BOG return gas treatment device and method and LNG receiving station

Abstract

The invention relates to the technical field of liquefied natural gas receiving stations, in particular to a BOG return gas treatment device and method and an LNG receiving station. The BOG return gas treatment device comprises a shipment return gas arm, a desuperheater, an LNG storage tank and a BOG compression assembly. The shipment air return arm is used for conveying BOG; the desuperheater is provided with a desuperheating inlet and a desuperheating outlet, the desuperheating inlet is communicated with the shipment air return arm, and the desuperheater is used for cooling BOG; the LNG storage tank is communicated with the temperature reduction outlet and is used for performing cryogenic liquid separation on BOG; the BOG compression assembly communicates with the LNG storage tank and is used for compressing BOG.

Description

Technical Field

[0001] The present invention relates to the technical field of liquefied natural gas receiving stations, and in particular to a BOG return gas processing device and method and an LNG receiving station. Background Art

[0002] LNG (Liquefied Natural Gas) is a widely used high-quality energy source with the characteristics of high calorific value, high efficiency, low pollution and strong environmental friendliness. With the in-depth promotion of ecological civilization construction, the development prospects of the LNG industry chain are broad, especially with the interconnection of LNG energy in coastal areas and inland rivers in my country, the demand for loading operations of coastal LNG receiving stations that are planned, constructed and in operation has become more prominent. A large amount of BOG (Boil Off Gas, flash steam) will be generated during LNG loading operations. These BOGs need to be pressurized by the fans on the LNG transport ship, returned to the LNG receiving station through the gas phase loading arm, and then pressurized by the BOG compressor. Finally, according to the production load and external transmission requirements of the LNG receiving station, the external transmission or re-condensation process is selected.

[0003] In the related art, BOG carries some liquid when entering the BOG compressor, causing the BOG compressor to run with liquid, increasing the failure and shutdown rate of the BOG compressor, and affecting the safety of the BOG system and LNG storage tanks of the entire plant. Summary of the invention

[0004] The present application provides a BOG return gas processing device, method and LNG receiving station, which to a certain extent solves the technical problem in the related art that BOG carries some liquid when entering the BOG compressor, causing the BOG compressor to run with liquid, increasing the failure and shutdown rate of the BOG compressor, and affecting the safety of the BOG system and LNG storage tanks of the entire plant.

[0005] In a first aspect, an embodiment of the present application provides a BOG return gas processing device, comprising:

[0006] Ship loading return air arm, used to transport BOG;

[0007] a desuperheater, having a desuperheating inlet and a desuperheating outlet, wherein the desuperheating inlet is connected to the ship loading return air arm, and the desuperheater is used to cool the BOG;

[0008] An LNG storage tank, connected to the temperature reduction outlet, and used for deep cooling and liquid separation of the BOG;

[0009] The BOG compression assembly is communicated with the LNG storage tank, and the BOG compression assembly is used to compress the BOG.

[0010] In some embodiments, under the condition that the LNG storage tank performs cryogenic separation on the BOG, the mass ratio of the LNG to the BOG in the LNG storage tank is 10:1 to 15:1.

[0011] In some embodiments, the desuperheater includes a main body, a spray head and an LNG low-pressure pump, the desuperheating inlet and the desuperheating outlet are both arranged on the main body, the spray head is arranged in the main body, the spray head is also connected to the LNG storage tank, and the LNG low-pressure pump is arranged on a pipeline connecting the spray head and the LNG storage tank to transport the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG.

[0012] In some embodiments, the device further includes a flow control valve and a flow meter, wherein the flow control valve and the flow meter are arranged on the pipeline between the spray head and the LNG low-pressure pump, the flow meter is used to detect the flow rate of the spraying LNG, and the flow control valve is used to control the flow rate of the spraying LNG so that the BOG maintains a gaseous state in the desuperheater.

[0013] In a second aspect, an embodiment of the present application provides a BOG return gas treatment method, the method is implemented according to the above-mentioned BOG return gas treatment device, and the method includes:

[0014] The BOG is transported from the ship loading return air arm to a desuperheater to cool the BOG;

[0015] The cooled BOG is transported to the LNG storage tank to perform deep cooling and liquid separation on the BOG;

[0016] The separated BOG is transported to the BOG compression assembly for compression.

[0017] In a second aspect, an embodiment of the present application provides a BOG return gas treatment method, the method is implemented according to the above-mentioned BOG return gas treatment device, and the method includes:

[0018] Turning on the LNG low-pressure pump to deliver the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG;

[0019] The cooled BOG is transported to the LNG storage tank to perform deep cooling and liquid separation on the BOG;

[0020] The separated BOG is transported to the BOG compression assembly for compression.

[0021] In some embodiments, the step of turning on the LNG low-pressure pump to deliver the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG includes:

[0022] The LNG low-pressure pump is turned on to transport the LNG in the LNG storage tank to the spray head to form spray LNG, and the flow rate of the spray LNG is controlled to keep the BOG in the desuperheater in a gas state.

[0023] In some embodiments, the steps after turning on the LNG low-pressure pump to deliver the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG include:

[0024] The temperature value of the BOG after cooling is detected. If the temperature value is greater than or equal to N, the flow rate of the spraying LNG is increased to continue cooling the BOG until the BOG meets the requirements.

[0025] In a fourth aspect, an embodiment of the present application provides an LNG receiving station, including an LNG transport ship and the above-mentioned BOG return gas processing device, wherein the ship loading return gas arm is arranged on the LNG transport ship.

[0026] In some embodiments, the LNG transport ship further comprises a liquid loading arm and a gas-liquid loading arm, both of which are connected to the LNG storage tank to transport the LNG in the LNG storage tank to the transport ship.

[0027] The beneficial effects of this application are as follows:

[0028] The present application provides a BOG return gas processing device, method and LNG receiving station. Since the BOG after being cooled by the desuperheater will be first transported to the LNG storage tank, a large amount of LNG with a relatively low temperature in the LNG storage tank can fully deep-cool the BOG to reach the saturation temperature of the mixed gas, thereby achieving the purpose of gas-liquid separation, avoiding the BOG compressor from running with liquid to a certain extent, reducing the failure and shutdown rate of the BOG compressor, and ensuring the technical problems of the safety of the BOG system and LNG storage tanks of the entire plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0030] Figure 1 A schematic diagram showing an LNG receiving station provided in an embodiment of the present application.

[0031] Description of reference numerals:

[0032] 1-LNG receiving station, 100-BOG return gas processing device, 110-shipping return gas arm, 120-desuperheater, 130-LNG storage tank, 140-BOG compression assembly, 141-BOG compressor inlet buffer tank, 142-BOG compressor, 150-flow control valve, 160-temperature sensor, 200-LNG transport ship, 210-shipping liquid phase arm, 220-shipping gas-liquid arm. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between various components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] During the LNG loading process, the LNG in the storage tank of the LNG receiving station is transported to the liquid phase loading arm of the terminal through a low-pressure pump, and then enters the LNG storage tank on the LNG transport ship through the liquid phase loading arm and the manifold. As the loading operation proceeds, the heat transfer effect of the LNG receiving station, the terminal loading pipeline and the external environment and the heat input of the low-pressure pump and the storage tank on the LNG transport ship will cause a large amount of BOG to be generated during the loading operation. These BOGs need to be pressurized by the fans on the LNG transport ship, returned to the LNG receiving station through the gas phase loading arm, and pressurized by the BOG compressor. According to the production load and external transmission requirements of the LNG receiving station, the external transmission or re-condensation process is selected.

[0038] In the related technology, the traditional LNG loading process in LNG receiving stations at home and abroad is as follows: Figure 1 As shown. The LNG in the LNG storage tank is transported to the dock loading and unloading arm through the loading main pipe by a low-pressure pump, and then enters the LNG tanker. The generated BOG is pressurized by the return fan on the LNG tanker, and then transported to the BOG main pipe in the receiving station through the gas phase return arm and the return gas main pipe. Due to factors such as the heat input of the loading facilities, the change of loading load, and environmental conditions, the flow rate, temperature, and load fluctuation range of the generated BOG are quite different and irregular. Therefore, the BOG flow rate and temperature entering the BOG compressor inlet buffer tank and the BOG compressor fluctuate greatly, which has a great impact on the determination of the BOG compressor design conditions, and even causes unreasonable selection of the BOG compressor, resulting in poor operability and stability of the BOG compressor. For this reason, a desuperheater is set at the inlet of the BOG compressor inlet buffer tank to reduce the temperature of the high-temperature BOG gas to a stable temperature (such as -110°C) to ensure that the gas operating parameters entering the BOG compressor are relatively stable. However, in the above implementation process, the following problems need to be solved in the loading return gas treatment process:

[0039] (1) Figure 1 As shown, the BOG gas returned from the ship enters the BOG main pipe through the return gas main pipe and is directly transported to the BOG compressor inlet liquid separator tank. The higher temperature BOG gas and the low-temperature liquid LNG from the LNG low-pressure output main pipe are mixed in the desuperheater, and the low-temperature liquid LNG is used to cool the BOG gas. The BOG gas with a higher temperature variation range (temperature is about -130℃~-20℃) will cause the injection amount of LNG in the BOG compressor inlet buffer tank to increase. The insufficient mixing effect of the desuperheater will cause the gas to carry small droplets into the BOG compressor inlet buffer tank, increasing the difficulty of controlling the liquid level of the BOG compressor inlet buffer tank and the smooth and efficient operation. If there is too much liquid LNG in the BOG compressor inlet buffer tank, or the gas carries small droplets into the compressor, it will cause the BOG compressor to stop due to failure, affecting the efficient, smooth and safe operation of the compressor.

[0040] (2) As mentioned above, when the liquid level of the buffer tank at the inlet of the BOG compressor rises, its liquid separation effect will be weakened to a certain extent. According to the years of operating experience of some domestic LNG receiving stations, the rise of the liquid level of the buffer tank at the inlet of the BOG compressor or the poor control effect will inevitably cause a part of the gas to carry a small amount of liquid into the BOG compressor, causing the BOG compressor to run with liquid, increasing the failure and shutdown rate of the BOG compressor, and affecting the safety of the BOG system and LNG storage tanks of the entire plant.

[0041] In order to improve the above technical problems to a certain extent, the embodiments of the present application provide a BOG return gas processing device, method and LNG receiving station, which reduce the situation of BOG compressor running with liquid, reduce the BOG compressor failure shutdown rate, and ensure the safety of the BOG system and LNG storage tanks of the entire plant.

[0042] The following is a description of the embodiments of the present application in conjunction with the accompanying drawings:

[0043] The embodiment of the present application provides a BOG return gas processing device 100, comprising a shipboard return gas arm 110, a desuperheater 120, an LNG storage tank 130 and a BOG compression assembly 140. The shipboard return gas arm 110 is used to transport BOG; the desuperheater 120 has a desuperheating inlet and a desuperheating outlet, the desuperheating inlet is connected to the shipboard return gas arm 110, and the desuperheater 120 is used to cool the BOG; the LNG storage tank 130 is connected to the desuperheating outlet, and the LNG storage tank 130 is used to perform deep cold liquid separation on the BOG; the BOG compression assembly 140 is connected to the LNG storage tank 130, and the BOG compression assembly 140 is used to compress the BOG.

[0044] The loading return air arm 110 is used to transport BOG generated during the LNG loading process. Due to factors such as heat input of loading facilities, loading load changes, and environmental conditions, the temperature fluctuation of BOG is relatively large. In order not to affect the efficacy of the subsequent BOG compression assembly 140, after being output by the loading return air arm 110, BOG first enters the desuperheater 120 for cooling. The cooling process may cause BOG to carry small droplets. If the BOG at this time directly enters the BOG compression assembly 140 for compression, the BOG compression assembly 140 will be operated with liquid, which will also affect the efficacy of the BOG compression assembly 140. Therefore, the BOG needs to be cryogenically separated through the LNG storage tank 130. The LNG storage tank 130 stores a large amount of low-temperature LNG, which can fully cryogenically cool the BOG to reach the saturation temperature of the mixed gas, thereby achieving the purpose of gas-liquid separation and improving the situation where BOG carries small droplets into the compressed BOG.

[0045] The BOG compression assembly 140 includes a BOG compressor 142 inlet buffer tank 141 and a BOG compressor 142 connected in sequence. The BOG compressor 142 inlet buffer tank 141 is used in various systems to buffer the pressure fluctuation of the system, so that the system works more smoothly, and the BOG compressor 142 is used to compress BOG. ​​Compared with the related art in which BOG directly enters the BOG compressor 142 inlet buffer tank with a relatively narrow space for gas-liquid separation after passing through the desuperheater 120, the embodiment of the present application makes full use of the huge gas phase space and the wide gas-liquid joint surface at the top of the LNG storage tank 130 to achieve a good gas-liquid separation effect, which can meet the gas-liquid separation index.

[0046] It should be noted that the volume of the LNG storage tank 130 can be 100,000 to 200,000 cubic meters, and the inherent LNG storage tank 130 of the LNG receiving station 1 can be directly used, thereby ensuring the BOG gas separation effect without adding new equipment, ensuring the economy of the receiving station construction investment and operation costs.

[0047] Of course, a new LNG storage tank 130 specifically used for deep-cold liquid separation of BOG may also be built, and there is no limitation to this.

[0048] In some embodiments, in order to ensure the cryogenic effect, under the condition that the LNG storage tank 130 performs cryogenic separation on the BOG, the mass ratio of LNG to BOG in the LNG storage tank 130 is 10:1 to 15:1.

[0049] The temperature of the cryogenic LNG in the LNG storage tank 130 is maintained at about -158°C. Through simulation and engineering operation experience, when the cooled BOG enters the LNG storage tank 130 for cryogenic liquid separation, when the mass ratio of liquid LNG to BOG gas is within the range of 10:1 to 15:1, the cryogenic LNG has the best cryogenic effect on BOG, which can ensure the liquid separation effect of BOG. ​​If the amount of BOG gas is too large, the flow rate of LNG liquid can be appropriately increased to separate and cryogenically liquefy the BOG gas.

[0050] In some embodiments, the cooler 120 includes a main body, a spray head and an LNG low-pressure pump. The cooling inlet and the cooling outlet are both arranged on the main body. The spray head is arranged in the main body. The spray head is also connected to the LNG storage tank 130. The LNG low-pressure pump is arranged on a pipeline connecting the spray head and the LNG storage tank 130 to transport the LNG in the LNG storage tank 130 to the spray head to form spray LNG to cool the BOG.

[0051] After BOG enters the main body from the cooling inlet, the LNG low-pressure pump is started to transport the low-temperature LNG in the LNG storage tank 130 to the spray head to form spray LNG to cool the BOG in the main body. The spraying action of the spray head forms a fine jet of LNG and fully mixes with the high-temperature BOG gas, which can achieve the effect of reducing the temperature of the BOG gas. At the same time, the cooled BOG may also carry droplets, so the cooled BOG needs to enter the LNG storage tank 130 for deep cooling and liquid separation.

[0052] In some embodiments, the device also includes a flow control valve 150 and a flow meter, which are arranged in the pipeline between the spray head and the LNG low-pressure pump. The flow meter is used to detect the flow rate of the spraying LNG, and the flow control valve 150 is used to control the flow rate of the spraying LNG so that the BOG remains in a gaseous state in the desuperheater 120.

[0053] In order to prevent BOG from losing too much heat and becoming liquid during the cooling process, the flow rate of the sprayed LNG needs to be controlled by the flow control valve 150 so that BOG can remain in a gaseous state during the cooling process. The flow meter can directly detect the flow value of the sprayed LNG, that is, the flow value of the sprayed LNG that meets the requirements can be preset, and the flow control valve 150 can be adjusted so that the reading displayed by the flow meter meets the preset value.

[0054] Specifically, when the mass ratio of liquid LNG to BOG gas is in the range of 1:12 to 1:15 (the ratio varies with the temperature of the BOG gas), the cooling effect is best, and the BOG can be kept in a gaseous state in the desuperheater 120. The flow value of the spraying LNG can be preset according to the ratio.

[0055] Based on the same inventive concept, the embodiment of the present application further provides a BOG return gas treatment method, which is implemented according to the above-mentioned BOG return gas treatment device 100, and the method includes:

[0056] S1: BOG is transported from the ship loading return air arm 110 to the desuperheater 120 to cool the BOG.

[0057] The loading return air arm 110 is used to transport BOG generated during the LNG loading process. Due to factors such as the heat input of the loading facilities, changes in the loading load, and environmental conditions, the temperature fluctuation of BOG is relatively large. In order not to affect the effectiveness of the subsequent BOG compression component 140, after being output through the loading return air arm 110, the BOG first enters the desuperheater 120 for cooling.

[0058] S2: transporting the cooled BOG to the LNG storage tank 130 to perform deep cooling and liquid separation on the BOG;

[0059] The cooling process may cause BOG to carry small droplets. If the BOG directly enters the BOG compression assembly 140 for compression, the BOG compression assembly 140 will be operated with liquid, which will also affect the efficiency of the BOG compression assembly 140. Therefore, the BOG needs to be cryogenically separated through the LNG storage tank 130. The LNG storage tank 130 stores a large amount of low-temperature LNG, which can fully cryogenically cool the BOG to reach the saturation temperature of the mixed gas, thereby achieving the purpose of gas-liquid separation and improving the situation where the BOG carries small droplets into the compressed BOG.

[0060] S3: The separated BOG is transported to the BOG compression assembly 140 for compression.

[0061] The BOG compression assembly 140 includes a BOG compressor 142 inlet buffer tank 141 and a BOG compressor 142 connected in sequence. The BOG compressor 142 inlet buffer tank 141 is used to buffer pressure fluctuations in various systems to make the system work more smoothly, and the BOG compressor 142 is used to compress BOG.

[0062] Based on the same inventive concept, the embodiment of the present application further provides a BOG return gas treatment method, which is implemented according to the above BOG return gas treatment device 100, and includes:

[0063] S4: Turn on the LNG low-pressure pump to deliver the LNG in the LNG storage tank 130 to the spray head to form spray LNG to cool the BOG.

[0064] After BOG enters the main body from the cooling inlet, the LNG low-pressure pump is started to transport the low-temperature LNG in the LNG storage tank 130 to the spray head to form spray LNG to cool the BOG in the main body. The spraying action of the spray head forms a fine jet of LNG and fully mixes with the high-temperature BOG gas, which can achieve the effect of reducing the temperature of the BOG gas. At the same time, the cooled BOG may also carry droplets, so the cooled BOG needs to enter the LNG storage tank 130 for deep cooling and liquid separation.

[0065] Specifically, the steps of turning on the LNG low-pressure pump to deliver the LNG in the LNG storage tank 130 to the spray head to form spray LNG to cool the BOG include:

[0066] S41 : Turn on the LNG low-pressure pump to deliver the LNG in the LNG storage tank 130 to the spray head to form spray LNG, and control the flow rate of the spray LNG to keep the BOG in the desuperheater 120 in a gas state.

[0067] In order to prevent BOG from losing too much heat and becoming liquid during the cooling process, the flow rate of the sprayed LNG needs to be controlled by the flow control valve 150 so that BOG can remain in a gaseous state during the cooling process. The flow meter can directly detect the flow value of the sprayed LNG, that is, the flow value of the sprayed LNG that meets the requirements can be preset, and the flow control valve 150 can be adjusted so that the reading displayed by the flow meter meets the preset value.

[0068] When the mass ratio of liquid LNG to BOG gas is in the range of 1:12 to 1:15, the cooling effect is the best, and BOG can be kept in a gaseous state in the desuperheater 120. The flow value of the spraying LNG can be preset according to the ratio.

[0069] S5: Detect the temperature value of the cooled BOG. ​​If the temperature value is greater than or equal to N, increase the flow rate of the sprayed LNG to continue cooling the BOG until the BOG meets the requirements.

[0070] When the intake air temperature of the BOG compressor 142 is high or fluctuates frequently, the operating conditions of the BOG compressor 142 will be diverse. The automatic adjustment of the BOG compressor 142 will be too frequent, triggering the temperature interlock and DCS control system inside the compressor. Under extreme conditions, the compressor will be shut down urgently. The unstable operation of the compressor will increase unnecessary operating costs, shorten the life of the compressor, and increase the operating and maintenance costs of the compressor.

[0071] Therefore, in order to ensure that the BOG entering the BOG compressor 142 meets the requirements, the temperature of the BOG needs to be detected after the BOG is cooled in the desuperheater 120. A temperature sensor 160 can be set on the pipeline between the desuperheating outlet and the LNG storage tank 130 to detect the temperature of the BOG. ​​If the temperature value is greater than or equal to N, the flow rate of the spraying LNG is increased to continue to cool the BOG until the BOG meets the requirements.

[0072] Specifically, the value of N may be -157°C.

[0073] S6: The cooled BOG is transported to the LNG storage tank 130 to perform deep cooling and liquid separation on the BOG.

[0074] The cooling process may cause BOG to carry small droplets. If the BOG directly enters the BOG compression assembly 140 for compression, the BOG compression assembly 140 will be operated with liquid, which will also affect the efficiency of the BOG compression assembly 140. Therefore, the BOG needs to be cryogenically separated through the LNG storage tank 130. The LNG storage tank 130 stores a large amount of low-temperature LNG, which can fully cryogenically cool the BOG to reach the saturation temperature of the mixed gas, thereby achieving the purpose of gas-liquid separation and improving the situation where the BOG carries small droplets into the compressed BOG.

[0075] S7: The separated BOG is transported to the BOG compression assembly 140 for compression.

[0076] The BOG compression assembly 140 includes a BOG compressor 142 inlet buffer tank 141 and a BOG compressor 142 connected in sequence. The BOG compressor 142 inlet buffer tank 141 is used to buffer pressure fluctuations in various systems to make the system work more smoothly, and the BOG compressor 142 is used to compress BOG.

[0077] Based on the same inventive concept, the embodiment of the present application further provides an LNG receiving station 1, including an LNG transport ship 200 and the above-mentioned BOG return gas processing device 100, and the loading return gas arm 110 is arranged on the LNG transport ship 200.

[0078] The beneficial effects of the LNG receiving station 1 are the same as those of the BOG return gas treatment device 100 described above, and will not be described in detail here.

[0079] In some embodiments, the LNG carrier 200 further comprises a loading liquid phase arm 210 and a loading gas-liquid arm 220, both of which are connected to the LNG storage tank 130 to transport the LNG in the LNG storage tank 130 to the carrier.

[0080] That is, the LNG storage tank 130 used for cryogenic liquid separation can directly use the inherent LNG storage tank 130 of the LNG receiving station 1, so that the liquid separation effect of BOG gas can be ensured without adding new equipment, and the economy of the construction investment and operation cost of the receiving station can be ensured. During the LNG loading operation, the LNG in the LNG storage tank 130 enters the storage tank of the LNG transport ship 200 through the loading liquid phase arm 210 and the loading gas-liquid arm 220, and the generated BOG is output by the loading gas return arm 110.

[0081] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A BOG return gas treatment device, characterized in that: include: Ship loading return air arm, used to transport BOG; a desuperheater, having a desuperheating inlet and a desuperheating outlet, wherein the desuperheating inlet is connected to the ship loading return air arm, and the desuperheater is used to cool the BOG; An LNG storage tank, connected to the temperature reduction outlet, and used for deep cooling and liquid separation of the BOG; The BOG compression assembly is communicated with the LNG storage tank, and the BOG compression assembly is used to compress the BOG.

2. The BOG return gas treatment device according to claim 1, characterized in that: Under the condition that the LNG storage tank performs cryogenic separation on the BOG, the mass ratio of the LNG to the BOG in the LNG storage tank is 10:1 to 15:

1.

3. The BOG return gas treatment device according to claim 1, characterized in that: The desuperheater includes a main body, a spray head and an LNG low-pressure pump. The desuperheating inlet and the desuperheating outlet are both arranged on the main body. The spray head is arranged in the main body, and the spray head is also connected to the LNG storage tank. The LNG low-pressure pump is arranged on a pipeline connecting the spray head and the LNG storage tank to transport the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG.

4. The BOG return gas treatment device according to claim 3, characterized in that: The device also includes a flow control valve and a flow meter, which are arranged on the pipeline between the spray head and the LNG low-pressure pump. The flow meter is used to detect the flow of the spraying LNG, and the flow control valve is used to control the flow of the spraying LNG so that the BOG remains in a gas state in the desuperheater.

5. A BOG return gas treatment method, characterized in that: The method is implemented by the BOG return gas treatment device according to any one of claims 1 to 4, and the method comprises: The BOG is transported from the ship loading return air arm to a desuperheater to cool the BOG; The cooled BOG is transported to the LNG storage tank to perform deep cooling and liquid separation on the BOG; The separated BOG is transported to the BOG compression assembly for compression.

6. A BOG return gas treatment method, characterized in that: The method is implemented by the BOG return gas treatment device according to claim 4, and the method comprises: Turning on the LNG low-pressure pump to deliver the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG; The cooled BOG is transported to the LNG storage tank to perform deep cooling and liquid separation on the BOG; The separated BOG is transported to the BOG compression assembly for compression.

7. The BOG return gas treatment method according to claim 6, characterized in that: The step of opening the LNG low-pressure pump to transport the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG includes: The LNG low-pressure pump is turned on to transport the LNG in the LNG storage tank to the spray head to form spray LNG, and the flow rate of the spray LNG is controlled to keep the BOG in the desuperheater in a gas state.

8. The BOG return gas treatment method according to claim 6, characterized in that: The steps after opening the LNG low-pressure pump to deliver the LNG in the LNG storage tank to the spray head to form spray LNG to cool the BOG include: The temperature value of the BOG after cooling is detected. If the temperature value is greater than or equal to N, the flow rate of the spraying LNG is increased to continue cooling the BOG until the BOG meets the requirements.

9. An LNG receiving station, characterized in that: It comprises an LNG transport ship and the BOG return gas processing device according to any one of claims 1 to 4, wherein the ship loading return gas arm is arranged on the LNG transport ship.

10. The LNG receiving station according to claim 9, characterized in that: The LNG transport ship also has a loading liquid phase arm and a loading gas-liquid arm, and both the loading liquid phase arm and the loading gas-liquid arm are connected to the LNG storage tank to transport the LNG in the LNG storage tank to the transport ship.

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