A LNG carrier liquid surface sloshing suppression device

Abstract

The application provides a LNG carrier liquid surface sloshing suppression device, in use, the LNG carrier liquid surface sloshing suppression device is placed in the liquid storage tank, the liquid contact surface of the air bag is in contact with the LNG liquid surface, and the air bag is submerged under the gravity of the counterweight plate, so that the liquid contact surface of the air bag is partially immersed in the LNG liquid.The main liquid surface fluctuation is transmitted to the liquid contact surface on the air bag when the LNG liquid in the liquid storage tank is caused to slosh due to factors such as waves and ship movement during the ship sailing.At this time, due to the different sizes of the volumes in the plurality of spoiler grooves, the inherent frequencies of the LNG liquids in the spoiler grooves are different, thereby generating multi-frequency local disturbances.These disturbances destroy the energy concentration of the main liquid surface dominant frequency through nonlinear interaction, and at the same time dissipate the sloshing power energy through turbulence, finally suppress the liquid sloshing amplitude, and avoid the formation of resonance conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LNG transportation, and in particular to a liquid surface sloshing suppression device for LNG transportation ship. BACKGROUND

[0002] Natural gas is gaseous at room temperature. In order to facilitate storage and transportation, it is usually cooled to extremely low temperature to change it into liquid state, i.e. liquefied natural gas (LNG). This process can reduce the volume of natural gas by about 600 times, greatly improving the storage and transportation efficiency.

[0003] With the increasing global demand for LNG, sea transportation has become an important way for LNG cross-regional delivery. LNG transportation ships are specially used for ocean transportation of liquefied natural gas. During the transportation process, LNG needs to be stored in special liquid storage tanks in the ship body. Since the thin film type liquid storage tank can better fit the ship body structure, thereby improving the space utilization, at present, most LNG transportation ships generally adopt such storage tanks.

[0004] However, such thin film liquid storage tank is usually large in size. In the case of partial filling of LNG (for example, loading is not full or unloading), the ship will sway due to external forces such as waves during sailing, and then the free surface sloshing of LNG liquid in the tank will occur (i.e. liquid sloshing phenomenon). Once the LNG in the liquid storage tank appears liquid sloshing resonance, it may pose a serious threat to the ship body structure and navigation safety. Liquid sloshing resonance is a kind of dynamics phenomenon that the natural sloshing frequency of liquid in the liquid storage tank is consistent or close to the frequency of external environment (such as waves, ship body movement), thereby causing the liquid sloshing amplitude to be sharply amplified.

[0005] Liquid sloshing resonance can cause: when LNG collides with the tank wall violently, a transient impact pressure of several hundred kPa can be generated. High frequency impact and repeated stress cycle aggravate the fatigue of tank wall weld, which may cause cracking. The back and forth sloshing of LNG can change the distribution of ship body gravity center, cause roll coupling pitch, affect the ship attitude control, and in severe cases, may cause difficult control and even capsizing risk. SUMMARY

[0006] Therefore, it is necessary to provide a liquid surface sloshing suppression device for LNG transportation ship to solve the above problems.

[0007] Embodiments of the present application provide a liquid surface sloshing suppression device for LNG transportation ship, comprising:

[0008] a counterweight plate;

[0009] an air bag, which is sleeved on the outer surface of the counterweight plate to isolate the counterweight plate and the liquid natural gas; the air bag is formed with a gas containing part on the side of the counterweight plate facing the LNG liquid surface, and a gas containing cavity is formed in the gas containing part;

[0010] The liquid contact surface of the gas containing portion in contact with the LNG liquid surface is formed with a plurality of turbulence grooves recessed toward the side of the counterweight plate, and the volumes of at least two of the turbulence grooves are different.

[0011] In at least one embodiment of the present application, the plurality of turbulence grooves are asymmetrically arranged on the liquid contact surface.

[0012] In at least one embodiment of the present application, the gas containing portion includes a protruding portion protruding away from the side of the counterweight plate, the protruding portion surrounds the outer periphery of the turbulence grooves, and the gas containing cavity is at least partially located in the protruding portion.

[0013] In at least one embodiment of the present application, a portion of the gas containing cavity is located between the turbulence grooves and the counterweight plate.

[0014] In at least one embodiment of the present application, the number of gas containing portions is a plurality, and any of the gas containing portions has an independent gas containing cavity and at least one turbulence groove.

[0015] In at least one embodiment of the present application, the plurality of gas containing portions are arranged in an asymmetric manner on the side of the counterweight plate facing the LNG liquid surface.

[0016] In at least one embodiment of the present application, at least the projected area of the gas containing portion on the counterweight plate is different.

[0017] In at least one embodiment of the present application, the LNG carrier liquid surface sloshing suppression device further comprises:

[0018] A gas pressure adjusting assembly connected to the gas containing portion, the gas pressure adjusting assembly being used to charge or exhaust gas to the gas containing portion to adjust the pressure in the gas containing portion; and

[0019] A gas sensor arranged in the gas containing portion for detecting the pressure in the gas containing portion.

[0020] In at least one embodiment of the present application, the counterweight plate comprises austenitic stainless steel.

[0021] In at least one embodiment of the present application, the LNG carrier liquid surface sloshing suppression device further comprises:

[0022] A lifting assembly, one end of which is mounted on the inner wall of the liquid tank containing LNG, and the other end of which is fixed to the air bag to allow the air bag to move relative to the inner wall of the liquid tank.

[0023] The LNG carrier liquid surface sloshing suppression device of the present embodiment has at least the following beneficial effects:

[0024] 1. The LNG carrier liquid surface sloshing suppression device provided above, in use, the LNG carrier liquid surface sloshing suppression device is placed in the liquid storage tank, the liquid contact surface of the air bag is in contact with the LNG liquid surface, and the air bag is submerged under the gravity of the counterweight plate, so that the liquid contact surface of the air bag is partially immersed in the LNG liquid.

[0025] When the LNG liquid in the liquid storage tank is shaken due to factors such as waves and ship movement during the ship sailing process, the main liquid surface fluctuation will be transmitted to the liquid contact surface on the air bag. At this time, due to the different sizes of the volumes in the multiple turbulence grooves, the natural frequencies of the LNG liquids in the grooves are different, thereby generating multiple-frequency local disturbances. These disturbances destroy the energy concentration of the main liquid surface dominant frequency through nonlinear interaction, and at the same time, the turbulence structure causes vortex and shear flow in the groove, resulting in enhanced local turbulence and viscous dissipation. Ultimately, the liquid sloshing amplitude is suppressed to avoid the formation of resonance conditions.

[0026] 2. The LNG carrier liquid surface sloshing suppression device provided above, the asymmetric turbulence layout is less dependent on the liquid surface height or a single wave direction, and is more adaptable to wave incidence direction and frequency. In complex and irregular sea conditions, the LNG carrier liquid surface sloshing suppression device can still maintain effective liquid sloshing suppression capability and improve the universality and practicality of the LNG carrier liquid surface sloshing suppression device.

[0027] 3. The LNG carrier liquid surface sloshing suppression device provided above, the asymmetric disturbance source can scatter the liquid free surface in the tank to form a regular fluctuation structure (such as a standing wave or a characteristic mode), realize disturbance, energy dissipation and mode breaking of the liquid sloshing main frequency, and effectively suppress the generation of resonance.

[0028] The asymmetric arrangement is equivalent to setting multiple turbulence points on the liquid surface, each point has different disturbance frequency, intensity and direction, forming a multi-frequency disturbance superposition field, and reducing the energy concentration effect of the main liquid surface through nonlinear interaction.

[0029] The asymmetric arrangement can improve the coverage efficiency of the turbulence structure on the whole liquid surface, involves phase dislocation interference of multiple positions, and is beneficial to continuously play a role under different liquid levels and different wave angles.

[0030] 4. The LNG carrier liquid surface sloshing suppression device provided above, in use, the gas pressure in the gas containing portion can be adjusted through the gas pressure adjusting assembly, so as to adjust the suppression effect of the liquid surface sloshing and adjust the stress when the liquid surface sloshing suppression device is unevenly stressed. Combined with the support of the counterweight plate arranged on the back of the gas containing portion, the service life of the liquid surface sloshing suppression device can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1A structural diagram of a liquid surface sloshing suppression device for LNG carriers;

[0032] Figure 2 This is a structural diagram of an LNG carrier surface sloshing suppression device in another embodiment;

[0033] Figure 3 for Figure 1 Exploded view of a liquid surface sloshing suppression device for LNG carriers;

[0034] Figure 4 for Figure 2 Cross-sectional view of a liquid surface sloshing suppression device for LNG carriers;

[0035] Figure 5 for Figure 1 Cross-sectional view of a liquid surface sloshing suppression device for LNG carriers;

[0036] Figure 6 Figure 1 Structural block diagram of the central airbag;

[0037] Figure 7 for Figure 2 Diagram showing the operational status of a liquid surface sloshing suppression device for LNG carriers.

[0038] Figure 8 for Figure 7 Cross-sectional view of a liquid surface sloshing suppression device for LNG carriers;

[0039] Figure 9 for Figure 7 A cross-sectional view of the LNG carrier's liquid surface sloshing suppression device after the air chamber has been evacuated (Figures 3 to 4 and 5 show the paths of reflection or refraction of LNG liquid by the folds).

[0040] Figure 10 This is a diagram illustrating the usage state of the buoyancy component in another embodiment;

[0041] Figure 11 This is a diagram illustrating the usage state of a buoyancy sphere in yet another embodiment.

[0042] Explanation of main component symbols

[0043] 100. LNG carrier surface sloshing suppression device;

[0044] 110. Counterweight plate;

[0045] 120. Airbag; 121. Gas containment section; 121a. Gas containment cavity; 121b. Baffle groove; 122. Protrusion;

[0046] 140. Gas sensor;

[0047] 150, lifting assembly; 151, telescopic rope; 152, winding disc; 153, elastic spring; 154, buoyant member; 155, fixed pulley; 156, floating ball. DETAILED DESCRIPTION

[0048] The embodiments of the present application will be described below in conjunction with the accompanying drawings. It is obvious that the described embodiments are only some of the embodiments of the present application, but not all of the embodiments.

[0049] It should be noted that when one component is considered to be "connected" to another component, it can be directly connected to the other component or can exist with a middle component. When one component is considered to be "provided on" another component, it can be directly provided on the other component or can exist with a middle component. The terms "top", "bottom", "upper", "lower", "left", "right", "front", "back", and the like used herein are for illustrative purposes only.

[0050] The embodiments of the present application provide a LNG carrier liquid surface sloshing suppression device 100, comprising:

[0051] A counterweight plate 110.

[0052] An air bag 120 is sleeved on the outer surface of the counterweight plate 110 to isolate the counterweight plate 110 and the liquid natural gas. The air bag 120 is formed with a gas containing part 121 on the side of the counterweight plate 110 facing the LNG liquid surface, and the gas containing part 121 is formed with a gas containing cavity 121a.

[0053] The liquid contact surface of the gas containing part 121 in contact with the LNG liquid surface is formed with a plurality of turbulence grooves 121b recessed towards the side where the counterweight plate 110 is located, and the volumes of at least two of the turbulence grooves 121b are different.

[0054] Please refer to Figures 1-3 In this embodiment, when in use, the LNG carrier liquid surface sloshing suppression device 100 is placed in the liquid storage tank, the liquid contact surface of the air bag 120 is in contact with the LNG liquid surface, and the air bag 120 is submerged under the gravity of the counterweight plate 110, so that the liquid contact surface of the air bag 120 is partially immersed in the LNG liquid.

[0055] When the ship is sailing, the LNG liquid in the storage tank will be shaken due to waves, ship movement and other factors. The main liquid level fluctuation will be transmitted to the liquid contact surface on the air bag 120. At this time, due to the different volumes in the plurality of spoiler grooves 121b, the natural frequency of the LNG liquid in each spoiler groove 121b is different, thereby generating multi-frequency local disturbance. These disturbances destroy the energy concentration of the main liquid surface dominant frequency through nonlinear interaction, at the same time, the spoiler structure makes the liquid generate vortex and shear flow in the groove, resulting in the enhancement of local turbulent flow and viscous dissipation. Finally, the liquid swing amplitude is suppressed to avoid the formation of resonance condition.

[0056] The air bag 120 covers the counterweight plate 110 to avoid direct contact of metal with LNG liquid and prevent damage due to cold brittleness or thermal expansion difference of the structure at extremely low temperature. It should be noted that the air bag 120 can be fixed on the counterweight plate 110 by clamping, bonding, embedding and the like, so as to prolong the service life of the counterweight plate 110, avoid direct contact of the counterweight plate 110 with the LNG liquid, and prevent the risk of cold brittleness or heat exchange.

[0057] The gas containing cavity 121a is generally a hollow structure for adjusting the local buoyancy and buffering the liquid impact.

[0058] It should be noted that the counterweight plate 110 is generally a rectangular plate and is made of austenitic stainless steel or aluminum alloy and the like, so that the counterweight plate 110 will not easily deform at the temperature of the LNG liquid. The counterweight plate 110 can provide sufficient stiffness and strength to cope with the impact force generated by the violent fluctuation of the LNG liquid surface in severe sea conditions.

[0059] The air bag 120 is generally a "mountain" shaped structure, and the side away from the counterweight plate 110 is recessed inward to form a spoiler groove 121b. The shape of the spoiler groove 121b can be a rectangular groove, a circular groove, an elliptical groove and the like, including but not limited to the above shapes. The air bag 120 is made of a deformable material, such as a multi-layer composite fluororubber, a liquid silicone rubber and the like.

[0060] The at least two spoiler grooves 121b have different volume sizes to realize a multi-frequency interference mechanism to destroy the resonance rule of liquid swing. The spoiler grooves 121b with different volumes disturb the liquid flow path, dissipate energy and disperse frequency, thereby effectively suppressing the liquid surface fluctuation.

[0061] The spoiler grooves 121b with different volume sizes provide multiple frequencies, which are staggered with the main wave resonance frequency of the liquid, thereby reducing the probability of resonance.

[0062] When the liquid hits the spoiler groove 121b, vortex, shear flow and small scale additional resistance are generated in the interior of the spoiler groove 121b, which effectively converts the liquid kinetic energy into local turbulent dissipation, reduces the overall liquid column movement strength, and reduces the impact load on the inner wall of the storage tank.

[0063] It needs to be further explained that the volume of the turbulence groove 121b is different, which can be caused by one or more of the width, length, and depth.

[0064] It needs to be further explained that since the air bag 120 wraps the weight plate 110, if the LNG transport ship liquid surface sloshing suppression device 100 is placed in the film type liquid storage tank for use, it can prevent the sharp parts on the weight plate 110 from scratching or impacting the film type liquid storage tank, and avoid damaging the film type liquid storage tank.

[0065] In at least one embodiment of the present application, a plurality of said turbulence grooves 121b are asymmetrically arranged on said liquid contact surface.

[0066] Please refer to Figures 1-3 and Figure 6 In this embodiment, during the LNG transport ship is running, the weight plate 110 presses the gas containing part 121 to below the LNG liquid surface under the action of gravity, so that the gas containing part 121 is immersed in the LNG liquid.

[0067] In the case of LNG transport ship sloshing, the main wave of LNG liquid acts on the liquid contact surface, so that the liquid in each turbulence groove 121b starts to slosh with it. Due to the different shapes and volumes of each turbulence groove 121b, the response frequency and coupling path of each turbulence groove 121b are different.

[0068] The plurality of turbulence grooves 121b are irregularly arranged in space, and the asymmetric arrangement makes the disturbance have directional difference during the propagation on the liquid surface, which will make the wave energy scatter, attenuate and interfere with each other when propagating on the liquid surface, avoiding the formation of uniform phase or vibration mode.

[0069] The multi-directional and uncoordinated disturbance caused by the asymmetric structure will effectively disperse the main wave energy concentration area of the liquid surface, thereby weakening the energy coupling of specific frequency and specific direction, and avoiding the formation of liquid sloshing resonance on the LNG liquid surface.

[0070] The asymmetric arrangement can break the regular reflection and interference phenomenon of the liquid, avoid the energy aggregation in some frequencies or areas, and increase the non-uniformity of the disturbance by spatial asymmetric arrangement, so as to make the disturbance frequency, amplitude and direction more dispersed, which is helpful to form a multi-frequency, random and spatially scattered disturbance mode, and further weaken the ability of liquid sloshing main frequency formation.

[0071] Since the asymmetric disturbance acts on different areas of the liquid surface, the shear and vortex generated thereby have a larger spatial coverage, which enhances the dissipation ability of the overall system.

[0072] Secondly, the asymmetric turbulence layout is less dependent on the liquid level or a single wave direction, and is more adaptable to wave incident direction and frequency. In complex and irregular sea conditions, the LNG transport ship liquid sloshing suppression device 100 can still maintain effective liquid sloshing suppression ability, and improve the universality and practicality of the LNG transport ship liquid sloshing suppression device 100.

[0073] In at least one embodiment of the present application, the gas containing portion 121 comprises a protruding portion 122 protruding away from one side of the counterweight plate 110, the protruding portion 122 is arranged around the outer periphery of the turbulence groove 121b, and the gas containing cavity 121a is at least partially located in the protruding portion 122.

[0074] Please refer to Figures 1-11 In this embodiment, the LNG transport ship liquid sloshing suppression device 100 is placed inside the liquid storage tank before the LNG transport ship starts to run. Under the action of gravity of the counterweight plate 110, the air bag 120 is partially submerged, located below the LNG liquid, and the protruding portion 122 also penetrates into the LNG liquid.

[0075] The protruding portion 122 is part of the air bag 120, is arranged around the turbulence groove 121b, and protrudes away from the counterweight plate 110 (i.e. towards the liquid direction). It not only constitutes the envelope of the gas containing cavity 121a, but also has the function of a "liquid flow guide tongue" or a "waveguide skirt".

[0076] During navigation, when the liquid surface is shaken by the wave, the LNG liquid is shaken, and the disturbance wave formed by the LNG liquid in the turbulence groove 121b will first contact the protruding portion 122. The protruding portion 122 blocks the flow path of the LNG liquid, so that the wave flow no longer propagates linearly, and the disturbed liquid wave is further guided to act on the inner wall of the turbulence groove 121b, realizing multi-frequency decomposition and local turbulent dissipation of disturbance energy.

[0077] Please refer to Figure 4 , Figure 5 The inside of the protruding portion 122 is a hollow structure, has a part of the gas containing cavity 121a, and forms a buffer when the liquid disturbance impacts.

[0078] The protruding portion 122 penetrates into the liquid surface, which is equivalent to setting a non-flat disturbance obstacle structure below the liquid surface, which can cut off, deflect and scatter the shaking wave energy, avoiding the rapid propagation and aggregation of energy on the free liquid surface.

[0079] The protruding portion 122 makes the liquid flow act on the inside of the turbulence groove 121b from multiple angles and directions, improves the strength of local shear, vortex and unstable disturbance formed in the turbulence groove 121b, and enhances the dispersibility of liquid wave energy.

[0080] The protrusions 122 are outwardly (i.e. away from the weight plate 110) raised from the liquid contact surface and serve to physically separate each pair of adjacent turbulence slots 121b into independent liquid disturbance regions.

[0081] The protrusions 122 are generally arc-shaped strips that span between two turbulence slots 121b and form partition protrusions. The protrusions 122 effectively block the LNG liquid coupling path and significantly reduce the probability of resonance.

[0082] In at least one embodiment of the present application, a portion of the gas containing cavity 121a is located between the turbulence slot 121b and the weight plate 110.

[0083] Please refer to Figures 1-11 In the present embodiment, the liquid surface sloshing wave is transmitted to the liquid contact surface of the air bag 120 and causes local LNG liquid disturbance in the turbulence slot 121b. With the aid of the air pressure regulating assembly connected to the gas containing cavity 121a, the cavity can be actively inflated or deflated to change the internal gas pressure, and the gas containing cavity 121a region between the turbulence slot 121b and the weight plate 110 will respond with volume compression or expansion.

[0084] At high gas pressure, the cavity rigidity is enhanced, the turbulence slot 121b responds more rigidly, and the response to high frequency disturbance is enhanced. At low gas pressure, the cavity is softer, the turbulence slot 121b responds more flexibly, and is more suitable for low frequency buffering, thereby achieving controllable adjustment of the turbulence efficiency, response sensitivity, dissipation mode, etc.

[0085] Under different working conditions, the main wave frequency and amplitude of the LNG liquid surface are different. By adjusting the gas pressure in the gas containing cavity 121a corresponding to the turbulence slot 121b, the damping and elastic response mode of the turbulence slot 121b can be dynamically changed to more accurately match the main wave disturbance characteristics, which helps to always maintain an efficient disturbance state and suppress the generation of liquid sloshing resonance.

[0086] It should be noted that in the present embodiment, the plurality of turbulence slots 121b are adjusted by one gas containing cavity 121a for overall adjustment.

[0087] At the same time, the gas containing cavity 121a corresponding to each group of turbulence slots 121b can be independently controlled, thereby constructing a local area disturbance adjustable array system to achieve multi-region differentiated turbulence.

[0088] In at least one embodiment of the present application, the number of gas containing portions 121 is multiple, and any gas containing portion 121 has an independent gas containing cavity 121a and at least one turbulence slot 121b.

[0089] Please refer to Figures 1-11 In the present embodiment, a plurality of gas containing portions 121 are provided in the region of the LNG sloshing suppression device 100 facing the LNG liquid surface, each gas containing portion 121 is independently closed and not connected to each other, and each gas containing portion 121 is provided with a turbulence groove 121b on the liquid contact surface thereof.

[0090] When the ship is sailing, the LNG liquid in the liquid storage tank is affected by waves, pitch, roll and other factors to generate liquid sloshing, and the liquid surface fluctuation contacts the turbulence groove 121b region of the plurality of gas containing portions 121, and the liquid generates local turbulence in the turbulence groove 121b. Due to the different volumes of each turbulence groove 121b, the turbulence grooves 121b at different positions generate different frequency differences due to the differences in wave height, phase and direction, and at the same time, the gas containing cavities 121a corresponding to each turbulence groove 121b independently respond to the liquid pressure disturbance to compress or release, thereby playing a buffering role.

[0091] Each gas containing portion 121 has a turbulence capacity, which improves the spatial resolution of disturbance response and enables more local fluctuations to be intervened in time.

[0092] The plurality of turbulence grooves 121b generate disturbances at different spatial positions, and the volume and response frequency of each turbulence groove 121b are different, which forms an equivalent spatially distributed multi-frequency disturbance source array, which can destroy the liquid sloshing main frequency aggregation through nonlinear interaction and prevent the liquid surface from resonating.

[0093] Combined with the gas pressure adjusting assembly and the gas sensor 140, each unit can be used as an independent adjustment module. When the fluctuation in a certain region is enhanced, the pressure in the gas containing cavity 121a of the unit can be increased to make the turbulence more rigid, and when the fluctuation in a certain region is gentle, the pressure in the gas containing cavity 121a can be reduced to increase the flexibility.

[0094] Secondly, even if one or several modules fail, the remaining modules can still continue to work, which helps to improve the stability of the LNG sloshing suppression device 100 in long-time operation or sudden situations.

[0095] In at least one embodiment of the present application, the plurality of gas containing portions 121 are arranged in an asymmetric manner on the side of the counterweight plate 110 facing the LNG liquid surface.

[0096] Please refer to Figures 1-11In the present embodiment, during the navigation of the ship, the LNG liquid level appears free to swing under the influence of waves, changes in speed, etc. The liquid level fluctuation is transmitted to the plurality of gas containing portions 121 in contact therewith. Each gas containing portion 121 receives the fluctuation energy at different phases and intensities due to different positions, directions and angles, thereby triggering the plurality of spoiler grooves 121b to intervene in the liquid level fluctuation in different ways, at different frequencies and with different response amplitudes.

[0097] The asymmetric arrangement makes the interference irregular in space, effectively destroying the regular motion of the liquid in the liquid storage tank, such as mirror reflection, harmonic superposition and resonance mode.

[0098] The asymmetric disturbance source can disperse the regular fluctuation structure (such as standing wave or characteristic mode) of the liquid free surface in the storage tank, realize the interference, energy dispersion and mode breaking of the liquid swing main frequency, and effectively suppress the generation of resonance.

[0099] The asymmetric arrangement is equivalent to setting multiple spoiler points on the liquid surface. Each point has different disturbance frequency, intensity and direction, forming a multi-frequency disturbance superposition field, and reducing the energy concentration effect of the main liquid surface through nonlinear interaction.

[0100] The asymmetric arrangement can improve the coverage efficiency of the spoiler structure on the whole liquid surface, involves phase dislocation interference of multiple positions, and is beneficial to continuously play a role under different liquid levels and different wave angles.

[0101] Under the action of complex or multi-directional waves, the liquid surface disturbance distribution is usually not symmetrical. The asymmetric structure layout is more easily matched with the wave field characteristics under real working conditions, thereby having better disturbance resistance adaptability.

[0102] In at least one embodiment of the present application, at least the gas containing portion 121 has different normal projection area on the counterweight plate 110.

[0103] Please refer to Figures 1-11 In the present embodiment, each gas containing portion 121 has different normal projection area. The size, shape, internal gas cavity volume and spoiler surface size of each gas containing portion 121 are different. Under the action of liquid level fluctuation, the gas containing portions 121 with different projection areas show different liquid frequencies due to different wave receiving areas, structural stiffness and spoiler sizes.

[0104] The LNG liquid surface is excited by waves to generate a swing, the liquid contact surface of each gas containing part 121 is affected by the wave, and the disturbance is transmitted to the spoiler groove 121b and the protruding part 122. At this time, due to the differences in volume, rigidity, and gas compressibility, the gas containing parts 121 of different areas generate inconsistent disturbances and buffering effects, multiple disturbance modes interact, and a liquid swing intervention mechanism with multiple frequencies, multiple amplitudes, and multiple time scales is formed. Different disturbance response frequencies and damping behaviors are generated, which can effectively disperse the concentration of liquid surface wave energy and inhibit resonance.

[0105] The small-area containing part is faster and suitable for disturbing high-frequency small-amplitude fluctuations, and the large-area containing part is slow in response but stable and suitable for weakening low-frequency large-amplitude fluctuations. The two parts work together to cover a wider frequency bandwidth of liquid swing disturbance control range.

[0106] In at least one embodiment of the present application, the LNG carrier liquid surface swing suppression device 100 further comprises:

[0107] A gas pressure adjusting assembly (not labeled in the figure) connected with the gas containing part 121, the gas pressure adjusting assembly is used to charge or exhaust gas to the gas containing part 121 to adjust the pressure in the gas containing part 121; and a gas sensor 140 arranged in the gas containing part 121 for detecting the pressure in the gas containing part 121.

[0108] Please refer to Figures 1-11 In this embodiment, as the ship sails and the wave environment changes, the LNG liquid surface begins to swing to different degrees, the main liquid surface disturbance is transmitted to the gas containing part 121, triggering the spoiler and buffering behavior.

[0109] The gas sensor 140 monitors the pressure change in the gas containing cavity 121a in real time, which can be used to judge the external liquid pressure intensity, liquid level fluctuation frequency, etc.

[0110] Based on the detection results or preset programs, the gas pressure adjusting assembly is started, and the gas is charged: the internal gas pressure of the containing cavity is increased, the rigidity is increased, and the rebound and reduction ability of high-frequency and high-amplitude fluctuations is enhanced; the gas is exhausted: the gas pressure is reduced, the containing cavity is softer, thereby absorbing the energy of low-frequency and wide-amplitude liquid swing and buffering its influence, and the response strength and time characteristics of the spoiler structure are adjusted in real time.

[0111] By adjusting the gas pressure in the gas containing cavity 121a, the compressibility and support rigidity thereof are directly changed, thereby indirectly adjusting the key parameters such as the dynamic deformation and fluctuation response frequency of the spoiler groove 121b, and adapting to different fluctuation working conditions.

[0112] The LNG carrier liquid surface sloshing suppression device 100 has multiple state working capabilities, such as rigid reinforcement mode, flexible buffering mode, energy-saving standby mode, etc., by adjusting the system, so that the LNG carrier liquid surface sloshing suppression device 100 can actively enter the optimal state according to the speed, wave height, and liquid level change.

[0113] The plurality of gas containing parts 121 are each provided with an independent sensor and a gas pressure adjusting assembly, which can locally respond to and adjust the liquid surface fluctuation at different positions, thereby improving the overall liquid sloshing control precision.

[0114] It should be noted that the gas containing part 121 is a closed structure, and is filled with compressible gas. The gas pressure adjusting assembly includes a micro gas pump, a pressure regulating valve, and a gas sensor 140 which is a pressure transmitter.

[0115] It should be further noted that during use, the gas containing part 121 can be pumped by the gas pressure adjusting assembly, so that the protruding part 122 becomes wrinkled due to low gas pressure. The LNG liquid will generate damping to the LNG liquid during the process of passing through the protruding part 122, thereby slowing down the fluctuation of the LNG liquid.

[0116] In at least one embodiment of the present application, the counterweight plate 110 includes austenitic stainless steel.

[0117] Please refer to Figures 1-11 In the present embodiment, the counterweight plate 110 is made of austenitic stainless steel (such as 304, 316L, etc.), which maintains excellent low-temperature toughness in the low-temperature environment (about -162℃) of the LNG storage tank, does not crack, has good corrosion resistance, avoids rust failure after long-term immersion or contact with LNG vapor, and has good dimensional stability in high-low temperature cycles and is not prone to thermal deformation.

[0118] When the ship sets sail, the liquid sloshing excites the air bag 120 to generate turbulence, and the counterweight plate 110 maintains the overall rigidity of the structure and the stability of the center of gravity, and provides gravity under the action of liquid impact, turbulence cavity deformation, etc. The austenitic stainless steel material ensures that the counterweight plate 110 does not fail due to low temperature or impact stress during the entire sloshing period.

[0119] In at least one embodiment of the present application, the LNG carrier liquid surface sloshing suppression device 100 further comprises:

[0120] The lifting assembly 150 is installed at one end on the inner wall of the liquid storage tank containing LNG, and is fixed at the other end on the air bag 120, so as to allow the air bag 120 to move relative to the inner wall of the liquid storage tank.

[0121] Please refer to Figures 7-11In the embodiment, one end of the lifting assembly 150 is fixed to the inner wall of the liquid storage tank, and the other end is connected to the air bag 120. The lifting assembly 150 can include flexible pull belts, telescopic guide rods, sliding guide rails, pontoon connecting rods, etc. The specific form can be various. The air bag 120 is suspended on the inner wall (bottom wall or side wall) of the tank, and is connected to the tank through the lifting assembly 150.

[0122] The lifting assembly 150 allows the air bag 120 to move up and down with the change of the liquid level. The dynamic positioning can be achieved by the buoyancy of the air bag 120 itself, the balance of the counterweight, or external control (such as a guide rail or an automatic winding and unwinding mechanism). The disturbance groove 121b and the gas containing part 121 are always located in the most effective intervention interval near the liquid surface, thereby ensuring that the LNG tanker liquid surface sloshing suppression device 100 always works.

[0123] The lifting assembly 150 always aligns the air bag 120 with the sloshing area, thereby ensuring that the LNG tanker liquid surface sloshing suppression device 100 always works.

[0124] In one embodiment, the lifting assembly 150 is a telescopic rope 151. One end of the telescopic rope 151 is installed on the inner wall of the liquid storage tank and is wound by a winding disc 152. The other end of the telescopic rope 151 is fixed to the counterweight plate 110 or the air bag 120. The winding disc 152 is internally provided with an elastic spring 153. When the air bag 120 contacts the liquid surface, the buoyancy of the air bag 120, the gravity of the counterweight, the tension of the telescopic rope 151, and the force of the elastic spring 153 jointly act on the air bag 120, thereby causing the air bag 120 to be partially submerged below the LNG liquid surface. The disturbance groove 121b formed on the air bag 120 contains part of the LNG liquid, thereby disturbing the LNG liquid.

[0125] When the LNG liquid surface descends, the telescopic rope 151 is pulled out under the gravity of the counterweight plate 110. At this time, the elastic spring 153 is deformed and accumulates energy. At the same time, the air bag 120 descends to contact the LNG liquid surface to disturb the liquid.

[0126] When the LNG liquid surface rises, the telescopic rope 151 is loosened under the joint action of the buoyancy of the air bag 120 and the elastic spring 153. Under the action of the elastic force of the elastic spring 153, the telescopic rope 151 is retracted to the winding disc 152 to avoid the telescopic rope 151 from being knotted or wound around the air bag 120 or the counterweight plate 110. The winding of the telescopic rope 151 is completed, and the telescopic rope 151 is prevented from interfering with the disturbance effect of the air bag 120.

[0127] In another embodiment, the lifting assembly 150 is a plurality of buoyancy members 154 (including foams, elastic ropes, floating balls 156, etc.). The plurality of buoyancy members 154 are arranged on the side surface part. During the process of the LNG liquid surface rising or descending, the plurality of floating air bags 120 can provide buoyancy to adjust the height of the air bag 120, so that the air bag 120 can contact the LNG liquid surface to form a disturbance area.

[0128] In another embodiment, the lifting assembly 150 is a fixed pulley 155 installed at the bottom or top of the liquid storage tank, a floating ball 156 and a rope, one end of the rope is installed on the gas bag 120 or the counterweight, the other end of the rope is installed on the floating ball 156 through the gap between the fixed pulley 155 and the liquid storage tank.

[0129] When the LNG liquid level rises, the buoyancy of the gas bag 120 is greater than the tension of the rope on the floating ball 156, so that the floating ball 156 is immersed in the LNG liquid, and the rope is offset to the side close to the gas bag 120, when the LNG liquid level drops, the rope is partially released with the movement of the gas bag 120, under the action of the buoyancy of the floating ball 156, the rope is offset to the side close to the floating ball 156, thereby enabling the gas bag 120 to be lifted and lowered in different situations. Secondly, it can ensure that the rope is adjusted with the depth of the LNG liquid to be tight, at the same time, a positioning ring can be arranged inside the liquid storage tank, the rope is passed through the positioning ring, to avoid the rope of the gas bag 120 from being entangled with the rope of the floating ball 156.

[0130] The above only describes the embodiments of the present application, it should be noted that for those skilled in the art, without departing from the creative concept of the present application, improvements can be made, but these all belong to the protection scope of the present application.

Claims

1. A sloshing suppression device for LNG carrier, characterized by, The LNG sloshing suppression device for LNG carrier comprises: a counterweight plate; an air bag, which is sleeved on the outer surface of the counterweight plate to insulate the counterweight plate and liquid natural gas (LNG), and which is provided with a gas containing portion on the side of the counterweight plate facing the LNG liquid surface, and which is provided with a gas containing cavity in the gas containing portion; wherein the liquid contact surface of the gas containing portion, which is in contact with the LNG liquid surface, is provided with a plurality of turbulence grooves recessed toward the side where the counterweight plate is located, the volumes of at least two of the turbulence grooves are different, and the plurality of turbulence grooves are asymmetrically arranged on the liquid contact surface; the gas containing portion comprises a protruding portion protruding away from the side of the counterweight plate, the protruding portion surrounds the outer periphery of the turbulence grooves, and the gas containing cavity is at least partially located in the protruding portion.

2. The liquid surface sloshing suppression device for an LNG carrier according to claim 1, characterized by A part of the gas containing cavity is located between the turbulence grooves and the counterweight plate.

3. The liquid surface sloshing suppression device for an LNG carrier according to claim 1 or 2, characterized by The number of the gas containing portions is plural, and any of the gas containing portions has an independent gas containing cavity and at least one turbulence groove.

4. The liquid surface sloshing suppression device for an LNG carrier according to claim 3, characterized by The plurality of gas containing portions are arranged in an asymmetric manner on the side of the counterweight plate facing the LNG liquid surface.

5. The liquid surface sloshing suppression device for an LNG carrier according to claim 4, characterized by The projected areas of at least the gas containing portions on the counterweight plate are different.

6. The liquid surface sloshing suppression device for an LNG carrier according to claim 1 or 2, characterized by The LNG sloshing suppression device for LNG carrier further comprises: a gas pressure adjusting assembly connected with the gas containing portion, which is used to charge or discharge air to the gas containing portion to adjust the pressure in the gas containing portion; and a gas sensor arranged in the gas containing portion to detect the pressure in the gas containing portion.

7. The liquid surface sloshing suppression device for an LNG carrier according to claim 1 or 2, characterized by The counterweight plate comprises austenitic stainless steel.

8. The liquid surface sloshing suppression device for an LNG carrier according to claim 1 or 2, characterized by The LNG sloshing suppression device for LNG carrier further comprises: a lifting assembly, one end of which is mounted on the inner wall of a liquid storage tank containing LNG, and the other end of which is fixed on the air bag to allow the air bag to move relative to the inner wall of the liquid storage tank.

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