A cold-insulation monitoring system and a monitoring method for a thin-film type storage device

Abstract

The application discloses a cold insulation monitoring system and a monitoring method of a thin film type storage device, which comprises an ambient temperature sensor, a first temperature sensor embedded in a cabin plate, a second temperature sensor embedded in a secondary insulation layer, a third temperature sensor embedded in a primary insulation layer, and a liquid cargo temperature sensor. In a monitoring chain, the first, second and third temperature sensors are located in a cylindrical space with a straight line perpendicular to the plane of the cabin plate as an axis. A temperature monitoring unit calculates a temperature gradient and a heat flow density in real time, evaluates the heat insulation performance layer by layer, and identifies a defective layer position. The application solves the defect that the prior art can only obtain a single point temperature and cannot present a full cross-section temperature gradient, and realizes real-time online quantitative monitoring and layer position diagnosis of the cold insulation performance of a multi-layer heat insulation structure.

Description

Technical Field

[0001] This invention relates to the field of cryogenic storage devices for refrigerated liquefied gases, and more specifically to a cold preservation monitoring system and method for a thin-film storage device. Background Technology

[0002] Membrane-type storage tanks are widely used for the storage and transportation of cryogenic liquids such as liquefied natural gas (LNG). The continuous effectiveness of their insulation performance directly affects the control of evaporation loss and structural safety. Existing technologies for monitoring the insulation performance of in-service membrane-type storage tanks mainly include: real-time calculation of the evaporation rate based on the gas flow rate of the evaporator compressor and monthly comparison with the design value; infrared thermal imaging scanning of the tank's outer wall during shutdown or low liquid level windows; periodic extraction of gas from the primary and secondary shielding layers to detect water content and air composition; and attaching temperature sensors to the outer surfaces of the primary and secondary shielding layers or inserting them into the interlayer through a dedicated flange to directly measure the temperature of the interlayer medium.

[0003] However, the above-mentioned technical solutions share common shortcomings. First, existing methods mostly rely on shutdown maintenance windows or periodic sampling, making it difficult to achieve continuous online monitoring under normal operating conditions of the storage tank. Second, existing temperature measurement methods can only obtain temperature values ​​at a limited number of discrete measurement points on the film plane, failing to present the cross-sectional temperature gradient distribution formed by heat conduction along the thickness direction of the insulation layer—from the liquid cargo side through the main shield, the interlayer insulation layer, the secondary shield to the outer structure—layer by layer. Therefore, it is impossible to determine the actual thermal resistance state of each insulation functional layer, accurately locate the layer where insulation failure occurs, and furthermore, it is difficult to distinguish between the two fundamentally different failure modes of film damage and insulation material performance degradation in the early stages.

[0004] In view of this, it is necessary to provide a system that can monitor the temperature of the cold insulation section of a membrane-type storage tank in real time, continuously, and across the entire temperature gradient without interrupting production, in order to overcome the aforementioned deficiencies of the prior art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing temperature measurement methods for thin-film storage devices can only obtain single-point temperature and cannot present the complete temperature gradient change from the cryogenic liquid to the external environment, making it difficult to verify the thermal insulation performance of the film. The present invention provides a cold-keeping monitoring system and monitoring method that can continuously measure the temperature gradient and realize online evaluation of thermal insulation performance.

[0006] To address the aforementioned technical problems, this invention provides a cold-keeping monitoring system for thin-film storage devices:

[0007] The storage device consists of, from the outside to the inside, a body plate, a secondary insulating layer, a secondary shielding layer, a primary insulating layer, a primary shielding layer, and a storage space. The secondary insulating layer is fixed to the inside of the body plate. The secondary shielding layer covers the upper surface of the secondary insulating layer. The primary insulating layer is laid on top of the secondary shielding layer. The primary shielding layer covers the upper surface of the primary insulating layer.

[0008] The cold preservation monitoring system includes multiple monitoring chains, and each monitoring chain includes:

[0009] An ambient temperature sensor is installed outside the cabin panel to collect a reference value of the atmospheric ambient temperature outside the storage device.

[0010] A first temperature sensor is embedded in the cabin panel to collect the temperature of the cabin panel;

[0011] A first temperature measuring group, the first temperature measuring group includes at least one second temperature sensor, the second temperature sensor being embedded in the secondary insulating layer;

[0012] The second temperature measuring group includes at least one third temperature sensor, which is embedded in the main insulating layer.

[0013] A liquid cargo temperature sensor is installed inside the storage space to collect the temperature of the liquid cargo inside the storage space.

[0014] The first temperature sensor, the first temperature measuring group, and the second temperature measuring group are located in the same cylindrical space with a straight line perpendicular to the plane of the cabin plate as the axis.

[0015] The cold storage monitoring system also includes a temperature monitoring unit, wherein the ambient temperature sensor, the first temperature sensor, the first temperature measuring group, the second temperature measuring group, and the liquid cargo temperature sensor are respectively connected to the temperature monitoring unit via signal lines.

[0016] Furthermore, multiple monitoring chains share one ambient temperature sensor and one liquid cargo temperature sensor. In each monitoring chain, there is one first temperature sensor, and the first temperature measurement group and the second temperature measurement group are respectively equipped with at least one second temperature sensor and a third temperature sensor.

[0017] Furthermore, both the secondary insulation layer and the primary insulation layer are composed of multiple insulation blocks spliced ​​together, and the first temperature measuring group and the second temperature measuring group are located in the splicing gap between adjacent insulation blocks.

[0018] Furthermore, at least three of the second temperature sensor and the third temperature sensor are respectively provided along the thickness direction of the insulating block.

[0019] Furthermore, the wiring harness of the second temperature sensor extends outward from the corresponding mounting position of the first temperature sensor.

[0020] Furthermore, the secondary shielding layer is corrugated, and the corrugations protrude toward the secondary insulating layer. The wiring harness of the third temperature sensor is arranged in the accommodating gap between the main shielding layer and the secondary shielding layer. After the wiring harnesses of multiple second temperature measuring groups are gathered together, they are uniformly led out from one exit position of the secondary shielding layer and the cabin plate.

[0021] Furthermore, the liquid cargo temperature sensor, the first temperature sensor, the first temperature measuring group, and the second temperature measuring group are all equipped with vacuum-sealed joints at the through-hole positions between the main shielding layer, the secondary shielding layer, and the cabin plate.

[0022] Furthermore, the cold preservation monitoring system is located in a corner area of ​​the storage device.

[0023] Furthermore, the cold storage monitoring system is installed on the top surface of the LNG carrier's cargo tank.

[0024] The present invention also provides a method for monitoring the cold storage of a thin-film storage device, comprising the following steps:

[0025] S10: Centralized acquisition and preprocessing of temperature data: All temperature signals are acquired synchronously at a preset frequency, and after analog-to-digital conversion and digital filtering, they are stored in the local database and synchronously transmitted to the data processing terminal.

[0026] S20: Real-time temperature data display: Displays the real-time temperature values ​​of each measuring point on the industrial display screen interface of the display and alarm terminal in real time;

[0027] S30: Temperature distribution curve and temperature gradient calculation: Draw the temperature distribution map of each temperature measuring point and calculate the temperature gradient between each two adjacent measuring points;

[0028] S40: Heat flux density calculation: Calculate the local heat flux density through each insulation layer according to Fourier's law of thermal conductivity;

[0029] S50: Insulation layer performance evaluation: Based on the heat flux density and temperature difference data of each layer obtained in step S40, the equivalent thermal resistance value of each functional layer is further calculated. The equivalent thermal resistance value is compared with the design reference thermal resistance value of the functional layer layer by layer to evaluate the insulation performance.

[0030] S60: Identification and diagnosis of insulation defects: Identification and diagnosis of insulation defects are performed based on the results of the layer-by-layer evaluation in step S50.

[0031] S70: Long-term trend analysis and early warning: Establish temperature databases for each monitoring chain, perform linear or exponential regression trend fitting on the change trajectory of equivalent thermal resistance values ​​of each layer over time, predict the degradation rate of insulation performance of each functional layer and the expected time to reach the next performance degradation threshold level, and issue early warnings.

[0032] The beneficial effects of this invention are:

[0033] By constructing a structure of "multi-layer temperature array + full-thickness temperature gradient reconstruction + online evaluation of insulation performance," the technical problem of existing technologies being unable to present complete temperature gradient changes has been completely solved. By setting up a complete temperature measurement chain at each monitoring point, a continuous temperature gradient curve along the film thickness direction can be generated in real time. The heat flux density and equivalent thermal resistance of each functional layer can be accurately quantified and calculated, and the internal temperature field distribution of the multi-layer insulation structure can be realistically reproduced. This provides a scientific full-section measured data basis for the optimized design of insulation performance and reliability verification of thin-film cryogenic storage devices.

[0034] Components such as temperature sensors and vacuum-sealed joints only need to be embedded during the device manufacturing stage, without requiring major modifications to the existing membrane enclosure system. This results in low engineering modification costs and suitability for large-scale industrial applications. Furthermore, this invention can be applied to temperature field monitoring and insulation performance evaluation of LNG fuel tanks / cryogenic storage tanks, as well as other multi-layered insulated cryogenic containers such as liquid hydrogen, liquid nitrogen, liquid oxygen, and liquefied carbon dioxide. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0036] The following are the labeling instructions in the diagram: 1. Cabin panel; 2. Secondary insulation layer; 3. Secondary shielding layer; 4. Primary insulation layer; 5. Primary shielding layer; 6. Storage space; 7. Lower plywood; 8. Polyurethane layer; 9. Upper plywood; 10. Ambient temperature sensor; 11. First temperature sensor; 12. First temperature measuring group; 13. Second temperature sensor; 14. Second temperature measuring group; 15. Third temperature sensor; 16. Liquid cargo temperature sensor; 17. Temperature monitoring unit; 18. Vacuum sealing joint. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] Reference Figure 1The diagram shows a schematic representation of an embodiment of the cold storage monitoring system for the thin-film storage device of the present invention. In this embodiment, the storage device is the cargo tank of an LNG carrier. From the outside in, the storage device comprises: a tank body plate 1, a secondary insulation layer 2, a secondary shielding layer 3, a primary insulation layer 4, a primary shielding layer 5, and a storage space 6. The storage space 6 is the internal space of the cargo tank.

[0039] The cold storage monitoring system includes multiple monitoring chains arranged at preset intervals along the circumference of the storage unit's bulkhead. On each monitoring chain, along the thickness direction of the storage unit's wall, an ambient temperature sensor 10, a first temperature sensor 11, a first temperature measuring group 12, a second temperature measuring group 14, and a liquid cargo temperature sensor 16 are arranged sequentially. The first temperature sensor 11, the first temperature measuring group 12, and the second temperature measuring group 14 are located within a cylindrical space with an axis perpendicular to the plane of the bulkhead plate 1. The radius of the cylindrical space is smaller than the size of the insulating block, to ensure that the first temperature sensor 11, the first temperature measuring group 12, and the second temperature measuring group 14 are aligned longitudinally as much as possible. The ambient temperature sensor 10 and the liquid cargo temperature sensor 16 serve as global reference sensors, located on each monitoring chain, and their physical spatial deviation is not limited.

[0040] Specifically, the ambient temperature sensor 10 is installed on the outside of the cabin panel 1, in an area away from local heat sources such as cabin exhaust, to collect the ambient temperature reference value of the external atmosphere of the storage device in real time, and to serve as the "hot end" reference point for temperature gradient calculation.

[0041] A first temperature sensor 11 is embedded in the housing plate 1 at the position corresponding to the monitoring chain. Specifically, a through hole of suitable diameter is machined in the steel plate of the housing plate 1, and the temperature probe of the first temperature sensor 11 is embedded in the hole, so that the outer wall of the probe forms good thermal contact with the metal wall of the housing plate 1. A vacuum sealing joint 18 is installed at the through hole to ensure the airtightness of the hole and prevent air from flowing between the two sides of the housing plate 1.

[0042] The secondary insulation layer 2 is fixed to the inner surface of the cabin plate 1 and is composed of multiple insulation blocks tightly spliced ​​together along the planar direction. Each insulation block is a three-layer composite structure consisting of a lower plywood 7, a polyurethane layer 8, and an upper plywood 9. At least one second temperature sensor 13 is sequentially embedded from the outside to the inside in the vertical splicing gaps between adjacent insulation blocks, forming a first temperature measuring group 12. That is, one second temperature sensor 13 can be set in the first temperature measuring group 12. In this embodiment, given the thickness of the insulation blocks, at least three second temperature sensors 13 are set in each first temperature measuring group 12 to more accurately monitor the temperature gradient. The three second temperature sensors 13 are evenly arranged at approximately equal intervals along the thickness direction of the secondary insulation layer 2, located at the bottom of the secondary insulation layer 2 (near the lower plywood 7), the middle of the secondary insulation layer 2 (center of the polyurethane layer 8), and the top of the secondary insulation layer 2 (near the upper plywood 9), respectively. In this embodiment, the signal line of the second temperature sensor 13 is led out from the splicing seam and then from the mounting hole of the first temperature sensor 11 at the corresponding position on the same monitoring chain. After being collected, it is connected to the temperature monitoring unit 17. This centralized wiring method significantly reduces the number of openings on the cabin plate 1, which is beneficial for maintaining structural integrity and airtight boundaries.

[0043] The secondary shielding layer 3 is made of Invar steel or stainless steel sheet and covers the upper surface of the secondary insulation layer 2. In a preferred embodiment, the secondary shielding layer 3 can be provided with periodically undulating corrugations along the height direction, with the corrugations protruding towards the secondary insulation layer 2. This corrugation orientation provides two technical effects: firstly, the surface of the secondary shielding layer 3 facing the main insulation layer 4 remains flat, eliminating the need for clearance grooves corresponding to the corrugations on the lower surface of the main insulation layer 4, ensuring uniform thickness throughout the main insulation layer 4, and eliminating weak insulation areas formed by localized grooves; secondly, a continuous accommodating gap naturally forms between the back side of the corrugations and the bottom surface of the main insulation layer 4 along the corrugation extension direction.

[0044] The main insulation layer 4 is laid on top of the secondary shielding layer 3 and is composed of multiple insulating blocks spliced ​​together. Each insulating block has a three-layer composite structure similar to the secondary insulation layer 2, consisting of a lower plywood 7, a polyurethane layer 8, and an upper plywood 9. At least one third temperature sensor 15 is sequentially embedded from the outside to the inside in the splicing gaps between adjacent insulating blocks, forming a second temperature measuring group 14. That is, one third temperature sensor 15 can be set in the second temperature measuring group 14. In this embodiment, given the thickness of the insulating blocks, to more accurately monitor the temperature gradient, each second temperature measuring group 14 is equipped with at least three third temperature sensors 15. The three third temperature sensors 15 are evenly arranged along the thickness direction of the main insulation layer 4, located at the bottom of the corresponding lower plywood 7 position, the middle of the corresponding polyurethane layer 8 position, and the top of the corresponding upper plywood 9 position, respectively. In a preferred embodiment, the vertical spacing between the second temperature sensors 13 is the same as the vertical spacing between the third temperature sensors 15. In this case, if the thickness of the main insulating layer 4 is the same as the thickness of the secondary insulating layer 2, the number of second temperature sensors 13 and third temperature sensors 15 is the same. If the thickness of the secondary insulating layer 2 is greater than the thickness of the main insulating layer 4, the number of second temperature sensors 13 is greater than the number of third temperature sensors 15. Furthermore, after the signal line of the third temperature sensor 15 is led out from the splicing seam, it can pass through the lead hole reserved on the secondary shielding layer 3 and be led out from the mounting hole of the first temperature sensor 11 together with the signal line of the second temperature sensor 13 on the same monitoring chain. In this embodiment, in order to avoid the mounting hole of the first temperature sensor 11 being too large, the signal lines of the third temperature sensors 15 in multiple sets of second temperature measurement groups 14 are gathered together between the secondary shielding layer 3 and the main insulating layer 4, and the gathered signal lines are led out from a centralized exit hole of the secondary shielding layer 3 and the cabin plate 1.

[0045] The main shielding layer 5 covers the upper surface of the main insulation layer 4, and its inner surface is in direct contact with the LNG cargo inside the storage space 6, withstanding a cryogenic shock of approximately -163°C. Inside the storage space 6, specifically in the LNG immersion area, a cargo temperature sensor 16 is installed to directly detect the actual temperature of the cargo inside the compartment, serving as the "cold end" reference for temperature gradient calculation. The signal line of the cargo temperature sensor 16 passes through the main shielding layer 5, the secondary shielding layer 3, and the compartment plate 1 before exiting, with its lead-out length ensuring that the temperature signal attenuation remains within a preset range.

[0046] Preferably, the ambient temperature and the liquid cargo temperature remain almost constant throughout the system. Therefore, multiple monitoring chains in the entire cold storage monitoring system share a single ambient temperature sensor 10 and a single liquid cargo temperature sensor 16. On the same monitoring chain, the first temperature sensor 11, the first temperature measuring group 12, and the second temperature measuring group 14 are located within a cylinder with a straight line perpendicular to the plane of the hull plate 1 as its axis, to monitor the longitudinal temperature gradient changes in the same area. Since the distance between the hull plate 1 and the secondary insulation layer 2 is relatively small on each monitoring chain, only one first temperature sensor 11 is required. However, the insulation block has a certain thickness, so the first temperature measuring group 12 and the second temperature measuring group 14 are each equipped with multiple second temperature sensors 13 and third temperature sensors 15. Taking the example of three second temperature sensors 13 and three third temperature sensors 15 in this embodiment, along the thickness direction, from the outside to the inside, there are: ambient temperature sensor 10, first temperature sensor 11, three second temperature sensors 13, three third temperature sensors 15, and liquid cargo temperature sensor 16, forming a complete 9-point temperature monitoring chain, forming a through-type temperature gradient sensing channel from the external environment to the low-temperature liquid cargo.

[0047] The corner area of ​​the storage space, i.e., the angle between two surfaces, is a weak point for thermal shock in the storage space. It not only experiences stress concentration but also poses a significant risk of leakage. Therefore, in embodiments of the present invention, the monitoring system must be installed in at least this area. In other embodiments of the present invention, the monitoring system is also installed on the top surface of the LNG carrier's cargo tank. Because the top surface of the cargo tank is the deck, it experiences frequent personnel activity and is subjected to stress, significantly impacting its lifespan. Therefore, a monitoring system is installed on this surface for long-term monitoring.

[0048] Vacuum sealing joints 18 are installed at all perforation locations between the liquid cargo temperature sensor 16, the first temperature sensor 11, the first temperature measuring group 12, and the second temperature measuring group 14, between the main shielding layer 5, the secondary shielding layer 3, and the cabin plate 1. Furthermore, after all vacuum sealing joints 18 are installed, the vacuum level or inert gas pressure test is performed on the interlayer space between the main shielding layer 5 and the secondary shielding layer 3 to ensure that the protected sealed space maintains its design state for a long period.

[0049] In this embodiment, all temperature sensors, including ambient temperature sensor 10, first temperature sensor 11, second temperature sensor 13, third temperature sensor 15, and liquid cargo temperature sensor 16, are PT100 temperature sensors. The signal lines are made of low-temperature resistant polytetrafluoroethylene shielded cables, and a four-wire connection method is used to eliminate the measurement error introduced by the wire resistance.

[0050] The temperature monitoring unit 17 consists of a data acquisition unit, a data processing terminal, and a display and alarm terminal. The method for monitoring using the above-mentioned cold-keeping monitoring system includes the following steps.

[0051] S10. Centralized Acquisition and Preprocessing of Temperature Data. The data acquisition unit synchronously acquires temperature signals from all temperature sensors on all monitoring chains at a preset sampling frequency, including the ambient temperature sensor, the first temperature sensor, all second temperature sensors in the first temperature measurement group, all third temperature sensors in the second temperature measurement group, and the liquid cargo temperature sensor. The data acquisition unit performs analog-to-digital conversion and digital filtering on the raw electrical signals of each channel, eliminating gross error data caused by occasional factors such as electromagnetic interference and momentary poor sensor contact. After adding timestamps and channel identifiers to the valid temperature data, the data is stored in the local database and synchronously transmitted to the data processing terminal.

[0052] Taking any monitoring chain in this embodiment as an example, the data acquisition unit synchronously obtains 7 basically collinear temperature data points in the monitoring chain, and combines them with two global reference temperature values ​​to form the following logical 9-point temperature dataset: the temperature value T of the ambient temperature sensor. env The temperature value T1 of the first temperature sensor, and the temperature values ​​T from the outside to the inside of the three second temperature sensors in the first temperature measuring group. 2a T 2b T 2c The temperature values ​​T from the outside to the inside of the three third temperature sensors within the second temperature measuring group of this cross section. 3a T 3b T 3c And the temperature value T of the liquid cargo temperature sensor cargo .

[0053] S20. Real-time temperature data display. The data processing terminal displays the real-time temperature values ​​of each measuring point in the form of a digital table and / or a pseudo-color temperature field distribution map on the industrial touchscreen interface of the display and alarm terminal. The pseudo-color temperature field distribution map uses the unfolded plane of the storage tank's insulation structure as the background, with each measuring point filled in with the color corresponding to its temperature range, allowing operators to clearly understand the temperature distribution of each area of ​​the entire storage tank's insulation surface. Simultaneously, the system provides separate display areas for the liquid temperature and ambient temperature on the interface, allowing operators to quickly confirm whether the cold and hot end references are within the normal range.

[0054] S30. Temperature Distribution Curve and Temperature Gradient Calculation. The data processing terminal plots a discrete temperature distribution along the thickness of the storage device's bulkhead using the normal distance from each temperature measuring point to the liquid cargo interface as the abscissa (x), where in this embodiment the inner surface of the main shielding layer is used as the liquid cargo interface, and the measured temperature value T as the ordinate. The data processing terminal calculates the temperature gradient between any two adjacent measuring points. For any adjacent i-th measuring point and i+1-th measuring point, the temperature gradient grad is calculated. i =(T i -T i+1 ) / Δxi, where Ti T represents the temperature value at the measuring point closest to the liquid cargo side. i+1 The temperature value at the measuring point closest to the external environment, Δx i The normal center distance between the two measuring points. Since the temperature monotonically increases along the thickness direction from the cold end to the hot end, the temperature gradient grad... i The value is positive, and its physical meaning is the temperature rise per unit length along the thickness direction. Furthermore, the data processing terminal can also use the continuous temperature distribution function T(x) obtained through interpolation fitting to calculate the instantaneous temperature gradient dT / dx at any thickness position x using analytical or numerical differentiation methods.

[0055] The data processing terminal displays the calculated temperature gradients of each interval on the interface in the form of bar charts or line graphs, allowing operators to intuitively compare the insulation strength of each layer and interval.

[0056] S40. Heat Flux Density Calculation. The data processing terminal calculates the local heat flux density through each insulation layer according to Fourier's law of thermal conductivity. For any target analysis segment consisting of one or more measurement point intervals, the formula for calculating its average heat flux density q is: q = -k eff ·(ΔT / Δx), where k eff The effective thermal conductivity of the insulation material within the analysis section, i.e., the polyurethane layer or plywood, at the corresponding average temperature is given by ΔT, where ΔT is the temperature difference between the two ends of the analysis section, and Δx is the thickness of the analysis section. A positive value of the heat flux density q indicates that the heat conduction direction is from the external environment to the liquid storage space. Specifically, for the secondary insulation layer, the second bottom sensor T in the second temperature sensor can be used. 2a Second top sensor T 2c Using the temperatures at both ends of this layer as a reference, and combining the equivalent thermal conductivity of the plywood and polyurethane layers within the secondary insulation layer, the average heat flux density q2 of the secondary insulation layer is calculated. Similarly, for the primary insulation layer, the third bottom sensor T in the third temperature sensor is used. 3a and the third top sensor T 3c The average heat flux density q3 of the main insulation layer 4 is calculated. For other analysis sections, such as the area between the cabin plate and the bottom of the secondary insulation layer, and the area near the main shielding layer, similar calculations can be performed by selecting temperature sensor data from both ends of the corresponding section.

[0057] The data processing terminal displays the calculated heat flux density values ​​for each layer and section simultaneously with historical data on the interface, and shows the trajectory of heat flux density changes over time in the form of trend curves, allowing operators to perform long-term performance tracking and analysis.

[0058] S50. Insulation Layer Performance Evaluation. Based on the heat flux density and temperature difference data of each layer obtained in step S40, the data processing terminal further calculates the equivalent thermal resistance value R=ΔT / (q·A) of each functional layer, where A is the unit area or the actual heat transfer area corresponding to each monitoring chain. The larger the equivalent thermal resistance value R, the better the insulation performance of the layer and the stronger its ability to impede heat transfer.

[0059] Furthermore, the data processing terminal will use the equivalent thermal resistance R calculated by each functional layer. current The design reference thermal resistance R of this functional layer ref Perform a layer-by-layer comparison. Design a baseline thermal resistance value R. ref The initial reference thermal resistance values ​​of each layer are automatically recorded and stored by the system after the storage device has been newly built, pre-cooled and calibrated, and the insulation structure is confirmed to be intact. These values ​​are either theoretically calculated based on the nominal thermal conductivity and design thickness of the insulation material.

[0060] The evaluation logic for layer-by-layer comparison is as follows:

[0061] If the current thermal resistance value R of a certain functional layer current Compared with the design reference value R of this layer ref The ratio R current / R ref If the value is ≥0.85, meaning the attenuation is no more than 15%, the insulation performance of the layer is considered normal, and the system interface will mark it in green.

[0062] If 0.70≤R current / R ref If the value is less than 0.85, meaning the attenuation is between 15% and 30%, the insulation performance of the layer is judged to be slightly degraded. The system interface will mark it in yellow and give a warning, and it is recommended that operators increase the frequency of observation.

[0063] If R current / R ref If the value is less than 0.70, meaning the attenuation exceeds 30%, the insulation performance of the layer is considered severely degraded, and the system interface will mark it in red and trigger an alarm.

[0064] S60. Insulation Defect Identification and Layer-by-Layer Diagnosis. When one or more layers are determined to have degraded or severely deteriorated performance in the layer-by-layer evaluation results of step S50, the data processing terminal automatically initiates the insulation defect identification and layer-by-layer diagnosis process. The first basis for layer-by-layer diagnosis is the direct layer where the anomaly occurs. For example, if the abnormal change in temperature gradient is concentrated in the corresponding range of the main insulation layer, that is, the temperature difference between the third temperature sensors is significantly reduced, indicating an abnormal increase in the heat flux density through the main insulation layer, then the system determines that the main insulation layer has deteriorated insulation performance, possibly due to local compression, moisture absorption, icing, or chemical aging of the polyurethane foam insulation core layer.

[0065] The second basis for layer-by-layer diagnosis is the abrupt change in the temperature gradient between adjacent temperature measurement points. If there is a step-like abrupt change in the temperature gradient between adjacent temperature sensor pairs, that is, the temperature difference within that thin layer is far beyond the normal temperature difference range of adjacent sections, it indicates that there may be a localized direct leakage of cold energy caused by membrane perforation, cracks, or sealing failure at that location, rather than an overall degradation of the insulation material performance.

[0066] The third basis for layer-by-layer diagnosis is multi-section cross-comparison. The system performs lateral cross-comparison of the insulation performance data of the same layer from different monitoring chains on the same storage tank. If a certain functional layer in all sections shows a consistent performance degradation trend, it indicates a global aging problem of the insulation material in that layer; if only a certain layer in a few sections is abnormal while the same layer in other sections is normal, it indicates a local defect in the vicinity of that section.

[0067] After completing the stratum diagnosis, the data processing terminal automatically generates an insulation defect diagnosis report. This report includes the following: the timestamp of the anomaly, the stratum where the anomaly occurred, quantitative indicators of the anomaly severity, historical trend graphs of abnormal temperature gradient and heat flux density changes, qualitative analysis of possible causes, and recommended maintenance or further detection measures. This diagnostic report can be viewed directly on the display and alarm terminal, or exported in a standardized format for use by classification societies for inspection or by the facility operator for maintenance decisions.

[0068] S70. Long-term trend analysis and early warning. The data processing terminal continuously accumulates long-term historical records of temperature data from each monitoring chain, performs linear or exponential regression trend fitting on the change trajectory of the equivalent thermal resistance value of each layer over time, and predicts the degradation rate of the insulation performance of each functional layer and the estimated time to reach the next performance degradation threshold level. When the prediction results indicate that the thermal resistance value of a certain layer will drop to the severe degradation threshold within a preset time period in the future, the system automatically issues a forward-looking early warning, allowing the operator sufficient preparation time to arrange maintenance plans in advance.

[0069] This invention can also be applied to other cryogenic containers employing multi-layered insulation structures, such as membrane-type inner tanks of large-scale onshore full-containment LNG cryogenic storage tanks, liquid hydrogen storage tanks, liquid nitrogen storage tanks, liquid oxygen storage tanks, and liquefied carbon dioxide storage tanks. When applied to different cryogenic media, the purpose of this invention can be achieved simply by adjusting the sensor range and accuracy class according to the rated storage temperature of the medium, and by adjusting the spacing of the monitoring chain according to the geometric specifications of the storage tank.

[0070] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A cold-keeping monitoring system for a thin-film storage device, characterized in that: The storage device consists of, from the outside to the inside, a body plate, a secondary insulating layer, a secondary shielding layer, a primary insulating layer, a primary shielding layer, and a storage space. The secondary insulating layer is fixed to the inside of the body plate. The secondary shielding layer covers the upper surface of the secondary insulating layer. The primary insulating layer is laid on top of the secondary shielding layer. The primary shielding layer covers the upper surface of the primary insulating layer. The cold preservation monitoring system includes multiple monitoring chains, and each monitoring chain includes: An ambient temperature sensor is installed outside the cabin panel to collect a reference value of the atmospheric ambient temperature outside the storage device. A first temperature sensor is embedded in the cabin panel to collect the temperature of the cabin panel; A first temperature measuring group, the first temperature measuring group includes at least one second temperature sensor, the second temperature sensor being embedded in the secondary insulating layer; The second temperature measuring group includes at least one third temperature sensor, which is embedded in the main insulating layer. A liquid cargo temperature sensor is installed inside the storage space to collect the temperature of the liquid cargo inside the storage space. The first temperature sensor, the first temperature measuring group, and the second temperature measuring group are located in a cylindrical space with a straight line perpendicular to the plane of the cabin plate as the axis. The cold storage monitoring system also includes a temperature monitoring unit, wherein the ambient temperature sensor, the first temperature sensor, the first temperature measuring group, the second temperature measuring group, and the liquid cargo temperature sensor are respectively connected to the temperature monitoring unit via signal lines.

2. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, Multiple monitoring chains share one ambient temperature sensor and one liquid cargo temperature sensor. In each monitoring chain, there is one first temperature sensor, and the first temperature measurement group and the second temperature measurement group are respectively equipped with at least one second temperature sensor and at least one third temperature sensor.

3. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, Both the secondary insulation layer and the primary insulation layer are composed of multiple insulation blocks spliced ​​together, and the first temperature measuring group and the second temperature measuring group are located in the splicing gap between adjacent insulation blocks.

4. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The second temperature sensor and the third temperature sensor are each provided with at least three.

5. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The wiring harness of the second temperature sensor extends outward from the corresponding mounting position of the first temperature sensor.

6. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The secondary shielding layer is corrugated, and the corrugations protrude toward the secondary insulating layer. The wiring harness of the third temperature sensor is arranged in the accommodating gap between the main shielding layer and the secondary shielding layer. After the wiring harnesses of multiple second temperature measuring groups are gathered together, they are all led out from one exit position of the secondary shielding layer and the cabin plate.

7. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The liquid cargo temperature sensor, the first temperature sensor, the first temperature measuring group, and the second temperature measuring group are all equipped with vacuum-sealed joints at the through-hole positions between the main shielding layer, the secondary shielding layer, and the cabin plate.

8. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The cold storage monitoring system is located at least in a corner of the storage device.

9. The cold storage monitoring system for a thin-film storage device as described in claim 1, characterized in that, The cold storage monitoring system is located on top of the storage device.

10. A method for monitoring the cold preservation of a thin-film storage device, characterized in that, Includes the following steps: S10: Centralized acquisition and preprocessing of temperature data: All temperature signals are acquired synchronously at a preset frequency, and after analog-to-digital conversion and digital filtering, they are stored in the local database and synchronously transmitted to the data processing terminal. S20: Real-time temperature data display: Displays the real-time temperature values ​​of each measuring point on the industrial display screen interface of the display and alarm terminal in real time; S30: Temperature distribution curve and temperature gradient calculation: Draw the temperature distribution map of each temperature measuring point and calculate the temperature gradient between each two adjacent measuring points; S40: Heat flux density calculation: Calculate the local heat flux density through each insulation layer according to Fourier's law of thermal conductivity; S50: Insulation layer performance evaluation: Based on the heat flux density and temperature difference data of each layer obtained in step S40, the equivalent thermal resistance value of each functional layer is further calculated. The equivalent thermal resistance value is compared with the design reference thermal resistance value of the functional layer layer by layer to evaluate the insulation performance. S60: Identification and diagnosis of insulation defects: Identification and diagnosis of insulation defects are performed based on the results of the layer-by-layer evaluation in step S50. S70: Long-term trend analysis and early warning: Establish temperature databases for each monitoring chain, perform linear or exponential regression trend fitting on the change trajectory of equivalent thermal resistance values ​​of each layer over time, predict the degradation rate of insulation performance of each functional layer and the expected time to reach the next performance degradation threshold level, and issue early warnings.

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