An LNG ship filling system and method based on BOG reliquefaction

Abstract

The application provides a LNG ship filling system and method based on BOG reliquefaction, and relates to the technical field of clean energy. The filling system comprises a LNG power ship storage tank, a LNG ship filling device and a BOG reliquefaction device. The outlet of the LNG ship filling device is communicated with the liquid inlet of the LNG power ship storage tank. The BOG reliquefaction device comprises a heat exchanger, a pressure stabilizing tank, a gas-liquid separation tank, a vaporizer, a self-pressurizing heat exchanger and a liquid outlet valve. The gas outlet of the heat exchanger is communicated with the first end of a first pipeline. The vaporizer is connected in series on the first pipeline. The liquid outlet of the heat exchanger is communicated with the liquid inlet of the gas-liquid separation tank through a second pipeline. By using multiple tank cars to simultaneously fill the medium and large LNG ships, the BOG generated during the filling period is liquefied and recovered by using the heat exchanger, the pressure stabilizing tank, the gas-liquid separation tank and other equipment and is refilled. Compared with the existing LNG filling system, the LNG ship filling system has the advantages of simple structure, high filling efficiency, high reliability and strong practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clean energy, and particularly relates to an LNG ship filling system and method based on BOG reliquefaction. BACKGROUND

[0002] The current global emission reduction and low-carbon trend has pushed the shipping industry to the forefront, and various countries have explored alternative energy. LNG, as a clean and low-carbon energy source, has won the opportunity in energy replacement. In the field of ships, LNG and other clean fuels are used to replace traditional fuels, and the supply of clean energy in the transportation industry is strengthened. The development of LNG fuel-powered ships has ushered in a historic opportunity.

[0003] LNG is condensed into a liquid by cooling natural gas in a gaseous state at normal pressure to -162 DEG C, with a volume of 1 / 625 of the gaseous state, which can greatly save storage and transportation space and cost, and has the characteristics of high heat value and high performance. Compared with diesel, it can reduce 90% of nitrogen oxide emissions and 100% of sulfur and particulate matter emissions.

[0004] Similar to refueling, LNG-powered ship fuel needs to be refueled. The current common refueling methods are single-tank truck refueling, shore-based station refueling, and ship-to-ship refueling. The single-tank truck refueling method has a low refueling rate, and the shore-based station refueling and ship-to-ship refueling methods have high investment and long cycles, which cannot meet the refueling needs of medium and large ships in the short term. In addition, LNG is stored at normal pressure and -162 DEG C low temperature. Due to heat leakage of the storage tank, pipeline, and equipment operation, a large amount of BOG is generated during precooling and refueling of the LNG-powered ship, which causes the system pressure to rise and causes safety hazards. Direct emptying not only causes economic losses, but also has adverse effects on the environment, and the BOG needs to be recovered and treated. SUMMARY

[0005] The present application provides a LNG ship filling system based on BOG reliquefaction, which solves the problem of low refueling efficiency and inability to recover and treat BOG in the prior art.

[0006] The present application provides a LNG ship filling system based on BOG reliquefaction, which solves the problem of low refueling efficiency and inability to recover and treat BOG in the prior art.

[0007] LNG-powered ship storage tank;

[0008] LNG ship filling device, the outlet of the LNG ship filling device is in communication with the liquid inlet of the LNG-powered ship storage tank;

[0009] The BOG reliquefaction device comprises a heat exchanger, a pressure stabilizing tank, a gas-liquid separation tank, a vaporizer, a self-pressurizing heat exchanger and a liquid outlet valve, the gas outlet of the heat exchanger is communicated with the first end of a first pipeline, the vaporizer is connected in series on the first pipeline, and the liquid outlet of the heat exchanger is communicated with the liquid inlet of the gas-liquid separation tank through a second pipeline; the gas outlet of the pressure stabilizing tank is communicated with the gas inlet of the heat exchanger through a third pipeline, and the gas inlet of the pressure stabilizing tank is communicated with the gas outlet of the LNG power ship storage tank; the gas outlet of the gas-liquid separation tank is communicated with the third pipeline, the liquid outlet of the gas-liquid separation tank is communicated with the liquid inlet of a first tank car through a fourth pipeline, and the liquid outlet valve is arranged on the fourth pipeline; the liquid inlet of the self-pressurizing heat exchanger is communicated with the liquid outlet of the gas-liquid separation tank, and the liquid outlet of the self-pressurizing heat exchanger is communicated with the gas inlet of the gas-liquid separation tank.

[0010] The liquid nitrogen storage device is communicated with the liquid inlet of the heat exchanger through a fifth pipeline.

[0011] According to the LNG ship filling system based on BOG reliquefaction provided by the embodiment of the present application, the liquid nitrogen storage device comprises:

[0012] A liquid nitrogen storage tank, and a first liquid outlet of the liquid nitrogen storage tank is communicated with the liquid inlet of the heat exchanger through the fifth pipeline.

[0013] A booster, a liquid inlet of the booster is communicated with a second liquid outlet of the liquid nitrogen storage tank, and a gas outlet of the booster is communicated with a gas inlet of the liquid nitrogen storage tank.

[0014] A first booster valve is arranged on the liquid inlet of the booster.

[0015] According to the LNG ship filling system based on BOG reliquefaction provided by the embodiment of the present application, the BOG reliquefaction device further comprises:

[0016] A liquid nitrogen inlet valve is arranged on the fifth pipeline.

[0017] A regulating valve is arranged on the fifth pipeline between the liquid nitrogen inlet valve and the heat exchanger.

[0018] A pressure sensor is arranged on the fifth pipeline between the regulating valve and the heat exchanger and is electrically connected with the regulating valve.

[0019] According to the LNG ship filling system based on BOG reliquefaction provided by the embodiment of the present application, the BOG reliquefaction device further comprises:

[0020] A gas-liquid separation tank inlet valve is arranged on the second pipeline.

[0021] The BOG reliquefaction device further comprises:

[0022] A temperature sensor is arranged on the first pipeline between the heat exchanger and the vaporizer.

[0023] A pressure stabilizing tank outlet valve is arranged on the third pipeline and electrically connected with the temperature sensor.

[0024] The BOG reliquefaction device further comprises:

[0025] A liquid level meter is arranged in the gas-liquid separation tank, and the liquid level meter is electrically connected with the liquid outlet valve.

[0026] A second booster valve is arranged at the inlet of the self-boosting heat exchanger.

[0027] The LNG ship filling device comprises:

[0028] An LNG filling main pipe, one end of the LNG filling main pipe being communicated with the liquid inlet of the LNG power ship storage tank;

[0029] At least one LNG ship filling assembly, the LNG ship filling assembly comprising an LNG submersible pump, a submersible pump outlet valve, a booster vaporizer, a booster liquid phase valve, a booster gas phase valve, a check valve, a booster port, a gas phase port and a liquid phase port, the liquid outlet of the LNG submersible pump being communicated with the other end of the LNG filling main pipe through a branch, the submersible pump outlet valve being arranged on the branch, the liquid inlet of the LNG submersible pump being communicated with the liquid phase port through a liquid inlet pipe, the check valve being arranged on the liquid inlet pipe; the gas return port of the LNG submersible pump being communicated with the gas phase port through a gas return pipe, the booster gas phase valve being arranged on the gas return pipe; the booster port being communicated with the inlet of the booster liquid phase valve, the outlet of the booster liquid phase valve being communicated with the inlet of the booster vaporizer, the outlet of the booster vaporizer being communicated with the gas return pipe between the booster gas phase valve and the LNG submersible pump.

[0030] The LNG ship filling device further comprises:

[0031] A submersible pump gas phase valve is arranged on the gas return pipe between the booster gas phase valve and the LNG submersible pump.

[0032] A submersible pump inlet valve is arranged on the liquid inlet pipe between the LNG submersible pump and the check valve.

[0033] The application further provides an LNG ship filling method based on BOG reliquefaction, which is based on any one of the LNG ship filling methods based on BOG reliquefaction and comprises the following steps:

[0034] The LNG in the second tank truck is delivered to the supercharged vaporizer through the supercharging port to exchange heat with air to generate BOG;

[0035] The generated BOG is delivered to the second tank truck through the gas phase port to increase the pressure in the second tank truck;

[0036] The LNG in the second tank truck is delivered to the LNG submersible pump through the liquid phase port under the drive of the pressure, and the LNG is pumped to the LNG power ship storage tank through the LNG submersible pump;

[0037] The BOG in the LNG power ship storage tank enters the pressure stabilizing tank and then enters the heat exchanger;

[0038] The liquid nitrogen output by the liquid nitrogen storage device enters the heat exchanger to exchange heat with the BOG, so that the BOG is liquefied to obtain LNG;

[0039] The liquefied LNG enters the gas-liquid separation tank and is delivered to the first tank truck after reaching a predetermined amount.

[0040] According to the LNG ship filling method based on BOG reliquefaction provided by the embodiment of the application, while the step of delivering the liquefied LNG to the gas-liquid separation tank and delivering the LNG to the first tank truck after reaching a predetermined amount is performed, the filling method further comprises the following steps:

[0041] The unliquefied BOG in the gas-liquid separation tank is delivered to the heat exchanger to be condensed.

[0042] The LNG ship filling system based on BOG reliquefaction provided by the embodiment of the application has the advantages of simple structure, high filling efficiency, high reliability and strong practicability by simultaneously filling a plurality of tank trucks to a large LNG ship, and recycling and refilling the BOG generated during filling by using the heat exchanger, the pressure stabilizing tank and the gas-liquid separation tank. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0044] Figure 1 is a structural schematic diagram of the LNG ship filling system based on BOG reliquefaction provided by the embodiment of the present application.

[0045] Reference signs:

[0046] 1, liquid nitrogen storage tank; 2, BOG reliquefaction device; 3, booster; 4, LNG power ship storage tank; 5, second tank car; 6, LNG ship filling device; 7, LNG submersible pump; 8, submersible pump outlet valve; 9, submersible pump gas phase valve; 10, submersible pump inlet valve; 11, pressurized vaporizer; 12, pressurized port; 13, gas phase port; 14, liquid phase port; 15, pressurized liquid phase valve; 16, pressurized gas phase valve; 17, check valve; 18, liquid nitrogen inlet valve; 19, heat exchanger; 20, pressure stabilizing tank outlet valve; 21, vaporizer; 22, nitrogen exhaust valve; 23, gas-liquid separation tank inlet valve; 24, self-pressurized heat exchanger; 25, second pressurized valve; 26, liquid outlet valve; 27, regulating valve; 28, pressure stabilizing tank; 29, flow meter; 30, gas-liquid separation tank; 31, first pipeline; 32, second pipeline; 33, third pipeline; 34, fourth pipeline; 35, fifth pipeline; 36, gas return pipe; 37, liquid inlet pipe; 38, first tank car; 39, first pressurized valve. DETAILED DESCRIPTION

[0047] The embodiments of the present application will be further described below in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0048] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0049] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0050] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature is "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only means that the first feature is higher than the second feature in horizontal height. The first feature is "under", "below" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only means that the first feature is lower than the second feature in horizontal height.

[0051] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0052] The specific structure and working principle of the LNG ship filling system based on BOG reliquefaction provided by the embodiments of the present application are described below. Figure 1 The specific structure and working principle of the LNG ship filling system based on BOG reliquefaction provided by the embodiments of the present application are described below.

[0053] Figure 1 The structure schematic diagram of the LNG ship filling system based on BOG reliquefaction provided by the embodiments of the present application is illustrated, as shown in Figure 1As shown, the LNG ship refueling system based on BOG reliquefaction comprises an LNG power ship storage tank 4, an LNG ship refueling device 6, a BOG reliquefaction device 2 and a liquid nitrogen storage device, an outlet of the LNG ship refueling device 6 is communicated with a liquid inlet of the LNG power ship storage tank 4. The BOG reliquefaction device 2 comprises a heat exchanger 19, a pressure stabilizing tank 28, a gas-liquid separation tank 30, a vaporizer 21, a self-pressurizing heat exchanger 24 and a liquid outlet valve 26, a gas outlet of the heat exchanger 19 is communicated with a first end of a first pipeline 31, the vaporizer 21 is connected in series on the first pipeline 31, a liquid outlet of the heat exchanger 19 is communicated with a liquid inlet of the gas-liquid separation tank 30 through a second pipeline 32; a gas outlet of the pressure stabilizing tank 28 is communicated with a gas inlet of the heat exchanger 19 through a third pipeline 33, a gas inlet of the pressure stabilizing tank 28 is communicated with a gas outlet of the LNG power ship storage tank 4; a gas outlet of the gas-liquid separation tank 30 is communicated with the third pipeline 33, a liquid outlet of the gas-liquid separation tank 30 is communicated with a liquid inlet of a first tank truck 38 through a fourth pipeline 34, the liquid outlet valve 26 is arranged on the fourth pipeline 34; an inlet of the self-pressurizing heat exchanger 24 is communicated with the liquid outlet of the gas-liquid separation tank 30, an outlet of the self-pressurizing heat exchanger 24 is communicated with the gas inlet of the gas-liquid separation tank 30; a liquid outlet of the liquid nitrogen storage device is communicated with the liquid inlet of the heat exchanger 19 through a fifth pipeline 35.

[0054] The LNG ship refueling system based on BOG reliquefaction provided by the embodiment of the present application has the advantages of simple structure, high refueling efficiency, high reliability and strong practicability compared with the existing LNG refueling system.

[0055] In an embodiment of the present application, the heat exchanger 19 is a shell-and-tube heat exchanger, the heat exchanger 19 is used for heat exchange between the liquid nitrogen output by the liquid nitrogen storage device and the BOG in the heat exchanger 19, so that the BOG is liquefied to form LNG. The pressure stabilizing tank 28 is used for temporarily storing the BOG input by the LNG power ship storage tank 4, and ensuring the stable gas flow of the BOG in the recycling process. The gas-liquid separation tank 30 is used for inputting the liquid LNG into the first tank truck 38, and transporting the unliquefied BOG to the heat exchanger 19 for condensation. The vaporizer 21 is used for increasing the temperature of the nitrogen gas formed by gasification to normal temperature, and discharging through the nitrogen gas exhaust valve 22 or used for pipeline purging.

[0056] In an embodiment of the present application, the liquid nitrogen storage device comprises a liquid nitrogen storage tank 1, a booster 3 and a first booster valve 39, a first liquid outlet of the liquid nitrogen storage tank 1 is communicated with the liquid inlet of the heat exchanger 19 through the fifth pipeline 35. The liquid inlet of the booster 3 is communicated with a second liquid outlet of the liquid nitrogen storage tank 1, the gas outlet of the booster 3 is communicated with the gas inlet of the liquid nitrogen storage tank 1, and the first booster valve 39 is arranged on the liquid inlet of the booster 3.

[0057] The liquid nitrogen storage tank 1 is used for storing liquid nitrogen, and the booster 3 is used for gasifying the liquid nitrogen in the liquid nitrogen storage tank 1 and then conveying the gasified liquid nitrogen into the liquid nitrogen storage tank 1 to increase the internal pressure of the liquid nitrogen storage tank 1 when the internal pressure of the liquid nitrogen storage tank 1 is insufficient. The first booster valve 39 is used for opening when the internal pressure of the liquid nitrogen storage tank 1 is lower than a preset value, so that the liquid nitrogen in the liquid nitrogen storage tank 1 enters the booster 3 for gasification, and the first booster valve 39 is closed when the internal pressure of the liquid nitrogen storage tank 1 reaches the preset value.

[0058] In an embodiment of the present application, the BOG reliquefaction device 2 further comprises a liquid nitrogen inlet valve 18, a regulating valve 27 and a pressure sensor. The liquid nitrogen inlet valve 18 is arranged on the fifth pipeline 35 and is used for controlling the opening and closing of the fifth pipeline 35. The regulating valve 27 is arranged on the fifth pipeline 35 between the liquid nitrogen inlet valve 18 and the heat exchanger 19, and is used for controlling the flow of the liquid nitrogen in the fifth pipeline 35, thereby adjusting the efficiency of the heat exchanger 19 in liquefying BOG. The pressure sensor is arranged on the fifth pipeline 35 between the regulating valve 27 and the heat exchanger 19, is electrically connected with the regulating valve 27, and is used for detecting the internal pressure of the fifth pipeline 35.

[0059] In an embodiment of the present application, the BOG reliquefaction device 2 further comprises a gas-liquid separation tank inlet valve 23 arranged on the second pipeline 32. The gas-liquid separation tank inlet valve 23 is used for controlling the opening and closing of the second pipeline 32. When the gas-liquid separation tank inlet valve 23 is opened, the LNG in the heat exchanger 19 can flow into the gas-liquid separation tank 30 under the action of gravity.

[0060] In an embodiment of the present application, the BOG reliquefaction device 2 further comprises a temperature sensor arranged on the first pipeline 31 between the heat exchanger 19 and the vaporizer 21, and a pressure stabilizing tank outlet valve 20 arranged on the third pipeline 33 and electrically connected with the temperature sensor. The temperature sensor is used for detecting the temperature value of the nitrogen gas in the first pipeline 31, and controlling the opening degree of the pressure stabilizing tank outlet valve 20 according to the detected temperature value.

[0061] When the temperature of the nitrogen gas at the outlet of the heat exchanger 19 is relatively high, it indicates that the flow of the BOG in the third pipeline 33 is relatively large, and then the opening degree of the pressure stabilizing tank outlet valve 20 is controlled to be small, so that the flow of the BOG is reduced. When the temperature of the nitrogen gas at the outlet of the heat exchanger 19 is relatively low, it indicates that the flow of the BOG in the third pipeline 33 is relatively small, and then the opening degree of the pressure stabilizing tank outlet valve 20 is controlled to be large, so that the flow of the BOG is increased.

[0062] In one embodiment of the present application, the BOG reliquefaction device 2 further comprises a liquid level meter and a second booster valve 25. The liquid level meter is arranged in the gas-liquid separation tank 30 and is electrically connected with the liquid outlet valve 26. The liquid level meter is used to detect the liquid level of LNG in the gas-liquid separation tank 30. The second booster valve 25 is arranged at the inlet of the self-boosting heat exchanger 24. The self-boosting heat exchanger 24 is used to vaporize part of the liquid LNG in the gas-liquid separation tank 30 and send it back to the gas-liquid separation tank 30, so as to increase the internal pressure of the gas-liquid separation tank 30 and ensure that the gas-liquid separation tank 30 has a large pressure difference with the first tank truck 38, so that the LNG in the gas-liquid separation tank 30 flows into the first tank truck 38 under the action of pressure.

[0063] In one embodiment of the present application, the BOG reliquefaction device 2 further comprises a nitrogen exhaust valve 22. The nitrogen exhaust valve 22 is arranged on the first pipeline 31 away from the heat exchanger 19 on the side of the vaporizer 21. The nitrogen exhaust valve 22 is used to control the discharge of nitrogen.

[0064] In one embodiment of the present application, the BOG reliquefaction device 2 further comprises a flow meter 29. The flow meter 29 is arranged on the LNG filling main pipe and is used to detect the total flow of LNG delivered to the LNG power ship storage tank 4.

[0065] In one embodiment of the present application, the LNG ship filling device 6 comprises an LNG filling main pipe and at least one LNG ship filling assembly. One end of the LNG filling main pipe is in communication with the liquid inlet of the LNG power ship storage tank 4.

[0066] In the present embodiment, the LNG ship filling device 6 comprises three LNG ship filling assemblies. The three LNG ship filling assemblies are arranged side by side, so that the LNG power ship storage tank 4 can be filled with LNG by the three second tank trucks 5. Of course, the number of LNG ship filling assemblies is not limited to three, and can also be two, four or more, which is determined according to actual needs.

[0067] The LNG ship filling assembly comprises an LNG submersible pump 7, a submersible pump outlet valve 8, a booster vaporizer 11, a booster liquid phase valve 15, a booster gas phase valve 16, a check valve 17, a booster port 12, a gas phase port 13 and a liquid phase port 14. The LNG submersible pump 7 is used to pump the LNG in the second tank truck 5 into the LNG power ship storage tank 4. The liquid outlet of the LNG submersible pump 7 is in communication with the other end of the LNG filling main pipe through a branch. The submersible pump outlet valve 8 is arranged on the branch. By arranging the submersible pump outlet valve 8 on the branch, each LNG ship filling assembly can be controlled individually. When one of the LNG ship filling assemblies is temporarily suspended, the submersible pump outlet valve 8 corresponding to the LNG ship filling assembly is closed, which will not affect the normal work of other LNG ship filling assemblies.

[0068] The liquid inlet of the LNG submersible pump 7 is communicated with the liquid phase port 14 through a liquid inlet pipe 37, and the liquid phase port 14 is used to communicate with the liquid phase outlet of the second tank truck 5. A check valve 17 is arranged in the liquid inlet pipe 37, and the check valve 17 is used to prevent the LNG in the liquid inlet pipe 37 from flowing back into the second tank truck 5. The gas return port of the LNG submersible pump 7 is communicated with the gas phase port 13 through a gas return pipe 36, and the gas phase port 13 is used to communicate with the gas phase outlet of the second tank truck 5. A pressurized gas phase valve 16 is arranged in the gas return pipe 36, and the pressurized gas phase valve 16 is used to control the opening and closing of the gas return pipe 36. The pressurized port 12 is communicated with the inlet of the pressurized liquid phase valve 15, the outlet of the pressurized liquid phase valve 15 is communicated with the inlet of the pressurized gasifier 11, and the pressurized port 12 is used to communicate with the pressurized outlet of the second tank truck 5. The pressurized liquid phase valve 15 is used to control the opening and closing of the pressurized port 12.

[0069] The outlet of the pressurized gasifier 11 is communicated with the gas return pipe 36 between the pressurized gas phase valve 16 and the LNG submersible pump 7. The pressurized gasifier 11 is used to exchange heat between the LNG input by the second tank truck 5 and air, and to transport the generated BOG into the second tank truck 5 to increase the pressure in the second tank truck 5.

[0070] In an embodiment of the present application, the LNG ship filling device 6 further comprises a submersible pump gas phase valve 9 and a submersible pump inlet valve 10. The submersible pump gas phase valve 9 is arranged in the gas return pipe 36 between the pressurized gas phase valve 16 and the LNG submersible pump 7. The submersible pump inlet valve 10 is arranged in the liquid inlet pipe 37 between the LNG submersible pump 7 and the check valve 17.

[0071] The present application also provides an LNG ship filling method based on BOG reliquefaction, which is based on the LNG ship filling method based on BOG reliquefaction in any of the above embodiments. The filling method comprises:

[0072] In step S100, the LNG in the second tank truck 5 is transported into the pressurized gasifier 11 through the pressurized port 12 to exchange heat with air to generate BOG.

[0073] Since the pressure in the storage tank of the second tank truck 5 is usually only 1-2 bar, and the difference in liquid level between the second tank truck 5 and the liquid inlet of the LNG submersible pump 7 is low, it cannot meet the pressure and flow rate requirements of the LNG submersible pump 7, so the pressurized gasifier 11 is needed to pressurize the storage tank of the second tank truck 5. The LNG in the second tank truck 5 flows into the pressurized liquid phase valve 15 through the pressurized port 12 by gravity, and then flows into the pressurized gasifier 11, where it exchanges heat with air to form BOG.

[0074] In step S200, the generated BOG is transported into the second tank truck 5 through the gas phase port 13 to increase the pressure in the second tank truck 5.

[0075] The generated BOG enters the second tank car 5 through the pressurized gas phase valve 16 and the gas phase port 13 in sequence, and the pressure in the second tank car 5 is increased at this time.

[0076] In step S300, the LNG in the second tank car 5 is delivered to the LNG submersible pump 7 through the liquid phase port 14 under the driving of the pressure, and the LNG is pumped to the LNG powered ship storage tank 4 by the LNG submersible pump 7.

[0077] With the increase of the pressure in the second tank car 5, the LNG in the second tank car 5 flows into the LNG submersible pump 7 through the check valve 17 and the submersible pump inlet valve 10 under the action of the pressure, and the LNG enters the LNG filling main through the submersible pump outlet valve 8 under the pumping of the LNG submersible pump 7, is metered by the flow meter 29, and then enters the LNG powered ship storage tank 4, so as to realize the ship fuel filling. During the filling process, the gas return port of the LNG submersible pump 7 is communicated with the gas phase outlet of the second tank car 5 and the outlet of the pressurized vaporizer 11, so as to achieve the purpose of pressure equalization.

[0078] In step S400, the BOG in the LNG powered ship storage tank 4 enters the pressure stabilizing tank 28 and then enters the heat exchanger 19.

[0079] The BOG re-liquefaction is carried out at the same time as the LNG ship filling, the BOG in the LNG powered ship storage tank 4 enters the pressure stabilizing tank 28 for temporary storage, at this time, all the valves of the BOG re-liquefaction device 2 are in the closed state, the liquid nitrogen in the liquid nitrogen storage tank 1 is gasified by the booster 3 and returned to the liquid nitrogen storage tank 1, so as to increase the pressure in the liquid nitrogen storage tank 1, and when the liquid nitrogen storage tank 1 has sufficient pressure, the BOG re-liquefaction is started.

[0080] In step S500, the liquid nitrogen output by the liquid nitrogen storage device enters the heat exchanger 19 and exchanges heat with the BOG, so as to liquefy the BOG to obtain LNG.

[0081] When the liquid nitrogen storage tank 1 has sufficient pressure, the liquid nitrogen inlet valve 18, the regulating valve 27 and the pressure stabilizing tank outlet valve 20 are opened, the liquid nitrogen enters the heat exchanger 19 under the control of the regulating valve 27 to provide cold energy for the BOG liquefaction, the gasified nitrogen gas is discharged through the nitrogen gas exhaust valve 22 or used for pipeline purging after the temperature is increased to normal temperature in the vaporizer 21. The BOG input into the pressure stabilizing tank 28 is liquefied to obtain liquid LNG in the heat exchanger 19.

[0082] In step S600, the liquefied LNG enters the gas-liquid separation tank 30 and is delivered to the first tank car 38 after reaching a predetermined amount.

[0083] The liquid LNG enters the gas-liquid separation tank 30 through the inlet valve 23 of the gas-liquid separation tank under the action of gravity. When the liquid level in the gas-liquid separation tank 30 reaches a preset value, the liquid level meter controls the opening of the outlet valve 26, and the LNG is transported to the first tank truck 38 under the action of pressure difference.

[0084] In one embodiment of the present application, the filling method further comprises the following steps after the step of liquefying the obtained LNG into the gas-liquid separation tank 30 and transporting to the first tank truck 38 after reaching a predetermined amount:

[0085] The unliquefied BOG in the gas-liquid separation tank 30 is transported to the heat exchanger 19 for condensation.

[0086] The unliquefied BOG in the gas-liquid separation tank 30 is transported to the outlet of the pressure stabilizing tank 28 under the action of pressure, and then reenters the heat exchanger 19 through the pressure stabilizing tank outlet valve 20 for condensation, further improving the recovery efficiency of the BOG.

[0087] In one embodiment of the present application, the filling method further comprises the following steps after the step of liquefying the obtained LNG into the gas-liquid separation tank 30 and transporting to the first tank truck 38 after reaching a predetermined amount:

[0088] After the LNG in the first tank truck 38 reaches the filling rate, the first tank truck 38 is moved to the position of the second tank truck 5 to replace the second tank truck 5 and re-fill the LNG into the LNG power ship storage tank 4.

[0089] In one embodiment of the present application, the filling method further comprises the following steps before the step of transporting the LNG in the second tank truck 5 to the booster gasifier 11 through the booster inlet 12 to exchange heat with air to generate BOG:

[0090] Purging: After the pipeline is connected, nitrogen gas is purged to remove moisture and oxygen in the pipeline. The inerting operation is not completed until the oxygen content in the pipeline is less than 1%, otherwise the second inerting operation is performed again until the requirements are met. After the inerting operation, the pipeline connection part is pressurized to the rated pressure of the pipeline using nitrogen gas to test whether there is a leak in the pipeline. After the inerting operation meets the requirements, natural gas is used to purify the filling pipeline to remove nitrogen gas in the pipeline.

[0091] Pre-cooling: After purging, the pump and pipeline need to be pre-cooled, and the pre-cooling process and steps S100 to S600 are consistent, which will not be described here.

[0092] Compared with the prior art, the LNG ship filling method based on BOG reliquefaction provided by the application effectively reduces energy waste and realizes zero carbon emission. Assuming that the BOG is saturated low-temperature evaporation gas, the pressure is 0.2-0.4 MPa, the temperature is-120- -140 DEG C, the processing capacity is 380 Nm3 / h, and the total amount is 8 tons, the LNG liquefaction amount is 0.68 m 3 / h, and the total output is 20.4 m 3 ; according to the LNG price of 5000 yuan / ton, 46000 yuan can be saved, nitrogen emission is used instead of BOG emission, the national environmental protection requirements are met, and zero carbon emission in the filling process is realized.

[0093] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. An LNG ship bunkering system based on BOG reliquefaction, characterized in that, include: LNG-powered ship storage tank (4); LNG ship refueling device (6), the outlet of which is connected to the inlet of the LNG-powered ship storage tank (4); The BOG reliquefaction unit (2) includes a heat exchanger (19), a pressure stabilizing tank (28), a gas-liquid separator (30), a vaporizer (21), a self-pressurizing heat exchanger (24), and a liquid outlet valve (26). The outlet of the heat exchanger (19) is connected to the first end of the first pipeline (31). The vaporizer (21) is connected in series to the first pipeline (31). The liquid outlet of the heat exchanger (19) is connected to the liquid inlet of the gas-liquid separator (30) through a second pipeline (32). The outlet of the pressure stabilizing tank (28) is connected to the gas inlet of the heat exchanger (19) through a third pipeline (33). The inlet of the pressure stabilizing tank (28) is connected to the outlet of the LNG-powered ship storage tank (4); the outlet of the gas-liquid separator (30) is connected to the third pipeline (33), and the outlet of the gas-liquid separator (30) is connected to the inlet of the first tank truck (38) through the fourth pipeline (34); the outlet valve (26) is located on the fourth pipeline (34); the inlet of the self-pressurizing heat exchanger (24) is connected to the outlet of the gas-liquid separator (30), and the outlet of the self-pressurizing heat exchanger (24) is connected to the inlet of the gas-liquid separator (30); The liquid nitrogen storage device has its outlet connected to the inlet of the heat exchanger (19) via a fifth pipeline (35).

2. The LNG ship bunkering system based on BOG reliquefaction according to claim 1, characterized in that, The liquid nitrogen storage device includes: Liquid nitrogen storage tank (1), the first outlet of the liquid nitrogen storage tank (1) is connected to the inlet of the heat exchanger (19) through the fifth pipeline (35); The inlet of the booster (3) is connected to the second outlet of the liquid nitrogen storage tank (1), and the outlet of the booster (3) is connected to the inlet of the liquid nitrogen storage tank (1). The first pressure boosting valve (39) is located at the inlet of the pressure booster (3).

3. The LNG ship bunkering system based on BOG reliquefaction according to claim 1, characterized in that, The BOG reliquefaction unit (2) also includes: A liquid nitrogen inlet valve (18) is installed on the fifth pipeline (35); A regulating valve (27) is installed on the fifth pipeline (35) between the liquid nitrogen inlet valve (18) and the heat exchanger (19); A pressure sensor is installed on the fifth pipeline (35) between the regulating valve (27) and the heat exchanger (19) and is electrically connected to the regulating valve (27).

4. The LNG ship bunkering system based on BOG reliquefaction according to any one of claims 1 to 3, characterized in that, The BOG reliquefaction unit (2) also includes: The inlet valve (23) of the gas-liquid separator is installed on the second pipeline (32).

5. The LNG ship bunkering system based on BOG reliquefaction according to any one of claims 1 to 3, characterized in that, The BOG reliquefaction unit (2) also includes: A temperature sensor is installed on the first pipeline (31) between the heat exchanger (19) and the vaporizer (21); The pressure stabilizing tank outlet valve (20) is installed on the third pipeline (33) and is electrically connected to the temperature sensor.

6. The LNG ship bunkering system based on BOG reliquefaction according to any one of claims 1 to 3, characterized in that, The BOG reliquefaction unit (2) also includes: A level gauge is installed in the gas-liquid separator (30), and the level gauge is electrically connected to the liquid outlet valve (26); The second pressure boosting valve (25) is located at the inlet of the self-pressurizing heat exchanger (24).

7. The LNG ship bunkering system based on BOG reliquefaction according to any one of claims 1 to 3, characterized in that, The LNG ship refueling device (6) includes: LNG refueling manifold, one end of which is connected to the inlet of the LNG-powered ship storage tank (4); At least one LNG ship bunkering assembly, the LNG ship bunkering assembly including an LNG submersible pump (7), a submersible pump outlet valve (8), a booster vaporizer (11), a booster liquid phase valve (15), a booster gas phase valve (16), a check valve (17), a booster port (12), a gas phase port (13), and a liquid phase port (14), the outlet of the LNG submersible pump (7) is connected to the other end of the LNG bunkering main pipe through a branch, the submersible pump outlet valve (8) is located on the branch, and the inlet of the LNG submersible pump (7) is connected to the main pipe through an inlet pipe. The liquid phase port (14) is connected, and the check valve (17) is located in the liquid inlet pipe; the return gas port of the LNG submersible pump (7) is connected to the gas phase port (13) through the return gas pipe, and the booster gas phase valve (16) is located in the return gas pipe; the booster port (12) is connected to the inlet of the booster liquid phase valve (15), the outlet of the booster liquid phase valve (15) is connected to the inlet of the booster vaporizer (11), and the outlet of the booster vaporizer (11) is connected to the return gas pipe between the booster gas phase valve (16) and the LNG submersible pump (7).

8. The LNG ship bunkering system based on BOG reliquefaction according to claim 7, characterized in that, The LNG ship refueling device (6) also includes: The submersible pump gas phase valve (9) is located in the return gas pipe between the booster gas phase valve (16) and the LNG submersible pump (7); The inlet valve (10) of the submersible pump is located in the inlet pipe between the LNG submersible pump (7) and the check valve (17).

9. A method for bunkering LNG ships based on BOG reliquefaction, said bunkering method being based on the BOG reliquefaction-based LNG ship bunkering system of claim 7 or 8, characterized in that, include: The LNG in the second tanker (5) is transported to the booster vaporizer (11) through the booster port (12) to exchange heat with air and generate BOG; The generated BOG is transported to the second tank car (5) through the gas phase port (13) to increase the pressure inside the second tank car (5); Driven by pressure, the LNG in the second tanker (5) is transported to the LNG submersible pump (7) through the liquid phase port (14), and then the LNG is pumped to the LNG-powered ship storage tank (4) through the LNG submersible pump (7). The BOG in the LNG-powered ship storage tank (4) enters the pressure stabilizing tank (28) and then enters the heat exchanger (19); The liquid nitrogen output from the liquid nitrogen storage device enters the heat exchanger (19) to exchange heat with BOG, thereby liquefying BOG to obtain LNG; The liquefied LNG enters the gas-liquid separator (30) and is then transported to the first tank truck (38) after reaching a predetermined quantity.

10. The LNG ship bunkering method based on BOG reliquefaction according to claim 9, characterized in that, While performing the steps of liquefying the LNG and feeding it into the gas-liquid separator (30), and then transferring it to the first tank truck (38) after reaching a predetermined quantity, the refueling method also includes: Unliquefied BOG in the gas-liquid separator (30) is transported to the heat exchanger (19) for condensation.

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