Control method and system for processing liquefied natural gas flow at LNG leading-in terminal

Abstract

The invention discloses a control method and system for processing liquefied natural gas flow at an LNG leading-in terminal, and relates to the technical field of liquefied natural gas, and the control method comprises the steps of obtaining LNG terminal information, obtaining LNG historical transmission data according to the LNG terminal information, obtaining a BOG temperature influence coefficient according to the LNG historical transmission data, and obtaining BOG compression power parameter information according to the LNG terminal information. According to the method, the generation conditions of the BOG at different temperatures in the LNG storage structure of the LNG terminal are accurately analyzed through the BOG temperature influence coefficient, a basis is provided for follow-up LNG transmission control, the LNG control efficiency is improved, LNG transmission is controlled through LNG transmission speed information, the stability and reliability of LNG transmission are ensured, and the method is suitable for popularization and application. And overpressure or decompression caused by too high or too low transmission speed is avoided, the BOG compression power is ensured to be adjusted in time while the BOG compression power adjusting frequency is reduced through the BOG compression power adjusting period, and the stability of LNG is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of liquefied natural gas, and specifically relates to a control method and system for processing a liquefied natural gas stream at an LNG import terminal. Background Art

[0002] Due to the accelerating development of the world economy, the global demand for energy has increased rapidly. Natural gas, with its excellent properties such as high efficiency, high quality, and cleanness, as well as its wide range of uses, has become a safe and clean energy source that is generally favored by countries around the world. Liquefied natural gas (LNG) is a high-quality clean energy source that is widely used in important fields such as industry and civil use, effectively replacing coal and petroleum, and becoming one of the most high-quality new energy sources in the 21st century. This is clearly reflected in the logistics industry and the passenger flow industry, and a large number of LNG fuel filling stations have been completed and put into use. After natural gas is pre-treated and liquefied, its volume is reduced to one-six-hundredth of its original volume, which greatly facilitates transportation.

[0003] Currently, for the control of the liquefied natural gas stream at the LNG import terminal, there are still problems such as being unable to accurately analyze the LNG historical transmission data, unable to accurately control the LNG transmission speed through the LNG historical transmission data, often directly transmitting LNG at a fixed rate, or only adjusting the LNG transmission speed based on environmental temperature, etc., unable to ensure the stability and reliability of LNG transmission, unable to accurately evaluate the BOG generated during the LNG transmission process, unable to timely adjust the BOG compression power and the LNG transmission speed, reducing the LNG transmission efficiency, and affecting the safety of LNG transmission. Summary of the Invention

[0004] To solve the above technical problems, a control method and system for processing a liquefied natural gas stream at an LNG import terminal are provided. This technical solution solves the problems mentioned in the above background art, such as being unable to accurately analyze the LNG historical transmission data, unable to accurately control the LNG transmission speed through the LNG historical transmission data, often directly transmitting LNG at a fixed rate, or only adjusting the LNG transmission speed based on environmental temperature, etc., unable to ensure the stability and reliability of LNG transmission, unable to accurately evaluate the BOG generated during the LNG transmission process, unable to timely adjust the BOG compression power and the LNG transmission speed, reducing the LNG transmission efficiency, and affecting the safety of LNG transmission.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A control method for processing a liquefied natural gas stream at an LNG import terminal, comprising:

[0007] Obtain LNG terminal information, where the LNG terminal information includes LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure. The LNG terminal structure includes an LNG storage structure and a BOG compression structure;

[0008] Obtain LNG historical transmission data according to the LNG terminal information;

[0009] Obtain the BOG temperature influence coefficient according to the LNG historical transmission data;

[0010] Obtain BOG compression power parameter information according to the LNG terminal information. The BOG compression power parameter information includes BOG compression power adjustment range information and BOG compression standard power information;

[0011] Obtain ambient temperature information;

[0012] Based on the ambient temperature information, obtain LNG transmission speed information based on the BOG temperature influence coefficient and the BOG compression power parameter information;

[0013] Import liquefied natural gas into the LNG terminal according to the LNG transmission speed information;

[0014] Obtain the BOG compression power standard adjustment value based on the BOG compression power adjustment requirement;

[0015] Obtain the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value;

[0016] Adjust the BOG compression power and the LNG transmission speed based on the BOG compression power adjustment period.

[0017] Preferably, the obtaining of the BOG temperature influence coefficient according to the LNG historical transmission data specifically includes:

[0018] Obtain historical ambient temperature information, BOG historical generation rate information corresponding to the historical ambient temperature, and LNG liquid level height information according to the LNG historical transmission data;

[0019] Obtain the maximum storage height information of the LNG storage structure based on the LNG terminal information;

[0020] Take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient;

[0021] Take the ratio of the BOG historical generation rate and the liquid level correction coefficient as the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient;

[0022] Obtain the LNG boiling point temperature information;

[0023] Take the ratio of the BOG historical correction generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient;

[0024] Group the LNG historical transmission data to obtain an LNG temperature influence data group, where the LNG temperature influence data group includes historical ambient temperature information and the ambient temperature influence coefficient corresponding to the historical ambient temperature;

[0025] Based on the LNG temperature influence data group, screen the ambient temperature influence coefficient based on the historical ambient temperature to obtain the ambient temperature influence reference coefficient;

[0026] Take the mean value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient.

[0027] Preferably, the grouping of the LNG historical transmission data to obtain the LNG temperature influence data group specifically includes:

[0028] Correspondingly match the BOG historical correction generation rate and the ambient temperature influence coefficient corresponding to each historical ambient temperature, and take the product of the BOG historical correction generation rate and the ambient temperature influence coefficient as the temperature rate coefficient corresponding to the historical ambient temperature;

[0029] Take the difference between the temperature rate coefficients corresponding to any two historical ambient temperatures as the temperature difference identification coefficient between the two historical ambient temperatures;

[0030] Take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value;

[0031] Based on the historical ambient temperature information and the LNG boiling point temperature information, take the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature;

[0032] Based on the historical characteristic ambient temperature, take the temperature difference reference value as the historical ambient temperature change threshold, and group the LNG historical transmission data to obtain the LNG temperature influence data group;

[0033] Among them, the difference between the maximum value and the minimum value of the historical ambient temperature in each LNG temperature influence data group is not greater than the temperature difference reference value.

[0034] Preferably, the screening of the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data group to obtain the ambient temperature influence reference coefficient specifically includes:

[0035] S100: Based on the LNG temperature influence data set, take the mean of the environmental temperature influence coefficients corresponding to each group of historical environmental temperatures as the data set temperature influence coefficient corresponding to this LNG temperature influence data set;

[0036] S200: Take half of the difference between the maximum data set temperature influence coefficient and the minimum data set temperature influence coefficient as the data set temperature influence coefficient difference threshold;

[0037] S300: Based on the data set temperature influence coefficient and the data set temperature influence coefficient difference threshold, obtain the environmental temperature influence coefficient threshold corresponding to each group of LNG temperature influence data sets;

[0038] S400: Screen the data in the LNG temperature influence data set with the environmental temperature influence coefficient threshold. If the environmental temperature influence coefficient corresponding to the historical environmental temperature in the LNG temperature influence data set exceeds the environmental temperature influence coefficient threshold, remove this historical environmental temperature and the corresponding environmental temperature influence coefficient;

[0039] S500: Repeat steps S100 - S400 until there is no data to be removed in each group of LNG temperature influence data sets, and obtain the LNG temperature influence reference data set;

[0040] S600: Take the environmental temperature influence coefficients corresponding to the historical environmental temperatures in all LNG temperature influence reference data sets as the environmental temperature influence reference coefficients.

[0041] Preferably, based on the environmental temperature information, based on the BOG temperature influence coefficient and the BOG compression power parameter information, obtaining the LNG transmission speed information specifically includes:

[0042] According to the LNG historical transmission data, obtain the corresponding BOG compression power data;

[0043] Based on the BOG temperature influence coefficient, obtain the BOG historical generation characteristic rate corresponding to each historical environmental temperature in the LNG historical transmission data;

[0044] Based on the LNG transmission batches in the LNG historical transmission data, divide the LNG historical transmission data in the same LNG transmission process into the same data set to obtain the LNG historical transmission data set;

[0045] For each LNG historical transmission data set, take the historical environmental temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical environmental temperature as the ordinate to establish a coordinate system, and obtain the BOG temperature influence evaluation difference curve;

[0046] The difference curve of the BOG temperature influence evaluation is fitted with a linear equation, and the one with the smallest slope is taken as the LNG historical transmission feature data set;

[0047] Based on the BOG compression power data and the BOG historical generation rate information in the LNG historical transmission feature data set, a BOG historical generation function is established with time as a variable;

[0048] According to the LNG historical transmission data, the historical pressure data of the storage structure is obtained, and the historical pressure data of the storage structure represents the internal pressure value of the storage structure during the LNG historical transmission process;

[0049] Based on the BOG historical generation function and the historical pressure data of the storage structure, the BOG compression conversion coefficient is obtained;

[0050] Obtain the current LNG liquid level height information;

[0051] According to the BOG compression conversion coefficient and the current LNG liquid level height information, the LNG transmission speed information is obtained;

[0052] Among them, the LNG transmission speed is specifically:

[0053]

[0054] In the formula, σ is the LNG transmission speed, S is the cross-sectional area of the LNG storage structure, R0 is the BOG compression standard power, k is the BOG compression conversion coefficient, h max is the maximum liquid level height of the LNG storage structure, T is the ambient temperature, T ref is the boiling point temperature of LNG, ω is the BOG temperature influence coefficient, h0 is the current LNG liquid level height, t1 and t2 are the start time and end time of LNG transmission corresponding to the LNG historical transmission feature data set, R(t) represents the BOG compression power at time t, W(t) represents the BOG historical generation rate at time t, P(t) represents the internal pressure value of the storage structure at time t, P0 represents the initial internal pressure value of the storage structure, V max represents the maximum volume inside the storage structure, and h(t) represents the LNG liquid level height at time t.

[0055] Preferably, the obtaining of the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value specifically includes:

[0056] Obtain the LNG storage structure wall temperature information corresponding to the current LNG liquid level height;

[0057] Based on the LNG transmission speed, obtain the LNG liquid level height time variation function;

[0058] Based on the LNG transmission speed, take the temperature of the LNG storage structure wall as the ambient temperature, take the function of the LNG liquid level height changing with time as the current LNG liquid level height, substitute it into the LNG transmission speed calculation formula, and obtain the function of the BOG target compression power changing with time;

[0059] According to the function of the BOG target compression power changing with time, with time as a variable until the difference between the BOG target compression power and the BOG compression standard power exceeds the BOG compression power standard adjustment value, obtain the BOG compression power difference characteristic time;

[0060] According to the BOG compression power difference characteristic time, obtain the BOG compression power adjustment period.

[0061] Furthermore, a control system for processing the liquefied natural gas flow at the LNG import terminal is proposed to implement the control method as described above, including:

[0062] A main control module, which is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the smallest slope as the LNG historical transmission characteristic data set, based on the BOG compression power data and the BOG historical generation rate information in the LNG historical transmission characteristic data set, with time as a variable, establish a BOG historical generation function, according to the LNG historical transmission data, obtain the historical pressure data of the storage structure, based on the BOG historical generation function and the historical pressure data of the storage structure, obtain the BOG compression conversion coefficient, according to the BOG compression conversion coefficient, obtain the LNG transmission speed information, for each LNG historical transmission data set, take the historical ambient temperature as the abscissa, and take the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, establish a coordinate system, obtain the BOG temperature influence evaluation difference curve, according to the LNG transmission speed information and the BOG compression power standard adjustment value, obtain the BOG compression power adjustment period, and based on the BOG compression power adjustment period, adjust the BOG compression power and the LNG transmission speed;

[0063] An information acquisition module, which is used to acquire LNG terminal information, LNG terminal structure information, and the structural parameter information corresponding to each LNG terminal structure, based on the LNG terminal information, acquire the maximum storage height information of the LNG storage structure, acquire the LNG boiling point temperature information, according to the LNG terminal information, acquire the LNG historical transmission data, and according to the LNG historical transmission data, acquire the historical ambient temperature information, the BOG historical generation rate information corresponding to the historical ambient temperature, and the LNG liquid level height information;

[0064] An evaluation module, which is used to use the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient, obtain the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient, use the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient, screen the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data group, obtain the ambient temperature influence reference coefficient, use the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient, correspond and match the BOG historical corrected generation rate and the ambient temperature influence coefficient corresponding to each historical ambient temperature, use the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value, and group the LNG historical transmission data based on the historical ambient temperature information and the LNG boiling point temperature information, and obtain the LNG temperature influence data group;

[0065] A display module, which interacts with the main control module and is used to output and display LNG terminal information, BOG temperature influence coefficient, ambient temperature information, LNG transmission speed information, and BOG compression power adjustment period.

[0066] Optionally, the main control module specifically includes:

[0067] A control unit, which is used to establish a coordinate system for each LNG historical transmission data set, with the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, obtain the BOG temperature influence evaluation difference curve, obtain the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value, and adjust the BOG compression power and the LNG transmission speed based on the BOG compression power adjustment period;

[0068] An information receiving unit, which interacts with the information acquisition module and the evaluation module and is used to receive data and transmit it to the data processing unit;

[0069] A data processing unit, which is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the minimum slope as the LNG historical transmission feature data set, establish a BOG historical generation function with time as a variable according to the BOG compression power data and BOG historical generation rate information in the LNG historical transmission feature data set, obtain the historical pressure data of the storage structure according to the LNG historical transmission data, obtain the BOG compression conversion coefficient based on the BOG historical generation function and the historical pressure data of the storage structure, and obtain the LNG transmission speed information according to the BOG compression conversion coefficient.

[0070] Optionally, the information acquisition module specifically includes:

[0071] A first acquisition unit, which is used to acquire LNG terminal information, LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure, acquire the maximum storage height information of the LNG storage structure based on the LNG terminal information, and acquire the LNG boiling point temperature information;

[0072] A second acquisition unit, which is used to acquire LNG historical transmission data according to the LNG terminal information, and acquire historical ambient temperature information, BOG historical generation rate information corresponding to the historical ambient temperature and LNG liquid level height information according to the LNG historical transmission data.

[0073] Optionally, the evaluation module specifically includes:

[0074] A first evaluation unit, which is used to take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient, obtain the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient, screen the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data group, obtain the ambient temperature influence reference coefficient, and take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient;

[0075] A second evaluation unit, which is used to correspond and match the BOG historical corrected generation rate and the ambient temperature influence coefficient corresponding to each historical ambient temperature, take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value, take the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature according to the historical ambient temperature information and the LNG boiling point temperature information, group the LNG historical transmission data based on the historical characteristic ambient temperature with the temperature difference reference value as the historical ambient temperature change threshold, and obtain the LNG temperature influence data group.

[0076] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0077] The present invention provides a control method and system for processing liquefied natural gas flow at an LNG import terminal. By using the BOG temperature influence coefficient, the generation status of BOG at different temperatures in the LNG storage structure of the LNG terminal is accurately analyzed, providing a basis for subsequent LNG transmission control, improving the LNG control efficiency. The LNG transmission is controlled based on the LNG transmission speed information, ensuring the stability and reliability of LNG transmission, and avoiding overpressure or underpressure caused by too fast or too slow transmission speed. By adjusting the BOG compression power regulation cycle, while reducing the BOG compression power regulation frequency, it ensures timely adjustment of the BOG compression power, ensuring the stability of LNG. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 is a flowchart of a control method for processing liquefied natural gas flow at an LNG import terminal proposed by the present invention;

[0079] Figure 2 is a flowchart for obtaining the BOG temperature influence coefficient in the present invention;

[0080] Figure 3 is a flowchart for obtaining LNG transmission speed information in the present invention;

[0081] Figure 4 is a flowchart for obtaining the BOG compression power regulation cycle in the present invention;

[0082] Figure 5 is a block diagram of the control system for processing liquefied natural gas flow at an LNG import terminal proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0083] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations.

[0084] Referring to Figure 1 - Figure 4 As shown, a control method for processing liquefied natural gas flow at an LNG import terminal in an embodiment of the present invention includes:

[0085] Obtaining LNG terminal information, where the LNG terminal information includes LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure, and the LNG terminal structure includes an LNG storage structure and a BOG compression structure;

[0086] According to the LNG terminal information, obtaining LNG historical transmission data;

[0087] Obtain the BOG temperature influence coefficient according to the historical LNG transfer data;

[0088] Specifically, obtaining the BOG temperature influence coefficient according to the historical LNG transfer data specifically includes:

[0089] Obtain the historical ambient temperature information, the BOG historical generation rate information corresponding to the historical ambient temperature, and the LNG liquid level height information according to the historical LNG transfer data;

[0090] Obtain the maximum storage height information of the LNG storage structure based on the LNG terminal information;

[0091] Take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient;

[0092] According to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical generation rate to the liquid level correction coefficient as the BOG historical corrected generation rate;

[0093] Obtain the LNG boiling point temperature information;

[0094] Take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient;

[0095] Group the historical LNG transfer data to obtain the LNG temperature influence data group, and the LNG temperature influence data group includes the historical ambient temperature information and the ambient temperature influence coefficient corresponding to the historical ambient temperature;

[0096] According to the LNG temperature influence data group, screen the ambient temperature influence coefficient based on the historical ambient temperature to obtain the ambient temperature influence reference coefficient;

[0097] Take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient.

[0098] In this solution, by introducing a liquid level correction coefficient and incorporating the ratio of the LNG liquid level height to the maximum storage height into the calculation, the influence of the liquid level change in the storage container on the BOG (boil-off gas) generation rate is effectively reflected. It can be understood that regardless of the liquid level, the fundamental driving force for LNG evaporation is the heat transfer from the environment. By monitoring the liquid level and temperature, the essence is to calculate the heat transfer area and temperature difference of the tank wall, so as to adjust the unloading speed or the BOG treatment load. In a vertical storage tank, the side area of the liquid in contact with the tank wall increases with the increase of the liquid level, resulting in more environmental heat being transferred into the liquid. Therefore, the BOG generation rate also increases with the increase of the liquid level. The LNG storage liquid level directly affects the gas-liquid two-phase equilibrium state. The higher the liquid level, the smaller the gas phase space, and the influence mechanism of the environmental temperature on BOG generation will change. The introduction of this correction coefficient avoids the defect of ignoring the actual capacity state of the storage structure in the traditional method, makes the calculation of the BOG generation rate more in line with the actual working conditions of terminal storage, improves the accuracy of data preprocessing, and establishes a quantitative correlation between the temperature variable and the BOG generation rate by combining the temperature difference between the LNG boiling point temperature and the environmental temperature to calculate the environmental temperature influence coefficient. BOG generation is essentially a temperature-driven phase change process. As a key parameter of the physical properties of LNG, the difference between the boiling point temperature and the environmental temperature directly determines the heat conduction intensity. By correlating the BOG historical corrected generation rate with this temperature difference, the influence law of environmental temperature fluctuations on the evaporation rate can be accurately captured, providing a more reliable thermodynamic basis for subsequent control strategies.

[0099] It should be noted that by grouping and screening the environmental temperature influence reference coefficient from the data, the interference of abnormal data is effectively filtered, and the adaptability and robustness of the model are enhanced. During the LNG transmission process, historical data may contain noises such as equipment start-stop and short-term fluctuations. By grouping and screening the reference coefficient and taking the average value, the long-term stable temperature influence characteristics can be extracted, avoiding the accidental errors of single data points, making the finally obtained BOG temperature influence coefficient more representative, suitable for general control under different seasons and climate conditions, improving the safety and economy of LNG terminal operation, and providing a reliable technical support for the efficient storage and transmission of liquefied natural gas.

[0100] Specifically, the LNG historical transmission data is grouped to obtain the LNG temperature influence data group, which specifically includes:

[0101] Match the BOG historical corrected generation rate corresponding to each historical environmental temperature with the environmental temperature influence coefficient, and use the product of the BOG historical corrected generation rate and the environmental temperature influence coefficient as the temperature rate coefficient corresponding to the historical environmental temperature;

[0102] Use the difference between the temperature rate coefficients corresponding to any two historical environmental temperatures as the temperature difference identification coefficient between the two historical environmental temperatures;

[0103] Take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference recognition coefficient as the temperature difference reference value;

[0104] According to the historical ambient temperature information and the LNG boiling point temperature information, take the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature;

[0105] Based on the historical characteristic ambient temperature, take the temperature difference reference value as the historical ambient temperature change threshold, group the LNG historical transmission data, and obtain the LNG temperature influence data group;

[0106] Among them, the difference between the maximum and minimum historical ambient temperatures in each LNG temperature influence data group is not greater than the temperature difference reference value.

[0107] In this solution, by multiplying the BOG historical correction generation rate by the ambient temperature influence coefficient to obtain the temperature rate coefficient, a quantitative correlation model between temperature change and BOG generation rate is established. This product factor not only reflects the direct driving effect of ambient temperature on BOG generation, but also integrates the influence of the actual working conditions after liquid level correction (such as the indirect effect of storage liquid level on gas-liquid equilibrium), making the coupling relationship between temperature and rate more in line with the actual operation scenario of the LNG terminal. Further, by screening the temperature difference reference value corresponding to the minimum difference through the temperature difference recognition coefficient, the stable interval of the influence of ambient temperature on BOG generation can be accurately located, excluding the interference of abnormal fluctuation data, and ensuring the reliability of the subsequent grouped data. For example, near the LNG boiling point temperature (about -162 °C), a small temperature change may significantly affect the phase change rate, and the sensitive interval can be locked through the minimum difference reference value, avoiding control misjudgment caused by temperature fluctuation noise.

[0108] It should be noted that when grouping the LNG historical transmission data, sort the data in ascending order of the difference between the historical ambient temperature and the LNG boiling point temperature. Starting from the first data, use the temperature difference reference value as the data grouping threshold for data grouping. For example, for the LNG historical transmission data A, B, C, D, where the historical ambient temperatures corresponding to the LNG historical transmission data A, B, C, D are a, b, c, d, if |a - c| ≤ L and |a - d| > L, then divide the LNG historical transmission data A, B, C into the same LNG temperature influence data group, and continue grouping with the LNG historical transmission data D as the starting data until all data grouping is completed. Each sub-item in the LNG temperature influence data group includes the historical ambient temperature and the ambient temperature influence coefficient corresponding to the historical ambient temperature.

[0109] Specifically, according to the LNG temperature influence data group, screen the ambient temperature influence coefficient based on the historical ambient temperature to obtain the ambient temperature influence reference coefficient, specifically including:

[0110] S100: Based on the LNG temperature influence data set, take the mean value of the environmental temperature influence coefficients corresponding to each group of historical environmental temperatures as the data set temperature influence coefficient corresponding to this LNG temperature influence data set;

[0111] S200: Take half of the difference between the maximum data set temperature influence coefficient and the minimum data set temperature influence coefficient as the data set temperature influence coefficient difference threshold;

[0112] S300: Based on the data set temperature influence coefficient and the data set temperature influence coefficient difference threshold, obtain the environmental temperature influence coefficient threshold corresponding to each group of LNG temperature influence data sets;

[0113] S400: Screen the data in the LNG temperature influence data set with the environmental temperature influence coefficient threshold. If the environmental temperature influence coefficient corresponding to the historical environmental temperature in the LNG temperature influence data set exceeds the environmental temperature influence coefficient threshold, then remove this historical environmental temperature and the corresponding environmental temperature influence coefficient;

[0114] S500: Repeat steps S100 - S400 until there is no data to be removed in each group of LNG temperature influence data sets, and obtain the LNG temperature influence reference data set;

[0115] S600: Take the environmental temperature influence coefficients corresponding to the historical environmental temperatures in all LNG temperature influence reference data sets as the environmental temperature influence reference coefficients.

[0116] In this solution, through the calculation of the mean value of the data set temperature influence coefficient (S100), the accidental fluctuations of single data points are effectively smoothed, making the temperature influence characteristics of each group of data more representative. For example, during the LNG transmission process, the influence coefficient corresponding to individual environmental temperatures may be abnormal due to short-term disturbances of equipment. Through the mean value processing, such noises can be weakened, highlighting the long-term stable temperature-evaporation rate correlation characteristics. Further, through the difference threshold screening (S200 - S400), the data deviating from the within-group mean by more than half of the range is regarded as an outlier and removed, avoiding the interference of extreme working conditions or measurement errors on the reference coefficient, ensuring that the finally retained environmental temperature influence reference coefficient can truly reflect the temperature sensitivity characteristics of the LNG terminal under normal working conditions. Through iterative screening (S500), the data in each LNG temperature influence reference data set satisfies the stable state of "no outlier can be removed", forming a refined reference coefficient set adapted to different temperature ranges.

[0117] It can be understood that for the data set temperature influence coefficient difference threshold, if the data set temperature influence coefficient corresponding to the LNG temperature influence data set is Z, the maximum data set temperature influence coefficient and the minimum data set temperature influence coefficient are Z max and Zmin , the difference threshold of the data group temperature influence coefficient:

[0118]

[0119] According to the LNG terminal information, obtain the BOG compression power parameter information, where the BOG compression power parameter information includes the BOG compression power adjustment range information and the BOG compression standard power information;

[0120] Obtain the ambient temperature information;

[0121] Based on the ambient temperature information, and based on the BOG temperature influence coefficient and the BOG compression power parameter information, obtain the LNG transmission speed information;

[0122] Specifically, based on the ambient temperature information, and based on the BOG temperature influence coefficient and the BOG compression power parameter information, obtaining the LNG transmission speed information specifically includes:

[0123] According to the LNG historical transmission data, obtain the corresponding BOG compression power data;

[0124] Based on the BOG temperature influence coefficient, obtain the BOG historical generation characteristic rate corresponding to each historical ambient temperature in the LNG historical transmission data;

[0125] Based on the LNG transmission batches in the LNG historical transmission data, divide the LNG historical transmission data in the same LNG transmission process into the same data set to obtain the LNG historical transmission data set;

[0126] For each LNG historical transmission data set, use the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate to establish a coordinate system and obtain the BOG temperature influence evaluation difference curve;

[0127] Use a linear equation to fit the BOG temperature influence evaluation difference curve, and take the one with the smallest slope as the LNG historical transmission characteristic data set;

[0128] According to the BOG compression power data and the BOG historical generation rate information in the LNG historical transmission characteristic data set, establish a BOG historical generation function with time as the variable;

[0129] According to the LNG historical transmission data, obtain the storage structure historical pressure data, where the storage structure historical pressure data represents the internal pressure value of the storage structure during the LNG historical transmission process;

[0130] Based on the BOG historical generation function and the storage structure historical pressure data, obtain the BOG compression conversion coefficient;

[0131] Obtain the current LNG liquid level height information;

[0132] According to the BOG compression conversion coefficient and the current LNG liquid level height information, obtain the LNG transmission speed information;

[0133] Among them, the specific LNG transmission speed is:

[0134]

[0135] In the formula, σ is the LNG transmission speed, S is the cross-sectional area of the LNG storage structure, R0 is the BOG compression standard power, k is the BOG compression conversion coefficient, h max is the maximum liquid level height of the LNG storage structure, T is the ambient temperature, T ref is the boiling point temperature of LNG, ω is the BOG temperature influence coefficient, h0 is the current LNG liquid level height, t1 and t2 are the LNG transmission start time and end time corresponding to the LNG historical transmission characteristic data set, R(t) represents the BOG compression power at time t, W(t) represents the BOG historical generation rate at time t, P(t) represents the internal pressure value of the storage structure at time t, P0 represents the initial internal pressure value of the storage structure, V max represents the maximum volume inside the storage structure, and h(t) represents the LNG liquid level height at time t.

[0136] In this solution, by dividing the LNG historical transmission data set and fitting the difference curve, the characteristic data set with the smallest slope (i.e., the working condition interval with the most stable temperature influence) is selected, effectively eliminating the interference of abnormal fluctuation data. For example, during the LNG transmission process, accidental equipment vibration or short-term sudden ambient temperature changes may cause abnormal BOG generation rate. By linearly fitting and screening the curve with the smallest slope, the long-term stable temperature-generation rate relationship can be focused on, making the subsequent established BOG historical generation function closer to the actual thermodynamic law, avoiding prediction deviations caused by data noise, providing a reliable mathematical model for precise control. Based on the BOG historical generation function and the historical pressure data of the storage structure, the BOG compression conversion coefficient is obtained, and according to the BOG compression conversion coefficient, the LNG transmission speed information is obtained, ensuring the stability and reliability of LNG transmission.

[0137] According to the LNG transmission speed information, import the liquefied natural gas into the LNG terminal;

[0138] Based on the BOG compression power adjustment requirement, obtain the BOG compression power standard adjustment value;

[0139] According to the LNG transmission speed information and the BOG compression power standard adjustment value, obtain the BOG compression power adjustment period;

[0140] Specifically, according to the LNG transmission speed information and the BOG compression power standard adjustment value, obtain the BOG compression power adjustment period, which specifically includes:

[0141] Obtain the LNG storage structure wall temperature information corresponding to the current LNG liquid level height;

[0142] Based on the LNG transmission speed, obtain the LNG liquid level height time variation function;

[0143] According to the LNG transmission speed, take the LNG storage structure wall temperature as the ambient temperature, and take the LNG liquid level height time variation function as the current LNG liquid level height, and substitute them into the LNG transmission speed calculation formula to obtain the BOG target compression power time variation function;

[0144] According to the BOG target compression power time variation function, with time as a variable until the difference between the BOG target compression power and the BOG compression standard power exceeds the BOG compression power standard adjustment value, obtain the BOG compression power difference characteristic time;

[0145] According to the BOG compression power difference characteristic time, obtain the BOG compression power adjustment period.

[0146] In this solution, by obtaining the LNG storage structure wall temperature as the ambient temperature in real time and incorporating it into the calculation of the BOG target compression power, the model is made closer to the actual thermodynamic environment at the terminal. The wall temperature directly affects the heat exchange rate between LNG and the outside world and is a key driving factor for BOG generation. Compared with the traditional fixed ambient temperature assumption, this step achieves accurate capture of the temperature boundary conditions. Combining the liquid level height time variation function and dynamically substituting it into the transmission speed formula, the constructed BOG target compression power time variation function can reflect the impact of the liquid level dynamic change on the compression demand in real time (such as when the liquid level drops, the gas phase space increases, and the compression power needs to be adjusted to maintain pressure balance), avoiding the control lag or over-regulation caused by the static model due to working condition changes. By solving the difference characteristic time between the BOG target compression power and the standard power, the system can automatically identify the time critical points of "need to adjust" and "stable operation". For example, when the difference between the target compression power and the standard power exceeds the preset adjustment value (such as due to a sudden increase in the BOG generation rate caused by a sudden rise in the ambient temperature), the system triggers the adjustment period, avoiding the frequent start-stop or adjustment delay that may be caused by the traditional fixed-period adjustment (such as timing adjustment). This dynamic threshold determination based on real-time data makes the working cycle of the compression system accurately match the actual BOG generation / processing demand, reduces the ineffective operation time of the equipment, and extends the hardware life.

[0147] It should be noted that the LNG liquid level height time variation function is:

[0148]

[0149] Take the temperature of the LNG storage structure wall as the ambient temperature, take the function of the LNG liquid level height changing with time as the current LNG liquid level height, substitute the LNG transmission speed into the LNG transmission speed calculation formula, and obtain the function of the BOG target compression power changing with time:

[0150]

[0151] In the formula, time t is the independent variable, and the BOG target compression power R is the dependent variable, T h is the temperature of the LNG storage structure wall;

[0152] Increase the time t until the difference between the BOG target compression power and the BOG compression standard power exceeds the BOG compression power standard adjustment value, obtain the BOG compression power difference characteristic time, and use the BOG compression power difference characteristic time as the BOG compression power adjustment period.

[0153] Based on the BOG compression power adjustment period, adjust the BOG compression power and the LNG transmission speed.

[0154] Refer to Figure 5 As shown, further, in combination with the above control method for processing the liquefied natural gas flow at the LNG import terminal, a control system for processing the liquefied natural gas flow at the LNG import terminal is proposed, including:

[0155] The main control module, which is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the smallest slope as the LNG historical transmission feature data set, establish a BOG historical generation function with time as the variable according to the BOG compression power data and the BOG historical generation rate information in the LNG historical transmission feature data set, obtain the historical pressure data of the storage structure according to the LNG historical transmission data, obtain the BOG compression conversion coefficient based on the BOG historical generation function and the historical pressure data of the storage structure, obtain the LNG transmission speed information according to the BOG compression conversion coefficient, for each LNG historical transmission data set, establish a coordinate system with the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, obtain the BOG temperature influence evaluation difference curve, obtain the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value, and adjust the BOG compression power and the LNG transmission speed based on the BOG compression power adjustment period;

[0156] An information acquisition module, which is used to acquire LNG terminal information, LNG terminal structure information, and structure parameter information corresponding to each LNG terminal structure. Based on the LNG terminal information, it acquires the maximum storage height information of the LNG storage structure, acquires the boiling point temperature information of LNG, acquires the LNG historical transmission data according to the LNG terminal information, and acquires the historical ambient temperature information, the BOG historical generation rate information corresponding to the historical ambient temperature, and the LNG liquid level height information according to the LNG historical transmission data;

[0157] An evaluation module, which is used to take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient, acquire the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient, screen the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data group, acquire the ambient temperature influence reference coefficient, take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient, match the BOG historical corrected generation rate corresponding to each historical ambient temperature with the ambient temperature influence coefficient, take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value, and group the LNG historical transmission data based on the historical ambient temperature information and the LNG boiling point temperature information to acquire the LNG temperature influence data group;

[0158] A display module, which interacts with the main control module and is used to output and display the LNG terminal information, the BOG temperature influence coefficient, the ambient temperature information, the LNG transmission speed information, and the BOG compression power adjustment period.

[0159] The main control module specifically includes:

[0160] A control unit, which is used to establish a coordinate system for each LNG historical transmission data set, with the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, acquire the BOG temperature influence evaluation difference curve, acquire the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value, and adjust the BOG compression power and the LNG transmission speed based on the BOG compression power adjustment period;

[0161] An information receiving unit, which interacts with the information acquisition module and the evaluation module and is used to receive data and transmit it to the data processing unit;

[0162] A data processing unit, which is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the smallest slope as the LNG historical transmission feature data set, establish a BOG historical generation function with time as a variable according to the BOG compression power data and BOG historical generation rate information in the LNG historical transmission feature data set, obtain the storage structure historical pressure data according to the LNG historical transmission data, obtain the BOG compression conversion coefficient based on the BOG historical generation function and the storage structure historical pressure data, and obtain the LNG transmission speed information according to the BOG compression conversion coefficient.

[0163] An information acquisition module, specifically including:

[0164] A first acquisition unit, which is used to acquire LNG terminal information, LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure, acquire the maximum storage height information of the LNG storage structure based on the LNG terminal information, and acquire the LNG boiling point temperature information;

[0165] A second acquisition unit, which is used to acquire LNG historical transmission data according to the LNG terminal information, and acquire historical ambient temperature information, BOG historical generation rate information corresponding to the historical ambient temperature and LNG liquid level height information according to the LNG historical transmission data.

[0166] An evaluation module, specifically including:

[0167] A first evaluation unit, which is used to take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient, obtain the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient, screen the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data set, obtain the ambient temperature influence reference coefficient, and take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient;

[0168] The second evaluation unit is used to match the BOG historical correction generation rate corresponding to each historical ambient temperature with the ambient temperature influence coefficient, take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value, and based on the historical ambient temperature information and the LNG boiling point temperature information, take the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature. Based on the historical characteristic ambient temperature, take the temperature difference reference value as the historical ambient temperature change threshold to group the LNG historical transmission data and obtain the LNG temperature influence data group.

[0169] In summary, the advantages of the present invention are as follows: By using the LNG historical transmission data, the BOG temperature influence coefficient is obtained. Through the BOG temperature influence coefficient, the generation status of BOG at different temperatures in the LNG storage structure of the LNG terminal is accurately analyzed, providing a basis for subsequent LNG transmission control and improving the LNG control efficiency. Based on the ambient temperature information, the LNG transmission speed information is obtained based on the BOG temperature influence coefficient and the BOG compression power parameter information. The LNG transmission is controlled through the LNG transmission speed information, ensuring the stability and reliability of the LNG transmission and avoiding overpressure or underpressure caused by too fast or too slow transmission speed. Through the LNG transmission speed information and the BOG compression power standard adjustment value, the BOG compression power adjustment period is obtained. By means of the BOG compression power adjustment period, while reducing the BOG compression power adjustment frequency, it ensures timely adjustment of the BOG compression power, ensuring the stability of the LNG.

[0170] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A control method for processing a liquefied natural gas stream at an LNG import terminal, characterized in that, Including: Obtain LNG terminal information, where the LNG terminal information includes LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure. The LNG terminal structure includes an LNG storage structure and a BOG compression structure; Obtain LNG historical transmission data according to the LNG terminal information; Obtain the BOG temperature influence coefficient according to the LNG historical transmission data; Obtain BOG compression power parameter information according to the LNG terminal information. The BOG compression power parameter information includes BOG compression power adjustment range information and BOG compression standard power information; Obtain ambient temperature information; Based on the ambient temperature information, obtain LNG transmission speed information based on the BOG temperature influence coefficient and the BOG compression power parameter information; Import liquefied natural gas into the LNG terminal according to the LNG transmission speed information; Obtain the BOG compression power standard adjustment value based on the BOG compression power adjustment requirement; Obtain the BOG compression power adjustment period according to the LNG transmission speed information and the BOG compression power standard adjustment value; Adjust the BOG compression power and the LNG transmission speed based on the BOG compression power adjustment period.

2. The control method for processing a liquefied natural gas stream at an LNG import terminal according to claim 1, wherein, The step of obtaining the BOG temperature influence coefficient according to the LNG historical transmission data specifically includes: Obtain historical ambient temperature information, BOG historical generation rate information corresponding to the historical ambient temperature, and LNG liquid level height information according to the LNG historical transmission data; Obtain the maximum storage height information of the LNG storage structure based on the LNG terminal information; Take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient; According to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical generation rate to the liquid level correction coefficient as the BOG historical corrected generation rate; Obtain the LNG boiling point temperature information; Take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient; Group the LNG historical transmission data to obtain an LNG temperature influence data group, where the LNG temperature influence data group includes historical ambient temperature information and the ambient temperature influence coefficient corresponding to the historical ambient temperature; According to the LNG temperature influence data group, screen the ambient temperature influence coefficient based on the historical ambient temperature to obtain the ambient temperature influence reference coefficient; Take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient.

3. A control method for processing a liquefied natural gas stream at an LNG import terminal according to claim 2, characterized in that, The step of grouping the LNG historical transmission data to obtain the LNG temperature influence data group specifically includes: Correspondingly match the BOG historical corrected generation rate and the ambient temperature influence coefficient corresponding to each historical ambient temperature, and take the product of the BOG historical corrected generation rate and the ambient temperature influence coefficient as the temperature rate coefficient corresponding to the historical ambient temperature; Take the difference between the temperature rate coefficients corresponding to any two historical ambient temperatures as the temperature difference identification coefficient between the two historical ambient temperatures; Take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value; According to the historical ambient temperature information and the LNG boiling point temperature information, the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information is taken as the historical characteristic ambient temperature; Based on the historical characteristic ambient temperature, using the temperature difference reference value as the historical ambient temperature change threshold, group the LNG historical transmission data to obtain the LNG temperature influence data groups; Among them, the difference between the maximum and minimum historical ambient temperatures in each LNG temperature influence data group is not greater than the temperature difference reference value.

4. A control method for processing a liquefied natural gas stream at an LNG import terminal according to claim 2, characterized in that, According to the LNG temperature influence data groups, screening the ambient temperature influence coefficients based on the historical ambient temperature to obtain the ambient temperature influence reference coefficient, specifically including: S100: According to the LNG temperature influence data groups, take the mean value of the ambient temperature influence coefficients corresponding to the historical ambient temperatures of each group as the data group temperature influence coefficient corresponding to the LNG temperature influence data group; S200: Take half of the difference between the maximum data group temperature influence coefficient and the minimum data group temperature influence coefficient as the data group temperature influence coefficient difference threshold; S300: According to the data group temperature influence coefficient and the data group temperature influence coefficient difference threshold, obtain the ambient temperature influence coefficient threshold corresponding to each LNG temperature influence data group; S400: Screen the data in the LNG temperature influence data groups with the ambient temperature influence coefficient threshold. If the ambient temperature influence coefficient corresponding to the historical ambient temperature in the LNG temperature influence data group exceeds the ambient temperature influence coefficient threshold, then remove the historical ambient temperature and the corresponding ambient temperature influence coefficient; S500: Repeat steps S100 - S400 until there is no data to remove in each LNG temperature influence data group, and obtain the LNG temperature influence reference data groups; S600: Take the ambient temperature influence coefficients corresponding to the historical ambient temperatures in all LNG temperature influence reference data groups as the ambient temperature influence reference coefficient.

5. A control method for processing a liquefied natural gas stream at an LNG import terminal according to claim 1, characterized in that, Based on the ambient temperature information, based on the BOG temperature influence coefficient and the BOG compression power parameter information, obtain the LNG transmission speed information, specifically including: According to the LNG historical transmission data, obtain the corresponding BOG compression power data; Based on the BOG temperature influence coefficient, obtain the BOG historical generation characteristic rate corresponding to each historical ambient temperature in the LNG historical transmission data; Based on the LNG transmission batches in the LNG historical transmission data, divide the LNG historical transmission data in the same LNG transmission process into the same data set to obtain the LNG historical transmission data set; For each LNG historical transmission data set, taking the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, establish a coordinate system to obtain the BOG temperature influence evaluation difference curve; Fit the BOG temperature influence evaluation difference curve with a linear equation, and take the one with the minimum slope as the LNG historical transmission characteristic data set; According to the BOG compression power data and the BOG historical generation rate information in the LNG historical transmission characteristic data set, establish a BOG historical generation function with time as the variable; Based on the historical LNG transfer data, obtain the historical pressure data of the storage structure, where the historical pressure data of the storage structure represents the internal pressure value of the storage structure during the historical LNG transfer; Based on the BOG historical generation function and the historical pressure data of the storage structure, obtain the BOG compression conversion coefficient; Obtain the current LNG liquid level height information; Based on the BOG compression conversion coefficient and the current LNG liquid level height information, obtain the LNG transfer speed information; Among them, the LNG transfer speed is specifically: Where, σ is the LNG transfer speed, S is the cross-sectional area of the LNG storage structure, R0 is the BOG compression standard power, k is the BOG compression conversion coefficient, h max is the maximum liquid level height of the LNG storage structure, T is the ambient temperature, T ref is the boiling point temperature of LNG, ω is the BOG temperature influence coefficient, h0 is the current LNG liquid level height, t1 and t2 are the start time and end time of LNG transfer corresponding to the LNG historical transfer characteristic data set, R(t) represents the BOG compression power at time t, W(t) represents the BOG historical generation rate at time t, P(t) represents the internal pressure value of the storage structure at time t, P0 represents the initial internal pressure value of the storage structure, V max represents the maximum volume inside the storage structure, and h(t) represents the LNG liquid level height at time t.

6. A control method for processing a liquefied natural gas stream at an LNG import terminal according to claim 1, characterized in that, The obtaining of the BOG compression power adjustment period according to the LNG transfer speed information and the BOG compression power standard adjustment value specifically includes: Obtain the LNG storage structure wall temperature information corresponding to the current LNG liquid level height; Based on the LNG transfer speed, obtain the LNG liquid level height time variation function; According to the LNG transfer speed, take the LNG storage structure wall temperature as the ambient temperature, and take the LNG liquid level height time variation function as the current LNG liquid level height, substitute them into the LNG transfer speed calculation formula, and obtain the BOG target compression power time variation function; According to the BOG target compression power time variation function, with time as the variable until the difference between the BOG target compression power and the BOG compression standard power exceeds the BOG compression power standard adjustment value, obtain the BOG compression power difference characteristic time; According to the BOG compression power difference characteristic time, obtain the BOG compression power adjustment period.

7. A control system for processing a liquefied natural gas stream at an LNG import terminal, for implementing the control method according to any one of claims 1-6, characterized in that, Including: The main control module is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the smallest slope as the LNG historical transfer characteristic data set, establish a BOG historical generation function with time as the variable according to the BOG compression power data and the BOG historical generation rate information in the LNG historical transfer characteristic data set, obtain the historical pressure data of the storage structure according to the LNG historical transfer data, obtain the BOG compression conversion coefficient based on the BOG historical generation function and the historical pressure data of the storage structure, obtain the LNG transfer speed information according to the BOG compression conversion coefficient, for each LNG historical transfer data set, establish a coordinate system with the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, obtain the BOG temperature influence evaluation difference curve, obtain the BOG compression power adjustment period according to the LNG transfer speed information and the BOG compression power standard adjustment value, and adjust the BOG compression power and the LNG transfer speed based on the BOG compression power adjustment period; An information acquisition module, which is used to acquire LNG terminal information, LNG terminal structure information, and structure parameter information corresponding to each LNG terminal structure. Based on the LNG terminal information, it acquires the maximum storage height information of the LNG storage structure, acquires the LNG boiling point temperature information, acquires the LNG historical transmission data according to the LNG terminal information, and acquires the historical ambient temperature information, the BOG historical generation rate information corresponding to the historical ambient temperature, and the LNG liquid level height information according to the LNG historical transmission data; An evaluation module, which is used to use the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient. According to the BOG historical generation rate information and the liquid level correction coefficient, it acquires the BOG historical corrected generation rate, and uses the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient. According to the LNG temperature influence data group, it screens the ambient temperature influence coefficient based on the historical ambient temperature to acquire the ambient temperature influence reference coefficient, takes the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient, matches the BOG historical corrected generation rate corresponding to each historical ambient temperature with the ambient temperature influence coefficient, takes the difference between the two historical ambient temperatures corresponding to the minimum temperature difference recognition coefficient as the temperature difference reference value, and based on the historical ambient temperature information and the LNG boiling point temperature information, takes the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature. Based on the historical characteristic ambient temperature, it uses the temperature difference reference value as the historical ambient temperature change threshold to group the LNG historical transmission data to acquire the LNG temperature influence data group; A display module, which interacts with the main control module and is used to output and display the LNG terminal information, the BOG temperature influence coefficient, the ambient temperature information, the LNG transmission speed information, and the BOG compression power adjustment period.

8. A control system for processing a liquefied natural gas stream at an LNG import terminal, characterized in that, The main control module specifically includes: A control unit, which is used to establish a coordinate system for each LNG historical transmission data set, with the historical ambient temperature as the abscissa and the difference between the BOG historical generation rate and the BOG historical generation characteristic rate corresponding to the historical ambient temperature as the ordinate, to acquire the BOG temperature influence evaluation difference curve. According to the LNG transmission speed information and the BOG compression power standard adjustment value, it acquires the BOG compression power adjustment period, and based on the BOG compression power adjustment period, it adjusts the BOG compression power and the LNG transmission speed; An information receiving unit, which interacts with the information acquisition module and the evaluation module and is used to receive data and transmit it to the data processing unit; A data processing unit, which is used to fit the BOG temperature influence evaluation difference curve with a linear equation, take the one with the minimum slope as the LNG historical transmission feature data set, establish a BOG historical generation function with time as a variable according to the BOG compression power data and BOG historical generation rate information in the LNG historical transmission feature data set, obtain the storage structure historical pressure data according to the LNG historical transmission data, obtain the BOG compression conversion coefficient based on the BOG historical generation function and the storage structure historical pressure data, and obtain the LNG transmission speed information according to the BOG compression conversion coefficient.

9. A control system for processing a liquefied natural gas stream at an LNG import terminal, characterized in that, The information acquisition module specifically includes: A first acquisition unit, which is used to acquire LNG terminal information, LNG terminal structure information and structure parameter information corresponding to each LNG terminal structure, obtain the maximum storage height information of the LNG storage structure based on the LNG terminal information, and obtain the LNG boiling point temperature information; A second acquisition unit, which is used to acquire LNG historical transmission data according to the LNG terminal information, and obtain historical ambient temperature information, BOG historical generation rate information corresponding to the historical ambient temperature and LNG liquid level height information according to the LNG historical transmission data.

10. A control system for processing a liquefied natural gas stream at an LNG import terminal, characterized in that, The evaluation module specifically includes: A first evaluation unit, which is used to take the ratio of the LNG liquid level height to the maximum storage height as the liquid level correction coefficient, obtain the BOG historical corrected generation rate according to the BOG historical generation rate information and the liquid level correction coefficient, take the ratio of the BOG historical corrected generation rate to the difference between the corresponding historical ambient temperature and the LNG boiling point temperature as the ambient temperature influence coefficient, screen the ambient temperature influence coefficient based on the historical ambient temperature according to the LNG temperature influence data group, obtain the ambient temperature influence reference coefficient, and take the average value of the ambient temperature influence reference coefficient as the BOG temperature influence coefficient; A second evaluation unit, which is used to correspond and match the BOG historical corrected generation rate corresponding to each historical ambient temperature and the ambient temperature influence coefficient, take the difference between the two historical ambient temperatures corresponding to the minimum temperature difference identification coefficient as the temperature difference reference value, take the historical ambient temperature closest to the LNG boiling point temperature in the historical ambient temperature information as the historical characteristic ambient temperature based on the historical ambient temperature information and the LNG boiling point temperature information, group the LNG historical transmission data based on the historical characteristic ambient temperature with the temperature difference reference value as the historical ambient temperature change threshold, and obtain the LNG temperature influence data group.

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