LNG storage tank

Abstract

The utility model provides an LNG (Liquefied Natural Gas) storage tank, which relates to the technical field of LNG storage, and comprises a tank body with a cavity and a heat conducting piece, and the heat conducting piece is arranged in the cavity so as to passively and automatically conduct heat of a high-temperature layer in the cavity to a low-temperature layer. The problems that extra heat is introduced to LNG in a storage tank and the effect of a heat insulation system is affected due to intervention of a stirring system in the prior art are solved, the stirring system is complex in structure, and the system is efficient, reliable, free of moving parts and energy loss and low in cost. The problem that LNG in the storage tank rolls over is thoroughly solved, the problems that equipment is inevitable to age and difficult to maintain due to the fact that the stirring system is in a starting state for a long time or in the repeated starting and stopping process are solved, in addition, the LNG in the storage tank operated and maintained through the system is more stable, the quality of the LNG is easier to maintain, and aging is reduced.

Description

Technical Field

[0001] The utility model relates to the field of LNG storage, in particular to an LNG storage tank. Background Art

[0002] During the transportation and storage of LNG (liquefied natural gas), although efficient insulation measures are adopted, heat transfer still exists due to the large temperature difference between LNG and the external environment. As the LNG is retained in the tank and the temperature of the tank wall changes, the LNG on the upper surface continues to absorb heat and evaporates, and the temperature remains unchanged, while the LNG in the lower part continues to absorb heat and the temperature rises, resulting in stratification of the LNG temperature and density distribution in the tank. When the LNG with higher density is at the bottom and the LNG with lower density is at the top, the LNG in the tank is in a stable or balanced state, but when the temperature difference causes the density stratification to reverse, that is, the density of the upper layer or the upper part is greater than the density of the lower layer or the lower part, the upper and lower layers of LNG roll over. At the same time, because the LNG with lower density or higher temperature in the lower layer rolls over to the upper layer, its pressure decreases rapidly, which in turn causes the rapid gasification of LNG and the rapid increase of the pressure in the tank. In severe cases, the tank may be damaged.

[0003] In the prior art, there is an anti-stratification device for LNG storage tanks disclosed in announcement number CN203202590U, for example, which utilizes a stirring system to continuously stir the LNG to maintain a uniform temperature distribution in the tank.

[0004] However, in the above structure, the involvement of the mixing system brings new heat to the LNG, which greatly reduces the effect of the original insulation measures;

[0005] On the other hand, the mixing system has a complex structure and long-term mixing will inevitably lead to equipment aging, making it unsuitable for industrial use. Utility Model Content

[0006] In view of the deficiencies in the prior art, the utility model provides an LNG storage tank, which solves the problem that the intervention of the stirring system in the prior art brings additional heat to the LNG, resulting in a reduction in the effectiveness of the original insulation measures, and the stirring system has a complex structure. Long-term stirring start-up state or repeated start-stop cycles inevitably lead to equipment aging and are not suitable for practical applications.

[0007] At least one embodiment of the utility model provides an LNG storage tank, comprising: a tank body having a chamber, and a heat conducting member, wherein:

[0008] The heat conducting member is arranged in the chamber to passively and automatically conduct the heat from the high temperature layer in the chamber to the low temperature layer.

[0009] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0010] The use of heat conducting parts can effectively complete heat conduction in the storage tank without energy input or no energy consumption, thereby keeping the LNG in the storage tank vertically consistent along the heat conducting parts in the height difference dimension, thereby maintaining the density of LNG from being inverted "heavy on top and light on the bottom", avoiding the tumbling of the upper and lower layers of LNG, and avoiding the rapid reduction in pressure when the higher temperature lower LNG rises due to the tumbling process, thereby causing the risk of rapid gasification and rapid increase in pressure in the storage tank;

[0011] The heat is transferred automatically and passively by heat-conducting parts. It has a simple structure, no moving parts, and no energy consumption. It can avoid the impact of equipment aging to the greatest extent and will not bring new heat sources to the LNG in the tank, making it more suitable for practical applications.

[0012] In an LNG storage tank provided by at least one embodiment of the present utility model, the heat conducting member comprises a solid heat conducting rod, and the solid heat conducting rod is vertically arranged in the chamber.

[0013] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0014] By using a solid heat conductive rod, the heat of the LNG in the lower high-temperature layer can be transferred vertically upward along the rod to the LNG in the upper low-temperature layer, thereby passively maintaining the temperature of the LNG at different heights in the tank to be consistent without the need for energy input.

[0015] In an LNG storage tank provided by at least one embodiment of the utility model, the solid heat conductive rod is a solid copper rod.

[0016] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0017] The excellent thermal conductivity of copper rods can provide long-term and reliable heat conduction in LNG storage tanks.

[0018] In an LNG storage tank provided by at least one embodiment of the present invention, the heat conducting member comprises a hollow heat conducting rod, which is vertically arranged in the chamber, and both ends of the hollow heat conducting rod remain open.

[0019] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0020] By utilizing the hollow heat-conducting rod and the openings at both ends of the hollow heat-conducting rod, on the one hand, convection between the upper layer of liquefied natural gas and the lower layer of liquefied natural gas in the LNG storage tank can be achieved to maintain a uniform distribution of the liquefied natural gas in the LNG storage tank. At the same time, the hollow heat-conducting rod itself can also transfer heat between the upper layer of liquefied natural gas and the lower layer of liquefied natural gas, thereby generally making the temperature of the liquefied natural gas in the LNG storage tank tend to be consistent.

[0021] In an LNG storage tank provided by at least one embodiment of the utility model, a plurality of through holes communicating with the inside and the outside are provided on the ring side surface of the hollow heat conducting rod.

[0022] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0023] By utilizing the plurality of through holes, the flow of liquefied natural gas inside and outside the hollow heat conducting rod can be further realized.

[0024] In an LNG storage tank provided in at least one embodiment of the present utility model, the tank body includes a main body and a tank top for closing the main body:

[0025] There are a plurality of heat-conducting members, and each of the heat-conducting members is evenly suspended on the tank top.

[0026] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0027] By hanging it on the top of the tank, it can avoid the external heat from being transferred to LNG through the heat conducting parts as much as possible. At the same time, by using multiple heat conducting parts evenly distributed in the tank body, the temperature of LNG in the storage tank can be maintained more effectively and quickly.

[0028] In an LNG storage tank provided by at least one embodiment of the present utility model, the heat-conducting member includes a heat-conducting film or a heat-conducting plate, and the heat-conducting film or the heat-conducting plate is evenly distributed in the tank body.

[0029] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0030] By using the thermal conductive film, the heat of the LNG with a higher temperature in the lower layer can be automatically transferred to the LNG with a lower temperature in the upper layer along the surface of the thermal conductive film, so as to maintain a uniform temperature distribution of the LNG in the storage tank and eliminate the phenomenon of LNG rolling.

[0031] In an LNG storage tank provided by at least one embodiment of the present utility model, a driving impeller rotatable by a power member is further disposed in the tank body, and the driving impeller is configured to rotate in a horizontal direction.

[0032] In at least one embodiment of the present invention, an LNG storage tank is provided, which also includes a temperature monitoring system and a data processing system, wherein:

[0033] The temperature monitoring system is arranged at different heights in the tank body, the data processing system is arranged on the tank body and is communicatively connected with the temperature monitoring system, and the data processing system is also communicatively connected with the power component.

[0034] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0035] By utilizing the data processing system and the temperature monitoring system, in special circumstances, such as when the storage tank is abnormally damaged, resulting in a large temperature difference between the upper and lower layers of LNG, and the heat conductor is unable to transfer the heat of the lower layer of LNG to the upper layer of LNG in a timely manner, the temperature difference information of the upper and lower layers of LNG can be collected under the monitoring of the temperature monitoring system, and the temperature difference information can be transmitted to the data processing system to determine and control the rotation of the driving impeller so that the LNG in the storage tank forms appropriate convection in the vertical direction, so as to maintain the temperature of the LNG at different heights in the storage tank to be consistent, and to avoid the LNG in the storage tank from rolling over due to the large temperature difference.

[0036] In an LNG storage tank provided by at least one embodiment of the present invention, the driving impeller is arranged at the bottom of the chamber, and the power component includes a motor installed on the top of the tank body. The motor is connected to the driving impeller through a connecting rod to drive the driving impeller to rotate.

[0037] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0038] The motor can be used to control the rotation of the driving impeller, thereby stirring the LNG in the storage tank, so that the LNG in the storage tank forms appropriate convection in the vertical direction to maintain the LNG temperature at different heights in the storage tank to be consistent.

[0039] In an LNG storage tank provided by at least one embodiment of the utility model, an LNG export system is provided at the bottom of the tank chamber, and an LNG injection system is provided at the top.

[0040] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0041] Maintaining one-way liquefied natural gas injection and liquefied natural gas output can better maintain the stability of liquefied natural gas in the LNG storage tank and improve the quality preservation effect of liquefied natural gas.

[0042] At least one embodiment of the present utility model further provides a method for eliminating the risk of LNG rolling and pressure management in the tank, which is applied to the above-mentioned LNG storage tank, comprising:

[0043] The heat transfer is automatically carried out vertically by heat conducting parts, so as to passively maintain the temperature of LNG in the tank at different heights to be consistent.

[0044] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0045] The use of heat conducting parts can achieve effective and automatic heat conduction in the storage tank without energy input or no energy consumption, thereby keeping the LNG in the storage tank consistent along the heat conducting parts and the surrounding vertical direction in the height difference dimension, thereby avoiding the LNG in the upper and lower layers from rolling over, and avoiding the rapid reduction of pressure caused by the rapid movement of the LNG in the lower layer to the upper layer due to the rolling, thereby causing the risk of rapid gasification of LNG and rapid increase of pressure in the storage tank;

[0046] The heat is transferred passively by heat conducting parts, which has a simple structure, can avoid the influence of equipment aging as much as possible, and will not bring new heat sources to the LNG in the tank, making it more industrially applicable.

[0047] In at least one embodiment of the present utility model, a method for eliminating the risk of LNG rolling and pressure management in a tank is provided, which also includes:

[0048] The temperature monitoring system obtains a plurality of temperature information corresponding to different heights in the storage tank, and transmits each of the temperature information to the data processing system;

[0049] The data processing system controls the power component to operate according to each of the temperature information, so as to drive the driving impeller to rotate, when the temperature difference between the maximum temperature and the minimum temperature is greater than a preset threshold, until the temperature difference is lower than the preset threshold.

[0050] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0051] By using the data processing system and the temperature monitoring system, in special circumstances, such as abnormal damage to the storage tank, resulting in a large temperature difference between the upper and lower LNG layers, and the heat transfer element cannot transfer the heat of the lower LNG layer to the upper LNG layer in time, the temperature difference between the upper and lower LNG layers can be collected under the monitoring of the temperature monitoring system, and the temperature difference can be transferred to the data processing system to determine and control the rotation of the driving impeller, so that the LNG in the storage tank forms appropriate convection in the vertical direction, so as to maintain the temperature of the LNG at different heights in the storage tank to be consistent, and avoid the LNG in the storage tank from rolling due to the large temperature difference. In addition, the temperature monitoring system can also issue an early warning in the case of a large temperature difference between layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The utility model is a simplified structural schematic diagram of an LNG storage tank.

[0053] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0054] 1. Tank body, 2. Heat transfer parts, 3. Lower layer liquefied natural gas, 4. Upper layer liquefied natural gas, 5. BOG. DETAILED DESCRIPTION

[0055] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0056] Furthermore, those skilled in the art may combine and associate different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0057] Under the condition that it is difficult to install or no natural gas pipeline has been installed, the transportation of LNG (Liquid Natural Gas, LNG) is the most efficient form of natural gas storage and transportation, and it is also one of the main forms of natural gas import, transportation and storage in my country.

[0058] In the LNG industry chain, whether it is base load, peak load, terminal or secondary terminal, LNG is usually stored in dedicated tank containers after being unloaded by LNG carriers at the station. Obviously, LNG transportation and storage are very critical links. Usually, these facilities maintain LNG at -163℃ and 0.1MPa.

[0059] During the transportation and storage of LNG, although efficient insulation measures are adopted, heat transfer still occurs due to the large temperature difference between LNG and the external environment. After the heat enters the LNG storage tank, it eventually causes the LNG on its upper surface to absorb heat and evaporate, while keeping the temperature of the LNG on the upper surface always at a low temperature and unchanged state. However, due to the high pressure, the temperature of the LNG at the lower part or bottom will accumulate and rise without evaporating, causing the temperature of the lower part to be higher than the temperature of the LNG at the upper part or on the upper surface, which eventually causes the density of LNG to be inverted. Due to the differences in liquid density and temperature of the LNG at different heights in the storage tank, the so-called LNG above will experience temperature and density stratification in the case of less disturbance. The above heat exchange process may cause the temperature or density distribution of the LNG liquid inside the storage tank to change as time accumulates or is affected by the LNG filling and external transmission methods. When the critical point of density inversion is reached, the LNG will "roll over" up and down, disrupting the existing stratification. In severe cases, the LNG will be rapidly vaporized, and the large amount of steam (BOG5, Boil-off Gas) generated quickly will cause the pressure inside the storage tank to rise sharply, impacting the structural integrity of the storage tank, and causing the safety risk of the storage tank system failure or explosion. It is necessary to understand the mechanism of the above LNG safety risks and take scientific countermeasures to solve the LNG rolling problem in the storage tank.

[0060] During the transportation and storage of LNG, although efficient insulation measures are adopted, heat transfer still exists due to the large temperature difference between LNG and the external environment. Due to the differences in liquid density and temperature at different heights in the LNG storage tank, LNG stratification occurs under small disturbance conditions. The above heat exchange process may cause the temperature or density distribution of the LNG liquid inside the storage tank to change over time or be affected by the LNG filling and external transmission methods, resulting in a "rollover" phenomenon, which disrupts the existing stratification. In severe cases, it will impact the structural integrity of the storage tank and the rapid gasification of LNG, generate a large amount of steam (BOG5, Boil-off Gas) and cause the pressure in the storage tank to rise sharply, causing the safety risk of tank system failure or explosion. It is necessary to understand the mechanism of the above-mentioned LNG safety risks and take scientific countermeasures to solve the problem of LNG rollover in the storage tank.

[0061] Although the global economy has begun to shift from fossil energy structure to renewable energy, natural gas is also used as chemical raw materials in many countries, and its share in planning is still increasing. With the improvement of environmental protection requirements, LNG, as a cleaner choice among fossil fuels and its wide availability, will be more widely used in the future; at the same time, with the continuous advancement of technology and the reduction of costs, the continuous expansion of application areas, the production, storage and transportation of LNG will be safer and more efficient, and its market demand will continue to grow.

[0062] Research and engineering practice show that it is still a major challenge for the industry to effectively manage the tumbling and associated BOG5 generation during LNG storage and transportation. The rapid generation of LNG vapor can lead to a sharp increase in pressure in the tank and damage to the tank. Chen et al. (2004, 10) pointed out that the evaporation rate of ordinary large LNG tanks is about 0.03-0.08vol% / day, causing serious energy waste and even safety accidents. Therefore, the aging of LNG and the exploration of methods for treating BOG5 have become research hotspots for scientific researchers in recent years.

[0063] There are a large number of simulation and experimental studies on the evaporation model and heat transfer characteristics of LNG in storage tanks at home and abroad. Pellegrini et al. (2014.02) studied the influence of environmental conditions on LNG aging through experiments and established a time-varying evaporation model of LNG in storage tanks. The model was further improved by Migliore et al. (2015.09) in subsequent studies, and its output results can provide an approximate value of the evaporation rate after temperature changes. Wordu et al. (2013.01) established a heat transfer model for LNG through unloading pumps, unloading pipelines, and recirculation pipelines. The model explicitly considers the heat exchange of each entity in the LNG receiving station. However, the model is completely theoretical, in which the heat entering the evaporation system and the generation of evaporation gas are directly calculated based on empirical correlations. Roh et al. (2012.11) studied the convective heat transfer problem between the storage tank and the external environment and found that the heat flow provided by the gas phase to the liquid phase is negligible compared with the heat flow from the liquid phase to the gas phase, and the evaporation rate depends largely on the contact area of ​​the solid-liquid interface, but has nothing to do with the size of the contact area of ​​the gas-liquid interface. Li Yuxing et al. (2010.05) studied the relationship between the pressure inside the tank, daily evaporation and evaporation rate based on the natural pressure rise method. The results showed that when the initial filling rate of the tank is less than the critical filling rate, the daily evaporation and evaporation rate will increase with time. Conversely, the daily evaporation and evaporation rate will increase first and then decrease with time. Chen Ruiying et al. (2020.07) studied the influence of ambient temperature and solar radiation on the evaporation rate of LNG when the tank is stationary based on ANSYS software, and used laminar model and turbulent model for CFD calculation respectively. The results showed that the laminar model is closer to the actual situation.

[0064] In addition, two stratified LNG with different densities in the same tank suddenly roll and mix, and reach equilibrium due to the entry of surrounding heat, which causes the high-temperature LNG at the bottom to suddenly begin to evaporate when it reaches the surface. Tumbling will produce a large amount of BOG5 (about 160 times the output mode) and rapidly increase the internal pressure of the tank, which is a unique and dangerous phenomenon in the LNG industry. Therefore, it is crucial to understand and predict the operating behavior of LNG tanks through basic research. In 1965, the Turner model was proposed. This model gave the heat and mass transfer relationship by considering salt solutions with different concentrations and temperatures. It was regarded as a reference for LNG theoretical modeling methods, but the criterion did not match the data in the actual La Spezia incident. Wang et al. (2008.09) studied the convection phenomenon in the LNG stratification process and used the double diffusion convection model to simulate and predict the mixed flow. Li et al. (2015.09) introduced the rollover coefficient to quantify the rollover strength of the tank under different LNG densities and tank sizes. The results showed that the rollover coefficient initially increased within a small range and then increased rapidly with the increase of the initial density difference. Hubert et al. (2019.11) considered the inflow of gas phase and heat in the model on the basis of the above, developed a new solver to simulate the rolling phenomenon, and further studied the rolling behavior of the tank and the generation of BOG5. Zhen Yangyang et al. (2020.01) used the CFD method to study the entropy generation of the LNG stratified rolling process of ships under different motion states, and conducted a qualitative analysis of the energy and momentum in the LNG stratified rolling process. The results showed that the liquid flow entropy generation rate showed a periodic change, and the flow entropy generation rate increased with the increase of the ship motion amplitude and decreased with the increase of the ship motion cycle; the heat transfer entropy generation value decreased with the increase of the motion amplitude and decreased with the decrease of the motion cycle. Wu Song et al. (2022.01) studied the relationship between the rolling phenomenon of tanks with different tank capacities and the critical density difference, and found that the LNG rolling velocity increased with the increase of the initial density difference of the stratification, and the initial density difference was the direct cause of the LNG rolling.

[0065] In summary, the research on LNG stratification, tumbling and gasification during transportation or storage has been quite in-depth, but there are still some shortcomings:

[0066] 1. No effective method for suppressing the rolling phenomenon is proposed;

[0067] 2. The research is too academic, theoretical, and idealistic, deviating from the research goal of solving the safety problem of LNG storage tank operation and maintenance;

[0068] 3. In the study of heat exchange between storage tanks and the external environment, the simulation conditions are generally ideal, but the LNG transportation process is a dynamic process, and it is necessary to take the gas phase in the tank into account and study the impact of the solid-liquid interface changes on heat exchange under the dynamic effect in depth;

[0069] 4. Although a variety of BOG5 reliquefaction response strategies have been proposed, most of the strategies are studied on large LNG carriers. Whether the process is applicable to small LNG carriers with narrow space still needs to be considered. Therefore, the universal applicability of hull parameters should be considered in the design project.

[0070] In order to effectively suppress the tumbling of LNG in the storage tank and make it more suitable for actual industrial applications, the utility model provides an LNG storage tank.

[0071] Embodiment 1:

[0072] The LNG storage tank comprises: a tank body 1 having a chamber, and a heat conducting member 2, wherein:

[0073] The heat conductor 2 is arranged in the chamber to passively and automatically conduct the heat from the high-temperature layer in the chamber to the low-temperature layer in a passive heat conduction manner. It should be understood that in the LNG storage tank, the low-temperature layer refers to the upper layer of liquefied natural gas 4, and the high-temperature layer refers to the lower layer of liquefied natural gas 3. The specific structure of the tank body 1 and the implementation method of sealing and insulation are existing technologies, and the utility model will not be repeated here.

[0074] By using the heat conducting member 2, heat conduction can be effectively completed in the storage tank without energy input or without energy consumption, thereby keeping the LNG in the storage tank vertically consistent along the heat conducting member 2 in the height difference dimension, thereby avoiding the tumbling of the upper and lower layers of LNG, and avoiding the rapid reduction of LNG pressure due to tumbling, thereby causing the risk of rapid gasification and rapid increase of pressure in the storage tank;

[0075] The heat transfer is performed passively by the heat conducting member 2, which has a simple structure, can avoid the influence of equipment aging as much as possible, and will not bring a new heat source to the LNG in the tank, and is more industrially applicable.

[0076] Specifically, the heat conducting member 2 includes a solid heat conducting rod, such as a solid heat conducting copper rod. Of course, the heat conducting rod can also be made of other materials with heat conducting properties, which is not limited here. The solid heat conducting rod is vertically arranged in the chamber.

[0077] By using a solid heat conductive rod, the heat of the LNG in the lower layer with a higher temperature can be transferred vertically upward along the rod to the LNG in the upper layer, thereby passively maintaining the temperature of the LNG at different heights in the tank to be consistent without the need for energy input.

[0078] Preferably, the tank body 1 comprises a main body and a tank top for closing the main body:

[0079] The heat conducting member 2 in this embodiment is a solid heat conducting copper rod, and there are multiple solid heat conducting copper rods, each of which is evenly suspended on the top of the tank.

[0080] By hanging it on the tank top, it is possible to avoid external heat from being transferred to LNG through the heat conducting member 2. At the same time, by evenly distributing multiple heat conducting members 2 in the tank body 1, the temperature of LNG in the storage tank can be maintained more effectively and quickly.

[0081] Embodiment 2:

[0082] The difference between this embodiment and embodiment 1 is that the heat conducting member 2 used in this embodiment is a hollow heat conducting rod, which is vertically arranged in the chamber, and both ends of the hollow heat conducting rod remain open and / or the ring side of the hollow heat conducting rod is provided with a plurality of through holes connecting the inside and the outside, so that the liquefied natural gas inside and outside the hollow heat conducting rod can flow automatically.

[0083] By utilizing the hollow heat-conducting rod and the openings or through holes at both ends and / or on the side surfaces of the hollow heat-conducting rod, on the one hand, convection between the upper layer of liquefied natural gas and the lower layer of liquefied natural gas in the LNG storage tank can be achieved, thereby maintaining a uniform distribution of the liquefied natural gas in the LNG storage tank. At the same time, the hollow heat-conducting rod itself can also transfer heat between the upper layer of liquefied natural gas and the lower layer of liquefied natural gas, thereby generally making the temperature of the liquefied natural gas in the LNG storage tank tend to be consistent.

[0084] Preferably, the tank body 1 comprises a main body and a tank top for closing the main body:

[0085] The heat conducting member 2 is a hollow heat conducting rod in this embodiment, and there are multiple hollow heat conducting rods, each of which is evenly suspended on the top of the tank.

[0086] By hanging it on the tank top, it is possible to avoid external heat from being transferred to LNG through the heat conducting member 2. At the same time, by evenly distributing multiple heat conducting members 2 in the tank body 1, the temperature of LNG in the storage tank can be maintained more effectively and quickly.

[0087] Embodiment 3:

[0088] The difference between this embodiment and embodiment 1 is that the heat conducting member 2 used in this embodiment is a heat conducting film or a heat conducting plate, and the heat conducting film or the heat conducting plate is evenly distributed in the tank body 1 .

[0089] By using a heat-conducting film or a heat-conducting plate, the heat of the LNG in the lower layer with a higher temperature can be automatically transferred to the LNG in the upper layer with a lower temperature along the surface of the heat-conducting film, so as to maintain a uniform temperature distribution of the LNG in the storage tank and eliminate the phenomenon of LNG tumbling.

[0090] Embodiment 4:

[0091] The difference between this embodiment and embodiment 1 is that a driving impeller which can rotate under the drive of a power member is further arranged in the tank body 1, and the driving impeller is arranged to rotate in a horizontal direction, that is, the rotation axis of the driving impeller is horizontal, and its blades rotate and move up and down in a vertical direction. The storage tank also includes a temperature monitoring system and a data processing system, wherein:

[0092] The temperature monitoring system is arranged at different heights in the tank body 1 , the data processing system is arranged on the tank body 1 and is communicatively connected with the temperature monitoring system, and the data processing system is also communicatively connected with the power component.

[0093] It should be understood that the working principles of the temperature monitoring system and the data processing system, as well as the process of monitoring temperature and transmitting information are all existing technologies and will not be elaborated here.

[0094] By utilizing the data processing system and the temperature monitoring system, in special circumstances, such as when the storage tank is abnormally damaged, resulting in a large temperature difference between the upper and lower layers of LNG, and the heat conductor 2 is unable to transfer the heat of the lower layer of LNG to the upper layer of LNG in a timely manner, the temperature difference between the upper and lower layers of LNG can be collected under the monitoring of the temperature monitoring system, and the temperature difference can be transmitted to the data processing system to determine and control the rotation of the driving impeller so that the LNG in the storage tank forms appropriate convection in the vertical direction, so as to maintain the temperature of the LNG at different heights in the storage tank to be consistent, and to avoid the LNG in the storage tank from rolling over due to the large temperature difference.

[0095] Specifically, the driving impeller is arranged at the bottom of the chamber, and the power part includes a motor installed on the top of the tank body 1, and the motor is connected to the driving impeller through a connecting rod to drive the driving impeller to rotate.

[0096] The motor can be used to control the rotation of the driving impeller, thereby stirring the LNG in the storage tank, so that the LNG in the storage tank forms appropriate convection in the vertical direction to maintain the LNG temperature at different heights in the storage tank to be consistent.

[0097] More preferably, an LNG export system is provided at the bottom of the storage tank chamber, and an LNG injection system is provided at the top.

[0098] Maintaining one-way liquefied natural gas injection and liquefied natural gas output can better maintain the stability of liquefied natural gas in the LNG storage tank and improve the quality preservation effect of liquefied natural gas.

[0099] The utility model also provides a method for eliminating the risk of LNG rolling and pressure management in the tank, which is applied to the above-mentioned LNG storage tank, comprising:

[0100] The heat conducting member 2 is used to automatically transfer heat vertically, so as to passively maintain the temperature of the LNG in the tank body 1 to be consistent at different heights.

[0101] By using the heat conducting member 2, heat conduction can be effectively completed in the storage tank without energy input or without energy consumption, thereby keeping the LNG in the storage tank vertically consistent along the heat conducting member 2 in the height difference dimension, thereby avoiding the tumbling of the upper and lower layers of LNG, and avoiding the rapid reduction of LNG pressure due to tumbling, thereby causing the risk of rapid gasification and rapid increase of pressure in the storage tank;

[0102] The heat transfer is performed passively by the heat conducting member 2, which has a simple structure, can avoid the influence of equipment aging as much as possible, and will not bring new heat sources to the LNG in the tank, and is more industrially applicable.

[0103] Furthermore, the method further comprises:

[0104] The temperature monitoring system obtains multiple temperature information corresponding to different heights in the storage tank and transmits each temperature information to the data processing system;

[0105] The data processing system controls the power component to operate according to each temperature information to drive the impeller to rotate when the temperature difference between the maximum temperature and the minimum temperature is greater than a preset threshold value, until the temperature difference is lower than the preset threshold value.

[0106] By utilizing the data processing system and the temperature monitoring system, in special circumstances, such as when the storage tank is abnormally damaged, resulting in a large temperature difference between the upper and lower layers of LNG, and the heat conductor 2 is unable to transfer the heat of the lower layer of LNG to the upper layer of LNG in a timely manner, the temperature difference between the upper and lower layers of LNG can be collected under the monitoring of the temperature monitoring system, and the temperature difference can be transmitted to the data processing system to determine and control the rotation of the driving impeller so that the LNG in the storage tank forms appropriate convection in the vertical direction, so as to maintain the temperature of the LNG at different heights in the storage tank to be consistent, and to avoid the LNG in the storage tank from rolling over due to the large temperature difference.

[0107] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An LNG storage tank, characterized in that: include: A tank body (1) having a chamber, and a heat conducting member (2), wherein: The heat conducting element (2) is arranged in the chamber to passively and automatically conduct heat from the high-temperature layer in the chamber to the low-temperature layer.

2. The LNG storage tank according to claim 1, characterized in that: The heat conducting member (2) comprises a solid heat conducting rod, and the solid heat conducting rod is vertically arranged in the chamber.

3. An LNG storage tank according to claim 2, characterized in that: The solid heat conducting rod is a solid copper rod.

4. The LNG storage tank according to claim 1, characterized in that: The heat conducting member (2) comprises a hollow heat conducting rod, which is arranged vertically in the chamber, and both ends of the hollow heat conducting rod remain open.

5. The LNG storage tank according to claim 4, characterized in that: The ring side surface of the hollow heat conducting rod is provided with a plurality of through holes communicating with the inside and the outside.

6. An LNG storage tank according to any one of claims 2 to 5, characterized in that: The tank body (1) comprises a main body and a tank top for closing the main body: There are a plurality of heat-conducting members (2), and each of the heat-conducting members (2) is evenly suspended on the tank top.

7. The LNG storage tank according to claim 1, characterized in that: The heat-conducting element (2) comprises a heat-conducting film or a heat-conducting plate, and the heat-conducting film or the heat-conducting plate is evenly distributed vertically inside the tank body (1).

8. An LNG storage tank according to any one of claims 2, 3, 4 and 7, characterized in that: The tank body (1) is also provided with a driving impeller which can rotate under the drive of a power member, and the driving impeller is configured to rotate in a horizontal direction.

9. The LNG storage tank according to claim 8, characterized in that: It also includes a temperature monitoring system and a data processing system, wherein: The temperature monitoring system is arranged at different heights in the tank body (1), the data processing system is arranged on the tank body (1) and is communicatively connected to the temperature monitoring system, and the data processing system is also communicatively connected to the power component.

10. The LNG storage tank according to claim 1, characterized in that: The bottom of the tank body (1) is provided with an LNG export system, and the top of the tank body (1) is provided with an LNG injection system.

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