Method and apparatus for flash vapor control in liquefied natural gas receiving terminals

Abstract

This application discloses a method, apparatus, equipment, and machine-readable storage medium for flash vapor control in liquefied natural gas (LNG) receiving terminals, relating to the field of LNG equipment technology. The method includes: obtaining the internal pressure value of the LNG storage tank under zero or low export conditions; adjusting the compressor load of the flash vapor pipeline to reduce flash vapor in the tank when the internal pressure value exceeds a preset lower limit; and performing a pressure-holding operation on the cold-insulating circulation pipeline based on the internal pressure value to further reduce flash vapor in the LNG storage tank. By combining the reduction of the internal tank pressure with the pressure-holding operation of the cold-insulating circulation pipeline, this method can significantly reduce the generation and emission of flash vapor, thereby improving the overall efficiency of the flash vapor treatment process.

Description

Technical Field

[0001] This application relates to the field of liquefied natural gas equipment technology, and more specifically to a flash vapor control method, apparatus, equipment, and machine-readable storage medium for liquefied natural gas receiving stations. Background Technology

[0002] Liquefied Natural Gas (LNG), as a clean and efficient energy source, is widely used in my country's energy transition. However, during the operation of LNG receiving terminals, a large amount of Boil Off Gas (BOG) is inevitably generated. Currently, traditional BOG handling methods are unable to effectively handle BOG generated by equipment heat leakage and flash evaporation under special operating conditions, such as zero or low external output, leading to energy waste and increased environmental pressure.

[0003] To address the aforementioned issues, the industry has been seeking a flexible, efficient, and economical method for BOG management and optimization. Therefore, designing a simple-to-operate BOG management and optimization method suitable for specific operating conditions to improve BOG processing efficiency is a current technical problem that needs to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a flash steam management method, apparatus, equipment, and machine-readable storage medium for liquefied natural gas receiving terminals, in order to solve the problem of how to improve the efficiency of flash steam treatment in the prior art.

[0005] To achieve the above objectives, the first aspect of this application provides a flash vapor control method for a liquefied natural gas (LNG) receiving terminal, wherein the LNG receiving terminal includes an LNG storage tank, and a flash vapor pipeline and a cold storage circulation pipeline are respectively connected to the LNG storage tank; the method includes:

[0006] Obtain the internal pressure value of the liquefied natural gas storage tank under zero or low export conditions;

[0007] If the internal pressure is greater than the preset lower limit of the tank pressure, adjust the compressor load of the flash vapor pipeline to reduce the flash vapor in the tank.

[0008] Based on the internal pressure value, the pressure-holding operation of the cold circulation pipeline is used to reduce flash vapor in the liquefied natural gas storage tank.

[0009] In this embodiment of the application, adjusting the compressor load of the flash vapor pipeline to reduce flash vapor in the liquefied natural gas storage tank includes: obtaining the pressure change rate inside the storage tank; determining the adjustment amount of the compressor load based on the pressure change rate; and adjusting the compressor load based on the adjustment amount to reduce flash vapor in the liquefied natural gas storage tank.

[0010] In this embodiment of the application, adjusting the compressor load of the flash vapor pipeline to reduce flash vapor in the storage tank includes: obtaining a first pressure change rate inside the storage tank; determining an increase in the compressor load based on the first pressure change rate to reduce the internal pressure of the storage tank to the first pressure value; obtaining a second pressure change rate inside the storage tank when the internal pressure of the storage tank is the first pressure value; determining an adjustment amount of the compressor load based on the second pressure change rate to adjust the internal pressure of the storage tank to the second pressure value and reduce flash vapor in the liquefied natural gas storage tank; wherein the second pressure value is greater than or equal to a preset lower limit of the storage tank pressure value and less than or equal to the first pressure value.

[0011] In this embodiment of the application, determining the adjustment amount of the compressor load based on the second pressure change rate to adjust the internal pressure value of the storage tank to the second pressure value includes: determining the adjustment amount of the compressor load based on the second pressure change rate to adjust the pressure value of the storage tank to maintain the second pressure value.

[0012] In this embodiment of the application, determining the adjustment amount of the compressor load based on the second pressure change rate to adjust the internal pressure value of the storage tank to the second pressure value further includes: increasing the compressor load when the second pressure change rate is positive, so that the internal pressure change rate of the storage tank is negative; obtaining the second pressure value when the internal pressure change rate of the storage tank is negative; and reducing the compressor load when the second pressure value is less than or equal to the lower limit of the internal pressure value of the storage tank, so that the internal pressure change rate of the storage tank becomes zero.

[0013] In this embodiment of the application, the pressure-holding operation of the cold storage circulation pipeline to reduce flash vapor in the liquefied natural gas storage tank is based on the internal pressure value, including: when the internal pressure value is a second pressure value, the pressure-holding operation of the cold storage circulation pipeline to reduce flash vapor in the storage tank.

[0014] In this embodiment of the application, the second pressure value is equal to the preset lower limit of the tank pressure value, and the lower limit of the internal pressure value is 110 kPa.

[0015] A second aspect of this application provides a flash vapor control device for a liquefied natural gas receiving station, comprising: a memory configured to store instructions; and a processor configured to retrieve instructions from the memory and, when executing the instructions, to implement the flash vapor control method for a liquefied natural gas receiving station provided in any of the above embodiments.

[0016] A third aspect of this application provides a flash vapor control device for a liquefied natural gas (LNG) receiving station, comprising: the flash vapor control device for an LNG receiving station provided in the second aspect of this application; an LNG storage tank; a pressure sensor disposed within the LNG storage tank; a flash vapor treatment pipeline connected to the LNG storage tank; a compressor connected to the flash vapor treatment pipeline and used to compress the flash vapor in the flash vapor treatment pipeline; a cold insulation circulation pipeline connected to the LNG storage tank; a cold insulation circulation pipeline valve connected to the cold insulation circulation pipeline; and electrical connection devices for the compressor, pressure sensor, and cold insulation circulation pipeline valve, respectively.

[0017] A fourth aspect of this application provides a machine-readable storage medium storing instructions for causing a machine to perform the flash vapor control method for a liquefied natural gas receiving station provided in any of the preceding embodiments.

[0018] The above-mentioned technical solution, by combining the reduction of internal pressure in the storage tank with the pressure-holding operation of the cold insulation circulation pipeline, can significantly reduce the generation of flash steam and the possibility of flash steam emission, thereby improving the overall efficiency of the flash steam treatment process.

[0019] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0021] Figure 1 The illustration shows a schematic flowchart of a flash vapor control method for a liquefied natural gas receiving station according to an embodiment of this application;

[0022] Figure 2 Schematic illustration Figure 1 Step S104 is a flowchart according to an embodiment of this application;

[0023] Figure 3 Schematic illustration Figure 1 Step S104 is another flowchart according to an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0026] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0027] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0028] During the operation of liquefied natural gas (LNG) receiving terminals, flash vapor can be generated due to factors such as heat leakage from storage tanks, pipelines, and volume displacement. Based on the causes of flash vapor formation, the inventors of this application propose a flash vapor control method for LNG receiving terminals.

[0029] Figure 1 The illustration schematically shows a flow chart of a flash vapor control method for a liquefied natural gas receiving terminal according to an embodiment of this application. Figure 1As shown in the figure, this application provides a flash vapor control method for a liquefied natural gas (LNG) receiving terminal. The LNG receiving terminal includes an LNG storage tank, and a flash vapor pipeline and a cold storage circulation pipeline are respectively connected to the LNG storage tank. The method may include the following steps:

[0030] S102. Obtain the internal pressure value of the liquefied natural gas storage tank under zero or low external transmission conditions;

[0031] S104. When the internal pressure value is greater than the preset lower limit of the tank pressure value, adjust the compressor load of the flash steam pipeline to reduce the flash steam in the tank.

[0032] S106. Based on the internal pressure value, pressurize and maintain the cold circulation pipeline to reduce flash vapor in the liquefied natural gas storage tank.

[0033] The flash vapor pipeline method for liquefied natural gas (LNG) receiving terminals provided in this application reduces the flash vapor content in LNG storage tanks by adjusting the compressor load of the flash vapor pipeline according to the internal pressure of the natural gas storage tank under zero or low export conditions, in conjunction with the pressure-holding operation of the cold insulation circulation pipeline. Analysis shows that one reason for flash vapor generation at LNG receiving terminals is heat leakage in pipelines (unloading pipelines, cold insulation circulation pipelines, etc.). The cold insulation circulation pipeline itself is at a low temperature and can accommodate some flash vapor. Under zero or low export conditions, the pressure-holding operation treats the cold insulation circulation pipeline as a container, storing the flash vapor generated by heat leakage within the pipeline pressure limit, preventing it from returning to the LNG storage tank or entering the flash vapor pipeline, thereby reducing the amount of flash vapor that needs to be processed. By combining the reduction of the internal pressure of the storage tank with the pressure-holding operation of the cold insulation circulation pipeline, the generation and emission of flash vapor can be significantly reduced, thereby improving the overall efficiency of the flash vapor treatment process.

[0034] Understandably, liquefied natural gas (LNG) storage tanks are used to store LNG. Flash vapor generated in the LNG storage tanks can be transferred to a flash vapor pipeline and processed by a subsequent recondenser and / or booster compressor before being delivered to downstream users. Under zero-export conditions, the flash vapor, after being processed by the recondenser, can be returned to the storage tank. A cryogenic circulation pipeline draws LNG from the storage tanks, and the LNG drawn from the cryogenic circulation pipeline can be returned to the LNG storage tanks, for example, through the unloading manifold on the unloading side of the LNG receiving terminal. The cryogenic circulation pipeline is used to keep the unloading manifold cryogenic by circulating cryogenic LNG and to prepare for subsequent unloading operations. The compressor in the flash vapor pipeline is used to compress the volume of flash vapor drawn from the LNG storage tanks. Pressurization of the cryogenic circulation pipeline can be achieved by closing the cryogenic circulation pipeline valve.

[0035] In some embodiments of this application, step S104, adjusting the compressor load of the flash vapor pipeline to reduce flash vapor in the liquefied natural gas storage tank, may include:

[0036] Obtain the rate of pressure change inside the storage tank;

[0037] The adjustment amount of the compressor load is determined based on the rate of change of pressure;

[0038] Adjust the compressor load according to the adjustment amount to reduce flash vapor in the liquefied natural gas storage tank.

[0039] By obtaining the pressure change rate inside the storage tank, the amount of flash vapor change in the tank can be reflected. Therefore, the adjustment amount of the compressor load can be determined based on the pressure change rate, thereby reducing the flash vapor in the storage tank.

[0040] Understandably, the rate of change of pressure can be determined based on the change of pressure value over time. The adjustment of the compressor load can be an increase or a decrease.

[0041] Specifically, obtaining the rate of pressure change inside the storage tank can include:

[0042] Record the pressure values ​​at each preset time point within a preset time period;

[0043] Based on the pressure values ​​at each preset time point, determine the rate of pressure change inside the storage tank during the preset time period.

[0044] In some embodiments of this application, considering the relationship between the increase in flash vapor content in the storage tank and the compressor load, in order to achieve better flash vapor treatment effect, step S104, adjusting the compressor load of the flash vapor pipeline to reduce the flash vapor in the storage tank, may include:

[0045] S202, Obtain the first pressure change rate inside the storage tank;

[0046] S204. Based on the first pressure change rate, determine the increase in compressor load to reduce the internal pressure of the storage tank to the first pressure value.

[0047] S206. When the internal pressure of the storage tank is the first pressure value, obtain the second pressure change rate inside the storage tank.

[0048] S208. Based on the second pressure change rate, determine the adjustment amount of the compressor load to adjust the internal pressure value of the storage tank to the second pressure value and reduce the flash vapor in the liquefied natural gas storage tank; wherein the second pressure value is greater than or equal to the preset lower limit of the storage tank pressure value and less than or equal to the first pressure value.

[0049] When obtaining the first pressure change rate, the compressor load on the flash vapor pipeline has not yet changed. At this point, the first pressure change rate reflects the increase or decrease in the flash vapor content in the storage tank. Based on the first pressure change rate, the internal pressure of the storage tank is adjusted to the first pressure value, and then the second pressure change rate inside the storage tank is obtained. Because the compressor load increases, the second pressure change rate should be less than the first pressure change rate. Since the second pressure value is less than or equal to the first pressure value, the flash vapor content in the storage tank eventually decreases, or remains at the level when the internal pressure of the storage tank is the first pressure value. Accordingly, the second pressure change rate is less than or equal to zero.

[0050] Understandably, the sign of the first and second pressure change rates reflects the rate of increase or decrease of flash vapor in the storage tank. Due to heat leakage and other reasons, flash vapor is generated in the storage tank, resulting in a positive pressure change rate inside the tank, such as the first pressure change rate. Of course, the embodiments of this application are still applicable when the first pressure change rate is negative. After determining the increase in compressor load, the amount of flash vapor processed by the compressor increases, thereby reducing the first pressure change rate to the second pressure change rate. The second pressure change rate can be positive, negative, or zero. When the second pressure change rate is negative, it indicates that the flash vapor content in the storage tank is decreasing.

[0051] Specifically, in some embodiments of this application, step S208 may include:

[0052] Based on the second pressure change rate, the adjustment amount of the compressor load is determined to regulate the pressure value of the storage tank to maintain the second pressure value, thereby reducing flash vapor in the liquefied natural gas storage tank.

[0053] Maintaining the tank pressure at the second pressure value indicates that the flash vapor content in the tank remains at a constant level. Since flash vapor continues to be generated due to factors such as heat leakage from the tank, maintaining the tank pressure at the second pressure value represents a dynamic equilibrium.

[0054] Specifically, see Figure 3 In some other embodiments of this application, step S208 may include:

[0055] S302. When the second pressure change rate is positive, increase the load on the compressor so that the pressure change rate inside the tank is negative.

[0056] S304. Obtain the second pressure value when the rate of pressure change inside the storage tank is negative;

[0057] S306. If the second pressure value is less than or equal to the lower limit of the pressure value inside the storage tank, reduce the load on the compressor so that the pressure change rate inside the storage tank becomes zero.

[0058] In the above embodiment, in step S302, the second pressure change rate is positive, indicating that the internal pressure of the storage tank is still rising, reflecting that flash vapor is still increasing. Therefore, the compressor load is further increased until the pressure change rate inside the storage tank becomes negative, causing the pressure inside the storage tank to gradually decrease, thereby reducing the flash vapor content in the storage tank. During the process of the pressure inside the storage tank gradually decreasing, since there is an allowable minimum pressure value in the storage tank, when the pressure change rate inside the storage tank is negative, the second pressure value is monitored to see if it is less than the lower limit of the pressure value inside the storage tank. If the second pressure value is less than or equal to the lower limit of the pressure value inside the storage tank, the compressor load is reduced, which reduces the energy consumption of the compressor, keeps the pressure inside the storage tank at a reasonable level, and recovers and treats the flash vapor in the storage tank that caused the pressure rise.

[0059] Understandably, the lower limit of the pressure value can be, for example, a manually set lower limit value. The minimum allowable pressure of the storage tank can be, for example, 110 kPa. Then, the lower limit of the pressure value can be, for example, 120 kPa, 130 kPa, or other values ​​higher than 110 kPa. The setting of the lower limit of the pressure value can be adjusted according to the magnitude of the pressure change rate of the storage tank, so that in step S306, reducing the compressor load can timely adjust the pressure change rate inside the storage tank, keeping the second pressure value above the minimum allowable pressure of the storage tank.

[0060] In some embodiments of this application, step S106 includes:

[0061] When the internal pressure is at the second pressure value, the pressure-holding operation of the cold circulation pipeline is used to reduce flash vapor in the storage tank.

[0062] By increasing the compressor load to treat the flash vapor in the storage tank and reducing the pressure, there is still a risk of flash vapor emission when the internal pressure reaches the second pressure value. Therefore, pressure-holding operation in the cold insulation circulation pipeline is used to reduce the flash vapor in the storage tank. This further reduces flash vapor generation. Through comprehensive optimization, the operation process is simplified, flash vapor emission is effectively reduced, and flash vapor treatment efficiency is improved.

[0063] As stated above, in some embodiments of this application, the second pressure value is equal to the preset lower limit of the tank pressure value, and the lower limit of the internal pressure value is 110 kPa.

[0064] Even after increasing the compressor load to reduce the pressure in the storage tank to its lower limit, changes in external factors may still cause the flash vapor content in the tank to rise continuously. To prevent excessive compressor load, the flash vapor can be stored in the cold insulation circulation pipe through a pressure-holding operation, thus slowing down the increase in flash vapor content in the storage tank. When the compressor load decreases, or when the internal pressure of the cold insulation circulation pipe approaches or exceeds its upper pressure limit, the pressure-holding operation is stopped, allowing the flash vapor in the cold insulation circulation pipe to flow into the storage tank.

[0065] In summary, the flash steam management method for liquefied natural gas (LNG) receiving terminals provided in this application can improve flash steam processing efficiency. By combining optimization of tank depressurization operations and optimization of cold-insulated circulation pipeline pressure build-up operations, this method effectively improves flash steam processing efficiency under special operating conditions. The comprehensive optimization scheme of reducing tank pressure and optimizing short-stop operations of cold-insulated circulation pipelines can significantly reduce the generation and emission of flash steam, thereby improving the efficiency of the entire flash steam processing process. By adopting the above method, especially under zero or low export conditions, the generation and emission of flash steam can be reduced while ensuring the safe operation of the LNG receiving terminal. This helps reduce energy waste, greenhouse gas emissions, and achieve the goal of energy conservation and environmental protection. The flash steam management method for LNG receiving terminals provided in this application is simple and easy to operate. The steps of optimizing tank depressurization operations and optimizing short-stop operations of cold-insulated circulation pipelines are clear, and the method utilizes comprehensive control of existing equipment without the need for additional expensive equipment, thus improving its operability. The above method is applicable to various types of LNG receiving terminals, and performs particularly well under zero or low export conditions. Because of its simplicity and efficiency, this method is applicable to LNG receiving terminals of different sizes and types, providing a universal flash vapor treatment method for the LNG industry. Through an innovative combination of optimized tank depressurization operations and optimized short-stop operations in the cold-insulation circulation pipeline, this method offers a new approach to handling flash vapor under special operating conditions. The flexibility of this method allows for its application under various operating conditions, providing more options and technical means for flash vapor management in LNG receiving terminals.

[0066] This application also provides a flash vapor control device for a liquefied natural gas receiving station, including a memory and a processor.

[0067] The memory is configured to store instructions. The processor is configured to retrieve instructions from the memory and, when executing the instructions, to implement the flash vapor control method for a liquefied natural gas receiving station provided in any of the above embodiments.

[0068] This application also provides a flash vapor control device for a liquefied natural gas receiving station, including: the above-mentioned flash vapor control device for a liquefied natural gas receiving station, a liquefied natural gas storage tank, a pressure sensor, a flash vapor treatment pipeline, a compressor-connected flash vapor treatment pipeline, a cold insulation circulation pipeline, and a cold insulation circulation pipeline valve.

[0069] The pressure sensor is located inside the liquefied natural gas (LNG) storage tank. A flash vapor treatment pipeline connects to the LNG storage tank. A compressor is connected to the flash vapor treatment pipeline and is used to compress the flash vapor in the flash vapor treatment pipeline. A cold storage circulation pipeline connects to the LNG storage tank. A cold storage circulation pipeline valve is connected to the cold storage circulation pipeline. The compressor, pressure sensor, and cold storage circulation pipeline valve are electrically connected.

[0070] This application also provides a machine-readable storage medium storing instructions that cause a machine to execute the flash vapor control method for a liquefied natural gas receiving station provided in any of the above embodiments.

[0071] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0072] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0074] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0075] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0076] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0077] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0078] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0079] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for controlling flash vapor in a liquefied natural gas receiving terminal, characterized in that, The liquefied natural gas receiving terminal includes liquefied natural gas storage tanks, with flash vapor pipelines and cold storage circulation pipelines respectively connected to the liquefied natural gas storage tanks; the method includes: Under zero or low external transmission conditions, the internal pressure value of the liquefied natural gas storage tank is obtained; If the internal pressure value is greater than the preset lower limit of the tank pressure value, adjust the compressor load of the flash vapor pipeline to reduce the flash vapor in the tank; Based on the internal pressure value, the pressure-holding operation of the cold circulation pipeline is used to reduce flash vapor in the liquefied natural gas storage tank; The method of adjusting the compressor load on the flash vapor pipeline to reduce flash vapor in the storage tank includes: Obtain the first rate of pressure change inside the storage tank; Based on the first pressure change rate, the increase in the compressor load is determined to reduce the internal pressure of the storage tank to the first pressure value; When the internal pressure of the storage tank is the first pressure value, the second pressure change rate inside the storage tank is obtained; Based on the second pressure change rate, the adjustment amount of the compressor load is determined to adjust the internal pressure value of the storage tank to the second pressure value and reduce the flash vapor in the liquefied natural gas storage tank; wherein, the second pressure value is greater than or equal to the preset lower limit of the storage tank pressure value and less than or equal to the first pressure value; The step of pressurizing and maintaining the cold circulation pipeline according to the internal pressure value to reduce flash vapor in the liquefied natural gas storage tank includes: When the internal pressure is the second pressure value, the cold-insulating circulation pipeline is pressurized to reduce flash vapor in the storage tank.

2. The method according to claim 1, characterized in that, The step of determining the adjustment amount of the compressor load based on the second pressure change rate to adjust the internal pressure value of the storage tank to the second pressure value includes: Based on the second pressure change rate, the adjustment amount of the compressor load is determined to adjust the pressure value of the storage tank to maintain it at the second pressure value.

3. The method according to claim 1, characterized in that, Based on the second pressure change rate, the adjustment amount of the compressor load is determined to adjust the internal pressure of the storage tank to the second pressure value, and the method further includes: When the second pressure change rate is positive, the load on the compressor is increased so that the pressure change rate inside the storage tank is negative. When the rate of pressure change inside the storage tank is negative, the second pressure value is obtained; When the second pressure value is less than or equal to the lower limit of the pressure value inside the storage tank, the load of the compressor is reduced so that the pressure change rate inside the storage tank becomes zero.

4. The method according to claim 1, characterized in that, The second pressure value is equal to the preset lower limit of the tank pressure value, and the lower limit of the internal pressure value is 110 kPa.

5. A flash vapor control device for a liquefied natural gas receiving terminal, characterized in that, include: The memory is configured to store instructions; as well as The processor is configured to retrieve the instructions from the memory and, when executing the instructions, to implement the flash steam control method for a liquefied natural gas receiving station according to any one of claims 1 to 4.

6. A flash vapor control device for a liquefied natural gas receiving terminal, characterized in that, include: The apparatus according to claim 5; Liquefied natural gas storage tanks; A pressure sensor is installed inside the liquefied natural gas storage tank; A flash vapor treatment pipeline connects to the liquefied natural gas storage tank; The compressor is connected to the flash steam treatment pipeline and is used to compress the flash steam in the flash steam treatment pipeline; A cold-insulating circulation pipeline connects to the liquefied natural gas storage tank; A cold insulation circulation pipeline valve is connected to the cold insulation circulation pipeline; The compressor, the pressure sensor, and the cold-keeping circulation pipeline valve are electrically connected to the device.

7. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform the flash vapor control method for a liquefied natural gas receiving station according to any one of claims 1 to 4.

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