeline connects the second outlet of the second remote-controlled three-way valve to two sets of nitrogen inlets.

[0012] Preferably, the nitrogen circulation pipeline is sequentially connected to an exhaust fan, an oil mist coarse filter, a gas-liquid separator, and an oil-water filter along the nitrogen flow direction.

[0013] Preferably, the gas-liquid separator is further provided with a liquid cooling pipeline for gas cooling. The liquid cooling pipeline is provided with a cooling seawater inlet and a cooling seawater outlet, and a solenoid valve is provided at the cooling seawater inlet and the cooling seawater outlet.

[0014] Preferably, the top of the fuel tank is also connected to a vacuum pressure relief valve for controlling the internal pressure of the fuel tank.

[0015] Preferably, a humidity sensor, an oxygen concentration sensor, and a pressure sensor are also installed on the top of the fuel tank above the fuel level.

[0016] Preferably, a moisture sensor is also provided on the side wall of the fuel tank below the fuel level.

[0017] Preferably, the gas injection pipeline is further provided with a third remote-controlled three-way valve that is connected to two sets of nitrogen inlets respectively.

[0018] Preferably, it also includes an external control unit, which controls the first remote-controlled three-way valve, the second remote-controlled three-way valve, the third remote-controlled three-way valve, the exhaust fan, and the air compressor by acquiring signals from the humidity sensor, the oxygen concentration sensor, the pressure sensor, and the moisture sensor.

[0019] Preferably, an aeration pipe is provided at the bottom of the fuel tank below the fuel liquid level, and the aeration pipe is connected to a gas injection pipeline.

[0020] Preferably, the bottom of the fuel tank is also provided with a bilge water drain.

[0021] In summary, this utility model has the following beneficial effects: 1. This utility model achieves precise pressure control of the fuel tank by incorporating a pressure sensor and a nitrogen circulation pipeline. Specifically, during normal system operation, when the pressure inside the tank increases, the air compressor redirects some nitrogen from the nitrogen circulation pipeline back to the nitrogen cylinder; when the pressure inside the tank decreases, nitrogen from the nitrogen cylinder is redirected into the nitrogen circulation pipeline. Through this pressure control process, the vacuum pressure valve remains inactive during normal system operation, avoiding the additional moisture from the outside air introduced by the conventional free-flowing ventilation method of fuel tanks.

[0022] 2. This utility model improves the nitrogen reuse rate and reduces the daily consumption of circulating nitrogen by setting up a nitrogen recovery pipeline to adapt to the pressure changes caused by the diurnal temperature difference in the fuel tank.

[0023] 3. This invention increases the aeration area of ​​biofuel by introducing dry nitrogen from the bottom of the tank and forming floating bubbles, compared to the ordinary method of only drying the air inside the tank. This increases the evaporation rate of water in the biofuel and also plays a stirring role. It can reduce the problem of uneven biofuel composition caused by the condensation of bio-oils and low-temperature condensation of waxes in biodiesel or bio-blended diesel that has been stagnant for a long time. Compared to the ordinary method of heating the fuel inside the tank to evaporate water, it avoids the overheating of biofuel. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a shipborne fuel tank nitrogen circulation system according to this utility model; Figure 2 This is a schematic diagram of the external control unit of this utility model; In the diagram: 1-Fuel tank, 2-Nitrogen cylinder, 3-Air compressor, 4-Nitrogen circulation pipeline, 5-Gas injection pipeline, 6-First remote control three-way valve, 7-Second remote control three-way valve, 8-Nitrogen inlet, 9-Nitrogen outlet, 10-Exhaust fan, 11-Oil mist coarse filter, 12-Gas-liquid separator, 13-Oil-water filter, 14-Liquid cooling pipeline, 15-Solenoid valve, 16-Vacuum pressure relief valve, 17-Humidity sensor, 18-Oxygen concentration sensor, 19-Pressure sensor, 20-Moisture sensor, 21-Third remote control three-way valve, 22-Aeration pipe, 23-Bottom water drain. Detailed Implementation

[0025] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on this utility model.

[0026] like Figure 1 and 2 The illustrated marine fuel tank nitrogen circulation system includes a fuel tank 1, a nitrogen cylinder 2, an air compressor 3, a nitrogen circulation pipeline 4, and a gas injection pipeline 5. The fuel tank 1 is loaded with biodiesel or bio-blended fuel. A nitrogen outlet 9 is provided on the top of the fuel tank 1 above the fuel liquid surface. Nitrogen inlets 8 are provided on the side wall of the fuel tank 1 above and below the fuel liquid surface. The air compressor 3's air inlet and exhaust outlet are respectively connected to a first remote-controlled three-way valve 6 and a second remote-controlled three-way valve 7. The first air inlet of the first remote-controlled three-way valve 6 is connected to the air outlet of the nitrogen cylinder 2, and the first air outlet of the second remote-controlled three-way valve 7 is connected to the first air inlet of the nitrogen cylinder 2. The second air inlet of the nitrogen cylinder 2 is also connected to a nitrogen source. The nitrogen circulation pipeline 4 connects the first air inlet of the first remote-controlled three-way valve 6 to the nitrogen outlet 9. The gas injection pipeline 5 connects the second air outlet of the second remote-controlled three-way valve 7 to the two sets of nitrogen inlets 8.

[0027] Along the direction of nitrogen flow, the nitrogen circulation pipeline 4 is connected to a blower 10, an oil mist coarse filter 11, a gas-liquid separator 12, and an oil-water filter 13.

[0028] The gas-liquid separator 12 is also equipped with a liquid cooling pipeline 14 for gas cooling. The liquid cooling pipeline 14 is respectively equipped with a cooling seawater inlet and a cooling seawater outlet, and a solenoid valve 15 is installed at the cooling seawater inlet and the cooling seawater outlet.

[0029] The top of the fuel tank 1 is also connected to a vacuum pressure relief valve 16 for controlling the internal pressure of the fuel tank 1.

[0030] A humidity sensor 17, an oxygen concentration sensor 18, and a pressure sensor 19 are installed on the top of the fuel tank 1 above the fuel liquid surface. A moisture sensor 20 is also installed on the side wall of the fuel tank 1 below the fuel liquid surface to monitor the internal environment of the fuel tank 1.

[0031] The gas injection pipeline 5 is also equipped with a third remote-controlled three-way valve 21, which is connected to two sets of nitrogen inlets 8 respectively.

[0032] It also includes an external control unit, which controls the first remote-controlled three-way valve 6, the second remote-controlled three-way valve 7, the third remote-controlled three-way valve 21, the exhaust fan 10 and the air compressor 3 by acquiring signals from the humidity sensor 17, the oxygen concentration sensor 18, the pressure sensor 19 and the moisture sensor 20.

[0033] An aeration pipe 22 is installed at the bottom of the fuel tank 1 below the fuel liquid level, and the aeration pipe 22 is connected to the gas injection pipeline 5.

[0034] The bottom of fuel tank 1 is also equipped with a bilge water drain outlet 23.

[0035] The working principle of this utility model is as follows: Initial nitrogen filling: Nitrogen cylinder 2 is connected to nitrogen circulation pipeline 4 via the first remote-controlled three-way valve 6 at the inlet of air compressor 3. The nitrogen then passes through air compressor 3 and gas injection pipeline 5, entering nitrogen inlet 8 at the top of fuel tank 1 to inert the fuel tank with nitrogen. Once oxygen concentration sensor 18 reports that the oxygen concentration has dropped to a predetermined value, nitrogen cylinder 2 disconnects, stopping the supply of nitrogen to nitrogen circulation pipeline 4.

[0036] Water removal: When the value reported by either the moisture sensor 20 or the humidity sensor 17 in fuel tank 1 is higher than a preset value, the external control unit activates the exhaust fan 10, air compressor 3, and air-cooled gas-liquid separator 12, and connects the cooling seawater pipeline and the first remote-controlled three-way valve 6. The nitrogen containing moisture in fuel tank 1 is extracted by the exhaust fan, passes sequentially through the oil mist coarse filter 11, the air-cooled gas-liquid separator 12, and the oil-water filter 13 to remove moisture, and then passes through the air compressor 3 and the gas injection pipeline 5 into the nitrogen inlet 8 at the top of fuel tank 1, completing the nitrogen circulation. When the values ​​reported by both the moisture sensor 20 and the humidity sensor 17 are lower than the set values, the external control unit closes the inlet and outlet valves of the exhaust fan 10, air compressor 3, and nitrogen circulation pipeline 4.

[0037] High pressure control: When the pressure inside fuel tank 1 exceeds the set general high pressure value, the external control unit activates the exhaust fan 10 and air compressor 3, and controls the first remote-controlled three-way valve 6 to extract nitrogen from fuel tank 1. The nitrogen then passes sequentially through an oil mist coarse filter 11, an air-cooled gas-liquid separator 12, and an oil-water filter 13. Finally, it is compressed by the air compressor 3, passed through the second remote-controlled three-way valve 7, and stored in nitrogen cylinder 2. This process continues until the pressure inside fuel tank 1 falls below the set general high pressure value. When the pressure inside fuel tank 1 reaches or exceeds the safety set high pressure value (exceeding the general high pressure value), the vacuum pressure relief valve 16 automatically activates, releasing the nitrogen from fuel tank 1 directly into the atmosphere to relieve pressure.

[0038] Low pressure control: When the pressure inside fuel tank 1 falls below the set low pressure value, the second remote-controlled three-way valve 7 and the third remote-controlled three-way valve 21 are controlled by the external control unit to connect nitrogen cylinder 2 to fuel tank 1. Nitrogen is then supplied to fuel tank 1 through aeration pipe 22 until the pressure inside fuel tank 1 exceeds the set low pressure value. When the pressure inside fuel tank 1 reaches or falls below the safe low pressure value (below the normal low pressure value), the nitrogen circulation system is considered to have malfunctioned. In this case, vacuum pressure relief valve 16 automatically activates to directly supply external atmosphere into fuel tank 1 to restore pressure.

[0039] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Those skilled in the art can make various modifications or equivalent substitutions to the present utility model within its substance and protection scope, and such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present utility model's technical solution.

Claims

1. A marine fuel tank nitrogen recirculation system, characterized in that, The system includes a fuel tank, a nitrogen cylinder, an air compressor, a nitrogen circulation pipeline, and a gas injection pipeline. The fuel tank is filled with biodiesel or bio-blended fuel. A nitrogen outlet is located on the top of the fuel tank above the fuel level. Nitrogen inlets are located on the side walls of the fuel tank above and below the fuel level. The air compressor's inlet and outlet are respectively connected to a first remote-controlled three-way valve and a second remote-controlled three-way valve. The first inlet of the first remote-controlled three-way valve is connected to the outlet of the nitrogen cylinder, and the first outlet of the second remote-controlled three-way valve is connected to the first inlet of the nitrogen cylinder. The second inlet of the nitrogen cylinder is also connected to a nitrogen source. The nitrogen circulation pipeline connects the first inlet of the first remote-controlled three-way valve to the nitrogen outlet. The gas injection pipeline connects the second outlet of the second remote-controlled three-way valve to the two sets of nitrogen inlets.

2. The shipborne fuel tank nitrogen recirculation system according to claim 1, characterized in that: The nitrogen circulation pipeline is sequentially connected to an exhaust fan, an oil mist coarse filter, a gas-liquid separator, and an oil-water filter along the direction of nitrogen flow.

3. A shipboard fuel tank nitrogen recirculation system according to claim 2, characterized in that: The gas-liquid separator is also equipped with a liquid cooling pipeline for gas cooling. The liquid cooling pipeline is respectively provided with a cooling seawater inlet and a cooling seawater outlet, and a solenoid valve is provided at the cooling seawater inlet and the cooling seawater outlet.

4. A shipboard fuel tank nitrogen recirculation system according to claim 1, characterized in that: The top of the fuel tank is also connected to a vacuum pressure relief valve that controls the internal pressure of the fuel tank.

5. A shipboard fuel tank nitrogen recirculation system according to claim 2, characterized in that: A humidity sensor, an oxygen concentration sensor, and a pressure sensor are also installed on the top of the fuel tank above the fuel level.

6. A shipboard fuel tank nitrogen recirculation system according to claim 5, characterized in that: A moisture sensor is also installed on the side wall of the fuel tank below the fuel level.

7. A shipboard fuel tank nitrogen recirculation system according to claim 6, characterized in that: The gas injection pipeline is also equipped with a third remote-controlled three-way valve that is connected to two sets of nitrogen inlets.

8. A shipboard fuel tank nitrogen recirculation system according to claim 7, characterized in that: It also includes an external control unit, which controls a first remote-controlled three-way valve, a second remote-controlled three-way valve, a third remote-controlled three-way valve, an exhaust fan, and an air compressor by acquiring signals from a humidity sensor, an oxygen concentration sensor, a pressure sensor, and a moisture sensor.

9. A shipboard fuel tank nitrogen recirculation system according to claim 1, characterized in that: An aeration pipe is installed at the bottom of the fuel tank below the fuel liquid level, and the aeration pipe is connected to a gas injection pipeline.

10. A shipboard fuel tank nitrogen recirculation system according to claim 1, characterized in that: The bottom of the fuel tank is also equipped with a bilge water drain.

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