LNG storage tank density layered monitoring system and method
By using mobile sensors and intelligent processor systems, combined with dynamic thresholds and density change models, the problems of data redundancy and interface positioning errors in LNG storage tank density stratification monitoring have been solved, achieving efficient and accurate density stratification monitoring and improving tank safety and operational efficiency.
Patent Information
- Application Number
- CN202511409089.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2026-01-20
AI Technical Summary
Existing methods for monitoring the density stratification of LNG storage tanks suffer from data redundancy due to fixed-interval measuring points and large interface positioning errors, making it impossible to accurately capture thin density abrupt changes and affecting the accuracy of rollover prediction.
Employing a mobile sensor and intelligent processor system, the system identifies suspected stratified areas through density gradient analysis and dynamic thresholds, proactively increases measurement points, and predicts interface locations using a preset density change model, thus achieving adaptive monitoring.
Precisely capturing the thin-layer density interface reduces the burden of data acquisition and processing, provides early stratification risk assessment, offers reliable decision-making basis for rollover prevention, and enhances the safety margin of storage tanks.
Smart Images
Figure CN121363711A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of liquefied natural gas (LNG) storage, and particularly relates to a LNG storage tank density stratification monitoring system and method. BACKGROUND
[0002] During the operation of a liquefied natural gas (LNG) storage tank, density stratification may occur due to the temperature and density differences between newly injected LNG and the original LNG in the tank, the "aging" of LNG components during storage (light components evaporate first, resulting in an increase in the density of the remaining liquid), and heat leakage from the tank wall. Specifically, the upper layer of LNG gradually becomes heavier due to heat leakage (the "weathering" effect), while the lower layer of LNG expands and its density decreases due to heating. When the density difference between the upper and lower layers of LNG decreases to a certain extent, the original stable stratification state in the tank may be disrupted, and a violent mixing, i.e., a "rollover" phenomenon, may occur. Rollover can cause a large amount of LNG to rapidly vaporize in a short period of time, resulting in a sudden increase in pressure in the tank, which may exceed the set value of the safety valve, causing a large amount of LNG vapor to be released into the atmosphere, not only causing economic losses, but also posing a serious safety threat to the tank structure and the surrounding environment. Therefore, accurate and real-time monitoring of the density stratification conditions inside the LNG storage tank is crucial for predicting and preventing rollover accidents, ensuring the safe operation of the tank, and improving operational efficiency. By monitoring the density and temperature profiles, signs of stratification can be detected in a timely manner, the stability of the stratification can be evaluated, and decision-making basis for taking mixing measures (such as circulation or injection) can be provided, thereby effectively avoiding the occurrence of rollover.
[0003] Existing monitoring of density stratification in LNG storage tanks mainly relies on the installation of multiple fixed density or temperature measurement points in the tank. For example, measurement points are arranged at intervals of 0.5 meters within a 20-meter-high liquid level range, and data from each point is obtained to analyze the density stratification conditions. However, this method has significant limitations. First, the density stratification in the LNG storage tank is essentially a continuous gradient change, and the density values of adjacent measurement points may be highly correlated (e.g., a difference of less than 0.5%) in the fixed interval measurement point data, resulting in a large amount of redundant data being collected, wasting storage and computing resources. Second, the core feature of density stratification is the "interlayer interface", i.e., the location where the density of the upper and lower layers changes abruptly. The fixed measurement point interval of 0.5 meters has a "blind spot" in space, and if the stratification interface is located between two measurement points (e.g., 0.25 meters, 2.75 meters, etc., which are not integer multiples of 0.5 meters), the measurement point data can only reflect the density values on both sides of the interface, but cannot accurately capture the actual location of the interface, with a positioning error of up to ±0.25 meters. For a thin density change layer (e.g., with a thickness of less than 0.5 meters), this fixed multi-point measurement method may even completely miss the thin layer, resulting in a misjudgment of the thin layer as a uniform layer, thereby causing serious errors in the identification of the stratification state and affecting the accuracy of rollover prediction. SUMMARY
[0004] The application provides a LNG storage tank density stratification monitoring system and method to solve the defects of the prior art.
[0005] The application provides a LNG storage tank density stratification monitoring system, comprising:
[0006] a sensor arranged to be longitudinally movable along the longitudinal axis of the LNG storage tank, for measuring the LNG density of a plurality of preset density measurement points in the LNG storage tank, and sending the LNG density signal to the processor;
[0007] a processor for receiving the LNG density signals sent by the sensor at the plurality of preset density measurement points respectively, and determining a suspected density stratification region according to the density gradient between the density signals corresponding to adjacent preset density measurement points, and issuing a moving instruction to the driving mechanism;
[0008] a driving mechanism for receiving the moving instruction issued by the processor, and driving the sensor to move up and down along the longitudinal axis of the LNG storage tank according to the moving instruction, and actively increasing the density measurement points in the suspected density stratification region.
[0009] According to the LNG storage tank density stratification monitoring system provided by the application, the LNG density signals sent by the sensor at the plurality of preset density measurement points are received, and a suspected density stratification region is determined according to the density gradient between the density signals corresponding to adjacent preset density measurement points, and a moving instruction is issued to the driving mechanism, comprising:
[0010] The LNG density signals sent by the sensor are preprocessed, and the preprocessing includes filtering and denoising.
[0011] According to the LNG storage tank density stratification monitoring system provided by the application, the LNG density signals sent by the sensor at the plurality of preset density measurement points are received, and a suspected density stratification region is determined according to the density gradient between the density signals corresponding to adjacent preset density measurement points, and a moving instruction is issued to the driving mechanism, comprising:
[0012] The density gradient between the density signals corresponding to adjacent preset density measurement points is obtained according to the LNG density signals sent by the sensor at the plurality of preset density measurement points;
[0013] The density gradient between the density signals corresponding to adjacent preset density measurement points is compared with a dynamic threshold value, and when the density gradient is greater than the dynamic threshold value, it is determined that the region where the density gradient is located is a suspected density stratification region.
[0014] The LNG storage tank density stratification monitoring system provided by the application, the dynamic threshold is dynamically determined based on at least one of the following factors: historical density gradient data statistical characteristics in the LNG storage tank, real-time operation conditions of the LNG storage tank, predicted values based on a physical model, or outputs of a machine learning model.
[0015] The LNG storage tank density stratification monitoring system provided by the application, the expression of the dynamic threshold is:
[0016]
[0017] In the formula, Threshold dynamic (h, t) represents the dynamic threshold of the LNG density at the height h and the time t of the position of the sensor, represents the standard deviation of the current density gradient value (which can be calculated within a certain time window), reflecting the natural fluctuation amplitude of the density in the region, k represents an adjustable coefficient (usually 2 or 3), which is similar to the "3σ principle" in statistics, and is used to determine the abnormal boundary, represents the absolute value of the gradient of the background expected density profile, ensuring that the threshold can adapt to the inherent and stable density stratification structure in the storage tank, and when the real-time measured density gradient exceeds Threshold dynamic (h, t), it is determined that the suspected density stratification region.
[0018] The LNG storage tank density stratification monitoring system provided by the application, the receiving sensor respectively sends the LNG density signals of a plurality of preset density measurement points, and determines the suspected density stratification region according to the density gradient between the density signals corresponding to adjacent preset density measurement points, and issues a moving instruction to the driving mechanism, comprising:
[0019] According to the density gradient of the suspected density stratification region, the possible position of the density stratification interface is predicted through a preset density change model, a new density measurement point is set, and a moving instruction is issued to the driving mechanism.
[0020] The LNG storage tank density stratification monitoring system provided by the application, the preset density change model is any one of the following: a parameterized function model fitted based on historical and real-time data, a numerical calculation model based on interpolation of measurement points, or a physical prediction model based on fluid mechanics principles.
[0021] The LNG storage tank density stratification monitoring system provided by the application, the preset density change model is an S-shaped function model, which predicts the center position and steepness of the density mutation interface by fitting the density measurement values on both sides of the suspected stratification region as boundary conditions, and then guides the setting of the new density measurement point.
[0022] The LNG storage tank density stratification monitoring system provided by the application, a preset density change model processes data of all available measurement points by a cubic spline interpolation method, generates a continuous density profile and a gradient distribution thereof, and determines the position of a newly added density measurement point by finding a gradient extreme point.
[0023] The LNG storage tank density stratification monitoring system provided by the application, a preset density change model is a simplified one-dimensional physical model that integrates heat leakage and component evaporation effects, and the model can not only locate a current interface but also predict an evolution trend of the interface, thereby realizing adaptive monitoring.
[0024] The LNG storage tank density stratification monitoring system provided by the application, a driving mechanism includes a control arm and a guide rail, the sensor is arranged on the guide rail and can move along the guide rail, and the control arm is used for receiving a movement instruction issued by the processor and driving the sensor to move along the guide rail according to the movement instruction, so that the density measurement point in the suspected density stratification region is actively added.
[0025] The application further provides an LNG storage tank density stratification monitoring method, which is realized based on the LNG storage tank density stratification monitoring system.
[0026] S1, a plurality of original density measurement points are arranged in a target LNG storage tank along a longitudinal direction of the target LNG storage tank.
[0027] S2, the sensor is used to move along the longitudinal direction of the target LNG storage tank, LNG densities of the plurality of original density measurement points are measured respectively, and LNG density signals of the plurality of original density measurement points are sent to the processor.
[0028] S3, the processor is used to determine a suspected density stratification region according to a density gradient between adjacent original density measurement points, and a movement instruction is issued to the driving mechanism.
[0029] S4, the driving mechanism is used to drive the sensor to move along the longitudinal direction of the target LNG storage tank according to the movement instruction, so that a density measurement point in the suspected density stratification region is actively added.
[0030] S5, the sensor is used to measure LNG densities in the suspected density stratification region at the newly added density measurement point in the suspected density stratification region, and S2-S4 are repeatedly executed until there is no suspected density stratification region, so that a position of an LNG density stratification interface is obtained.
[0031] The LNG storage tank density stratification monitoring method provided by the application, the plurality of original density measurement points are equidistantly distributed along the longitudinal direction of the target LNG storage tank.
[0032] The LNG storage tank density stratification monitoring system and method provided by the application have at least the following beneficial effects:
[0033] (1) Through the cooperation of sensors and intelligent processors, the passive mode of traditional fixed-point measurement is changed. When a suspected stratification area is found by preliminary measurement, the system can actively and accurately increase the measurement points inside the area to achieve "focused" encryption measurement of the density mutation layer. This adaptive measurement method completely solves the "space blind area" problem caused by fixed-point spacing, and can accurately capture the position and shape of thin layer interfaces with a thickness of less than 0.5 meters, effectively avoiding missed detection and misjudgment, and providing the most critical data basis for accurate prediction of rolling accidents.
[0034] (2) Introducing dynamic thresholds based on historical statistical data, real-time working conditions or physical models for gradient judgment, so that the system can intelligently distinguish between normal density fluctuations and dangerous stratification precursors. Combined with a pre-set density change model (such as S-shaped function fitting, spline interpolation, etc.) to predict the interface position, the sensor can move in a targeted manner. This "global scanning - intelligent identification - local focusing" working mode avoids unnecessary intensive measurement in uniform areas, greatly reducing the burden of data acquisition, transmission and processing, saving storage and computing resources, and making the monitoring system run more efficiently and economically.
[0035] (3) The formation and evolution of density stratification can be detected earlier and more accurately, so that the operator can assess the stratification stability risk more timely. Compared with the traditional method which may not be discovered until the stratification is severe, the accurate interface information provided by the present application provides an earlier and more reliable decision basis for taking mixed measures (such as starting the circulating pump, the injector), so as to curb the rolling risk in the embryonic state, greatly improving the safety margin of the storage tank operation.
[0036] (4) The dynamic threshold and the density change model can be customized and adaptively adjusted according to the specific size, operating parameters (such as feed frequency, heat leakage rate) of different storage tanks, rather than relying on fixed parameters. This makes the present application flexible to be applied to various types and working conditions of LNG storage tanks, with good universality and adaptability.
[0037] In summary, the present application innovates the traditional "static, uniform point distribution" monitoring mode to an "dynamic, adaptive point distribution" intelligent monitoring mode, fundamentally overcoming the inherent defects of the prior art, achieving more accurate, efficient and intelligent monitoring of LNG storage tank density stratification, and having crucial practical significance for ensuring the safe, stable and efficient operation of large LNG storage tanks. BRIEF DESCRIPTION OF DRAWINGS
[0038] In order to more clearly illustrate the technical solutions in the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.
[0039] Figure 1 A structural schematic diagram of an LNG storage tank density stratification monitoring system provided by the present application.
[0040] Figure 2 An application flowchart of an LNG storage tank density stratification monitoring system provided by the present application. DETAILED DESCRIPTION
[0041] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely in combination with the accompanying drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments, and they should not be understood as a limitation on the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application. In the description of the present application, it should be understood that the terms used are only for the purpose of description, and should not be understood as indicating or implying relative importance.
[0042] Referring to Figure 1 and Figure 2 , the LNG storage tank density stratification monitoring system provided by the present application can include:
[0043] A, a sensor arranged to be able to move longitudinally along the longitudinal axis of the LNG storage tank, for measuring the LNG density of a plurality of preset density measurement points in the LNG storage tank, and sending the LNG density signal to the processor;
[0044] B, a processor for receiving the LNG density signal sent by the sensor at a plurality of preset density measurement points respectively, and determining a suspected density stratification area according to the density gradient between the LNG density signals corresponding to adjacent preset density measurement points, and issuing a moving instruction to the driving mechanism.
[0045] In an embodiment, the processor can perform filtering, denoising and other preprocessing on the LNG density signal after receiving it, so as to improve the data accuracy.
[0046] In an embodiment, the processor can obtain a density gradient between the density signals corresponding to adjacent preset density measurement points according to the LNG density signals respectively sent by the sensors at the preset density measurement points; compare the density gradient between the density signals corresponding to adjacent preset density measurement points with a dynamic threshold value; when the density gradient is greater than the dynamic threshold value, determine that a region where the density gradient is located is a suspected density stratification region; and according to the density gradient of the suspected density stratification region, predict a possible position of a density stratification interface through a preset density change model, set a new density measurement point, and send a moving instruction to the driving mechanism.
[0047] The dynamic threshold value is dynamically determined based on at least one of the following factors: historical density gradient data statistical characteristics in the LNG storage tank, real-time running conditions of the LNG storage tank, a predicted value based on a physical model, or an output of a machine learning model.
[0048] In the embodiment, a background density profile can be established first:
[0049] When the storage tank is in a stable state (e.g., after sufficient mixing after feeding, without rolling risk), the sensor is controlled to perform a high-precision full-liquid-level scanning to obtain a reference density profile base(h) , where h is the height of the position where the sensor is located from the ground. In subsequent normal operation, the background profile is updated regularly (e.g., every hour) or continuously through sensor data (especially in uniform regions determined to be free of stratification). Moving average, exponential weighted moving average, or other algorithms can be used to smooth out normal minor fluctuations to form a background expected density profile expected(h,t) at the current time.
[0050] The dynamic threshold value Threshold dynamic (h, t) can be set as the gradient value of the background density profile at the corresponding height plus a statistical tolerance to obtain the expression of the dynamic threshold value:
[0051]
[0052] In the formula, Threshold dynamic (h, t) represents the dynamic threshold value of the LNG density at height h and time t, represents the standard deviation of the current density gradient value (which can be calculated within a certain time window), reflecting the natural fluctuation amplitude of the density in the region, and k represents an adjustable coefficient (usually 2 or 3), which is similar to the "3σ principle" in statistics, for determining the abnormal boundary, represents the absolute value of the gradient of the background expected density profile, ensuring that the threshold value can adapt to the inherent and stable density stratification structure in the storage tank, and when the real-time measured density gradient exceeds Thresholddynamic (h, t) time, that is, the suspected density stratification region is determined.
[0053] wherein the preset density variation model is any one of: a parameterized function model fitted based on historical and real-time data, a numerical calculation model based on interpolation of measurement points, or a physical prediction model based on fluid mechanics principles.
[0054] In this embodiment, the preset density variation model is an S-shaped function model (logistic function or error function), which is fitted by taking the density measurement values on both sides of the suspected stratification region as boundary conditions (using the nonlinear least squares method) to predict the center position and steepness of the density mutation interface, thereby guiding the setting of the new density measurement point.
[0055] In another embodiment, the preset density variation model is a simplified one-dimensional physical model (based on convection-diffusion equation) that incorporates heat leakage and component evaporation effects, which can not only locate the current interface but also predict its evolution trend, thereby realizing adaptive monitoring. Specifically, historical data and continuous monitoring data within a short time can be used to invert the most uncertain key parameters in the model, such as the effective diffusion coefficient D, the convection velocity u, and the strength of the source term S, through data assimilation techniques (such as four-dimensional variational assimilation 4D-Var or ensemble Kalman filter EnKF). The goal is to make the model simulation of density evolution most consistent with the measured values. Using the calibrated model and the current state as initial conditions, the equation is integrated forward to predict the density distribution in the future. Analyzing the density gradient in the prediction result can not only locate the current interface but also predict whether the interface will move up, move down, become steeper, or tend to dissipate. According to the predicted evolution trend, the monitoring strategy can be adjusted adaptively. For example, if the interface is predicted to move upwards, the sensor can be instructed to move to the predicted position in advance to achieve forward-looking point placement.
[0056] Alternatively, the preset density variation model processes the data of all available measurement points through cubic spline interpolation to generate a continuous density profile and its gradient distribution, and determines the position of the new density measurement point by finding the gradient extreme point. Specifically, the density values measured by all available sensors at different heights are collected, and a three-diagonal linear equation system is solved, which is composed of preset continuity conditions and boundary conditions (for example, the second derivatives at both ends are specified to be 0, called natural spline). This process is deterministic, and mature and efficient algorithms (such as Thomas algorithm) can be used to solve the continuous density gradient function. Then by solving the extreme point, the point with the maximum gradient can be accurately found, which is the position of the most severe density mutation, and the new measurement point can be set at the depth corresponding to this extreme point.
[0057] C. a driving mechanism configured to receive the movement instruction from the processor and drive the sensor to move up and down along the longitudinal axis of the LNG storage tank according to the movement instruction, so as to actively increase the density measurement points in the suspected density stratification area.
[0058] In an embodiment, the driving mechanism comprises a control arm and a guide rail, the sensor is arranged on the guide rail and is capable of moving along the guide rail, and the control arm is configured to receive the movement instruction from the processor and drive the sensor to move longitudinally along the longitudinal axis of the LNG storage tank according to the movement instruction, so as to actively increase the density measurement points in the suspected density stratification area.
[0059] Based on the LNG storage tank density stratification monitoring system described above, an LNG storage tank density stratification monitoring method can be formed, comprising:
[0060] S1. arranging a plurality of original density measurement points in the target LNG storage tank along the longitudinal direction of the target LNG storage tank;
[0061] S2. moving the sensor along the longitudinal direction of the target LNG storage tank to measure the LNG density of each of the original density measurement points, and sending the LNG density signals of the original density measurement points to the processor;
[0062] S3. determining the suspected density stratification area according to the density gradient between adjacent original density measurement points by the processor, and sending a movement instruction to the driving mechanism;
[0063] S4. driving the sensor to move along the longitudinal direction of the target LNG storage tank according to the movement instruction by the driving mechanism, so as to actively increase the density measurement points in the suspected density stratification area;
[0064] S5. measuring the LNG density in the suspected density stratification area by the sensor at the newly added density measurement points in the suspected density stratification area, repeating S2-S4 until there is no suspected density stratification area, and obtaining the position of the LNG density stratification interface.
[0065] The application provides a LNG storage tank density stratification monitoring system and method. By introducing a dynamic measuring point optimization mechanism, the monitoring mode is innovated from the traditional "static uniform point distribution" to "dynamic self-adaptive focusing", which significantly improves the monitoring efficiency of the density stratification in the LNG storage tank. Specifically, the system can intelligently encrypt measuring points in the initially identified "abnormal interval", and preferentially invests measuring resources in the key area, so as to accurately capture the position and form of the thin layer density interface, completely eliminates the spatial blind area of the fixed point distribution mode, and the local measuring point spacing can be much better than the initial setting (such as from 0.5 meters to 0.125 meters), and higher resolution density gradient information is obtained. The strategy of "initial survey, local focusing" is adopted to avoid invalid measurement in the flat area, and the core stratification characteristics are quickly locked in a "targeted" manner, which is more efficient than the traditional full-tank high-density scanning or repeated investigation. By providing higher timeliness and higher resolution density profile data, more accurate input is provided for the anti-rollover prediction software, so that the prediction model can identify risks earlier and more reliably, and valuable time is gained for taking proactive prevention measures, and the safety operation guarantee capability of the storage tank is fundamentally improved.
[0066] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.
Claims
1. A density stratification monitoring system for LNG storage tanks, characterized in that, include: The sensor is configured to move longitudinally along the longitudinal axis of the LNG storage tank to measure the LNG density at multiple preset density measurement points inside the LNG storage tank and send the LNG density signal to the processor. The processor is used to receive LNG density signals sent by the sensor at multiple preset density measurement points, and to determine the suspected density stratification area based on the density gradient between the density signals corresponding to adjacent preset density measurement points, and to issue a movement command to the drive mechanism. The drive mechanism receives movement commands from the processor and drives the sensor to move up and down along the longitudinal axis of the LNG storage tank according to the movement commands, actively increasing the density measurement points in the suspected density stratification area.
2. The LNG storage tank density stratification monitoring system according to claim 2, characterized in that, The receiving sensor receives LNG density signals from multiple preset density measurement points, and determines suspected density stratification regions based on the density gradient between density signals corresponding to adjacent preset density measurement points. It then issues a movement command to the drive mechanism, including: Based on the LNG density signals sent by the sensor at multiple preset density measurement points, the density gradient between the density signals corresponding to adjacent preset density measurement points is obtained; The density gradient between the density signals corresponding to adjacent preset density measurement points is compared with a dynamic threshold. When the density gradient is greater than the dynamic threshold, the region where the density gradient is located is determined to be a suspected density stratification region.
3. The LNG storage tank density stratification monitoring system according to claim 3, characterized in that, The dynamic threshold is dynamically determined based on at least one of the following factors: statistical characteristics of historical density gradient data in the LNG storage tank, real-time operating conditions of the LNG storage tank, predicted values based on a physical model, or the output of a machine learning model.
4. The LNG storage tank density stratification monitoring system according to claim 4, characterized in that, The expression for the dynamic threshold is: In the formula, Threshold dynamic (h,t) represents the dynamic threshold of LNG density at the height h and time t of the sensor location. The standard deviation of the current density gradient value is represented by k, which is an adjustable coefficient used to determine the anomaly boundary. This represents the absolute value of the gradient of the background desired density profile.
5. The LNG storage tank density stratification monitoring system according to claim 3, characterized in that, The receiving sensor receives LNG density signals from multiple preset density measurement points, and determines suspected density stratification regions based on the density gradient between density signals corresponding to adjacent preset density measurement points. It then issues a movement command to the drive mechanism, including: Based on the density gradient of the suspected density stratification area, the possible location of the density stratification interface is predicted by using a preset density change model, new density measurement points are set, and movement commands are sent to the drive mechanism.
6. The LNG storage tank density stratification monitoring system according to claim 5, characterized in that, The preset density change model can be any of the following: a parameterized function model based on fitting historical and real-time data, a numerical calculation model based on measurement point interpolation, or a physical prediction model based on fluid dynamics principles.
7. The LNG storage tank density stratification monitoring system according to claim 6, characterized in that, The preset density change model is an S-shaped function model, which uses density measurements on both sides of the suspected stratified region as boundary conditions to predict the center position and steepness of the density abrupt change interface, thereby guiding the setting of new density measurement points.
8. The LNG storage tank density stratification monitoring system according to any one of claims 1-7, characterized in that, The drive mechanism includes a control arm and a guide rail. The sensor is mounted on the guide rail and can move along the guide rail. The control arm is used to receive movement commands from the processor and drive the sensor to move along the guide rail according to the movement commands, thereby realizing the active increase of density measurement points in the suspected density stratification area.
9. A method for stratified density monitoring of LNG storage tanks, characterized in that, Based on the LNG storage tank density stratification monitoring system according to any one of claims 1-8, the method includes: S1. Along the longitudinal direction of the target LNG storage tank, set up multiple original density measurement points inside the target LNG storage tank; S2. Using sensors to move longitudinally along the target LNG storage tank, the LNG density at multiple raw density measurement points is measured, and the LNG density signals at multiple raw density measurement points are sent to the processor. S3. The processor determines the suspected density stratification region based on the density gradient between adjacent original density measurement points and sends a movement command to the drive mechanism. S4. Drive the sensor along the longitudinal direction of the target LNG storage tank according to the movement command through the drive mechanism to actively increase the density measurement points in the suspected density stratification area. S5. Measure the LNG density in the suspected density stratification area using the newly added density measurement point in the suspected density stratification area using the sensor. Repeat S2-S4 until there are no more suspected density stratification areas, and obtain the location of the LNG density stratification interface.
10. The LNG storage tank density stratification monitoring method according to claim 9, characterized in that, Multiple original density measurement points are equidistantly distributed along the longitudinal direction of the target LNG storage tank.