KR101304905B1 - Monitoring system of anti sloshing apparatus - Google Patents

Abstract

Disclosed is a monitoring system of a sloshing inhibiting device. The monitoring system of the sloshing suppression apparatus according to an embodiment of the present invention is installed in the sloshing suppression apparatus in the liquid cargo storage tank and is spaced apart from the plurality of signal transmission sensors for transmitting a position signal, the plurality of signal transmission sensors, It may include a plurality of signal receiving sensor for measuring the displacement with the signal transmission sensor.

Description

MONITORING SYSTEM OF ANTI SLOSHING APPARATUS}

The present invention relates to a monitoring system of a sloshing suppression apparatus, and more particularly, to a monitoring system of a sloshing suppression apparatus for suppressing sloshing in a liquid cargo storage tank.

In general, various types of ships are being manufactured to transport liquid cargo by sea. For example, in order to transport liquid cargoes such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), and crude oil, hulls are manufactured according to the characteristics of each cargo. Specific types of liquid cargo storage tanks have been applied to ensure that they are sealed and kept warm.

One of the major loading conditions in the manufacture of such hull and liquid cargo storage tanks is the sloshing problem. Sloshing is a liquid cargo having a free surface because the liquid cargo receives kinetic energy continuously due to the movement of the hull. As referring to the behavior of a fluid that shakes sharply and causes a strong impact on the inner wall of the liquid cargo storage tank, this sloshing is considered from the beginning of the construction of the hull and the liquid cargo storage tank.

As such, the shape of the hull and the liquid cargo storage tank has been designed to minimize the sloshing caused by the liquid cargo and at the same time to withstand the expected sloshing load. In order to avoid the sloshing load, Shipowners had to accept conditional service conditions with limited cargo load. Nonetheless, due to the uncertainty of the sloshing load, various problems with the damage of unexpected liquid cargo storage tanks continue to arise.

This problem of sloshing has to be solved not only in ships but also in fuel tanks in aerospace, aviation, and automobile fields.In contrast to ships, in the case of ships or aircrafts, fuel tanks are caused by rapid maneuvers such as 360-degree rotation. The problem of sloshing in the direction of controlling the flow of liquid cargo, e.g. liquid fuel, was more important because it was more important to smoothly supply fuel rather than simply reinforcing the structure of the fuel tank. I have solved it.

In addition, the conventional liquid cargo storage tanks to prevent sloshing by the liquid cargo in most of the liquid cargo storage tank is filled with a buoy of a porous material is adopted to suppress the movement of the liquid cargo.

The above anti-sloshing method is theoretically possible, but in the case of marine liquid cargo storage tanks, the inside of the liquid cargo storage tank is so large that it is not practically easy to completely fill the buoys. It is difficult to adopt because it is cumbersome to remove it again.

In addition, for ships, it is not only easy to make buoys of liquid cargo storage tank size to suppress sloshing, but also it is difficult to make buoys suitable for cryogenic environments such as LNG, and it is difficult to produce buoys to prevent sloshing. When the buoy is manufactured to be integral with the cargo storage tank, even though these buoys are designed to withstand the behavior of the liquid cargo storage tank, they may damage the walls of the liquid cargo storage tank by interference with the walls of the liquid cargo storage tank. It is not only difficult to install such buoys inside the thermally sealed liquid cargo storage tank, but also has the problem of sacrificing the loading space inside the liquid cargo storage tank.

In order to solve such a sloshing problem, the applicant of the present invention has proposed in Korean Patent No. 1043622 (Prior Art 1) a plurality of buoyant bodies having buoyancy to float on the surface of liquid, an open cell ) Structure and includes a foam member surrounding the buoyancy member and connecting means for connecting the adjacent buoyancy members to each other.

The sloshing suppressing device is characterized in that it is located inside the liquid cargo storage tank to suppress sloshing while directly interacting with the flow of the liquid cargo. This feature has been used to predict and evaluate actual sloshing loads and phenomena only in model tests, since the flow inside cryogenic liquid cargo storage tanks cannot be monitored.

Prior Art 1: Korean Patent No. 1043622

The present invention is to provide a monitoring system of a sloshing suppressor that can monitor the flow of the liquid cargo in the liquid cargo storage tank using a sloshing suppressor in real time.

The monitoring system of the sloshing suppression apparatus according to an aspect of the present invention is installed in the sloshing suppression apparatus in the liquid cargo storage tank and is spaced apart from the plurality of signal transmission sensors for transmitting a position signal, the plurality of signal transmission sensors and It may include a plurality of signal receiving sensor for measuring the sensor displacement with the signal transmission sensor.

The sloshing suppression apparatus may include a plurality of buoyancy blocks disposed adjacent to each other, and a plurality of connection means for connecting the plurality of buoyancy blocks to each other, and the signal transmission sensor may be attached to the buoyancy block.

The display device may further include a display unit connected to the signal receiving sensor and displaying the sensor displacement.

The signal transmission sensor may not be attached to the outermost buoyancy block positioned at the outermost of the plurality of buoyancy blocks.

The signal transmitting sensor may be attached to a corner buoyancy block adjacent to a corner of the liquid cargo storage tank of the plurality of buoyancy blocks.

The signal transmission sensor may wirelessly transmit the location signal to the signal reception sensor.

The signal transmission sensor may be attached to an upper surface of the buoyancy block.

The buoyancy block includes a buoyancy body having buoyancy and a buoyancy groove of a size corresponding to the buoyancy body and a foam member surrounding the buoyancy body positioned in the buoyancy groove, wherein the signal transmission sensor is located inside the buoyancy block. Can be located.

The signal transmission sensor may be attached to the surface of the buoyancy body.

The signal transmission sensor may be attached to the inside of the buoyancy body.

The signal receiving sensor may be installed in a liquid dome or a gas dome installed on an upper surface of the liquid cargo storage tank.

The apparatus may further include a plurality of signal connection lines connecting the plurality of signal transmission sensors and the signal reception sensor to each other.

The signal connection line may be connected to the outside of the liquid cargo storage tank through at least one of the liquid dome and the gas dome.

The connecting means may include a plurality of connecting belts installed on an upper surface of the buoyancy block and a fastening member for fastening the connecting belts to each other, and the signal connecting line may be attached to the plurality of connecting belts.

Is installed outside the liquid cargo storage tank, it may further include a signal line length adjusting device for adjusting the length of the signal line.

According to an embodiment of the present invention, the sloshing suppression apparatus in the liquid cargo storage tank is provided, and is provided with a plurality of signal transmitting sensors for transmitting a position signal, a plurality of signal transmitting sensors, and a sensor displacement with a signal transmitting sensor. By including a plurality of signal receiving sensors to measure, the behavior of the sloshing suppressor can be easily monitored outside of the liquid cargo storage tank.

In addition, by using a plurality of signal connecting lines connecting the plurality of signal transmitting sensors and the signal receiving sensor to each other, it is possible to safely and quickly transmit the position signal.

1 is a cross-sectional view showing a state in which a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention is installed inside and outside a liquid cargo storage tank.
2 is a plan view showing a state in which a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention is installed in a liquid cargo storage tank.
3 is a plan view specifically showing a state in which a signal transmission sensor of the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention is installed in the buoyancy block.
4 is a perspective view illustrating in detail a state in which a signal transmission sensor of a monitoring system of a sloshing suppressing apparatus according to a first embodiment of the present invention is installed in a buoyancy block.
5 is a cutaway view illustrating a state in which a signal transmission sensor of the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention is installed inside the buoyancy block in detail.
6 is a cutaway view illustrating a state in which a signal transmission sensor of the monitoring system of the sloshing suppressing apparatus according to the first embodiment of the present invention is installed inside the buoyancy body.
7 is a cross-sectional view showing a state of monitoring a sloshing suppression apparatus using a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention.
8 is a cross-sectional view showing a state in which the monitoring system of the sloshing suppression apparatus according to the second embodiment of the present invention is installed inside and outside the liquid cargo storage tank.
9 is a plan view showing a state in which a monitoring system of a sloshing suppression apparatus according to a second embodiment of the present invention is installed in a liquid cargo storage tank.
10 is a plan view illustrating in detail a state in which a signal transmission sensor of the monitoring system of the sloshing suppressing apparatus according to the second embodiment of the present invention is installed in the buoyancy block.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

1 is a cross-sectional view showing a state in which a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention is installed inside and outside a liquid cargo storage tank, and FIG. 2 is a sloshing suppression according to a first embodiment of the present invention. A plan view showing a state where the monitoring system of the device is installed in a liquid cargo storage tank.

As shown in Figs. 1 and 2, the monitoring system of the sloshing suppression apparatus according to an embodiment of the present invention is installed in the sloshing suppression apparatus 10 in the liquid cargo storage tank 1 and the position signal S A plurality of signal transmission sensors 50 and a plurality of signal transmission sensors 50 spaced apart from the plurality of signal transmission sensors 50 and measuring a sensor displacement d with a signal transmission sensor 50 and a signal. The display unit 70 is connected to the receiving sensor 60.

The sloshing suppressor 10 is a device for controlling the sloshing of the liquid cargo 2 so as to cover the surface of the liquid cargo 2 such as LNG (liquefied natural gas), LPG (liquefied petroleum gas), crude oil, etc. stored in the liquid cargo storage tank 1. [ (2).

At this time, the sloshing suppressing apparatus 10 is configured such that the sloshing suppressing apparatus 10 and the plurality of piping 4 and the like for transporting the liquid, for example, the LNG, which can be stored in the liquid cargo storage tank 1, Or the buoyancy block may not be installed in some areas so as not to hit the edge of the liquid storage tank 1 or the like.

The plurality of signal transmission sensors 50 are not attached to the outermost buoyancy block 111 positioned at the outermost of the plurality of buoyancy blocks 110. Since the outermost buoyancy block 111 is easily in contact with the inner wall of the liquid cargo storage tank 1, the position of the signal transmission sensor 50 may be severely changed by this, and thus it is determined that it represents the behavior of the entire buoyancy block 110. Because it is difficult to do.

The signal transmission sensor 50 may be attached to the corner buoyancy block 112 adjacent to the corner of the liquid cargo storage tank 1 of the plurality of buoyancy blocks 110 by bolting, sewing, gluing, or the like. In addition, the signal transmission sensor 50 may be attached to the plurality of buoyancy blocks 110 through various methods. The corner buoyancy block 112 adjacent to the corner of the liquid cargo storage tank 1 may represent the behavior of the entire buoyancy block 110 since the buoyancy block 110 may exhibit the behavior of the entire buoyancy block 110.

The signal transmission sensor 50 wirelessly transmits the position signal of the buoyancy block 110 to the signal reception sensor 60. The position signal may be a distance signal, a speed signal, or an acceleration signal between the signal transmitting sensor 50 and the signal receiving sensor 60.

The signal receiving sensor 60 may be installed in the liquid dome 61 or the gas dome 62 installed on the upper surface of the liquid cargo storage tank 1.

The liquid dome 61 is a device for transferring the liquid cargo 2 into or out of the liquid cargo storage tank 1, and the gas dome 62 is a liquid generated during the operation of the hull. It is a device that discharges the gas inside the cargo storage tank 1 to the outside.

The display unit 70 is a device for displaying the sensor displacement between the signal transmission sensor 50 and the signal reception sensor 60, and may be a display device or the like.

In this manner, the behavior of the sloshing suppression apparatus 10 can be easily monitored outside the liquid cargo storage tank 1 by using the variation of the sensor displacement between the signal transmitting sensor 50 and the signal receiving sensor 60. .

Hereinafter, a state in which the signal transmission sensor of the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention is installed in the buoyancy block will be described in detail with reference to FIGS. 3 to 6.

3 is a plan view illustrating in detail a state in which a signal transmission sensor of a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention is installed in a buoyancy block, and FIG. 4 is a sloshing according to a first embodiment of the present invention. 5 is a perspective view showing in detail a state in which the signal transmission sensor of the monitoring system of the suppression apparatus is installed in the buoyancy block, and FIG. 5 is a signal transmission sensor of the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention. 6 is a cutaway view illustrating a state installed in the interior of the present invention, FIG. 6 is a cutaway view illustrating a state in which the signal transmission sensor of the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention is installed in the buoyancy body in detail. to be.

As shown in FIGS. 3 and 4, the sloshing suppressing apparatus 10 includes a plurality of buoyancy blocks 110 arranged adjacent to each other, and a plurality of connecting means 120 connecting the plurality of buoyancy blocks 110 to each other. ). The connection means 120 includes a plurality of connection belts 121 installed in the buoyancy block 110 and a fastening member 122 for fastening the connection belts 121 to each other.

The buoyancy block 110 may have a cube or cuboid shape having a length of 1.0-1.5 m in width, length, and height, and vary in size or shape according to the size of the internal space of the liquid cargo storage tank 1. Can be.

The plurality of buoyancy blocks 110 are arranged in a lattice structure, and are simply and stably connected to each other by the connecting belt 121 and the fastening member 122 to cover the surface of the liquid cargo 2, so that the hull pitches during operation. When moving in various directions, such as pitch, roll, and yaw, sloshing by the liquid cargo 2 in the liquid cargo storage tank 1 can be suppressed effectively.

The buoyancy block 110 has a buoyancy body 112 having a buoyancy, buoyancy groove 114a of a size corresponding to the buoyancy body 112, and a foam member surrounding the buoyancy body 112 positioned in the buoyancy groove 114a ( 114 and a cover 116 surrounding the foam member 114.

The buoyant body 112 may be spherical, ellipsoidal or other various structures. The buoyant body 112 may have buoyancy to float on the liquid cargo 2. When the liquid cargo 2 is LNG, the airtight space may be filled with gas such that a gas, As shown in Fig. The buoyant body 112 may have buoyancy due to such structural characteristics, and may have buoyancy depending on the characteristics of the material. The buoyant body 112 may be made of a material having such a strength that the shape is not changed by the buoyant force. In order to sufficiently perform its function even in the cryogenic temperature state by the liquid cargo 2 such as LNG, Alloy. Also, the buoyant body 112 may be made of a foam material having a closed cell structure. That is, the buoyant body 112 itself may be made of a thin foamed material instead of having a hollow structure. Here, the closed cell structure has a buoyancy structure because it does not absorb liquid into the inside of the buoyant body 112. As the buoyant body 112 is made of the foamed material of the closed cell, thermal load, compressive load Even if cracks are generated on the surface of the buoyant body 112 due to the buoyancy of the buoyant body 112, the buoyant body 112 can stably maintain buoyancy since the liquid cargo 2 can not penetrate into the buoyant body 112. In this case, the buoyant body 112 may be formed of a polymer material including any one of a phenol resin, a melamine resin, and a synthetic resin thereof, which can maintain elasticity even at a cryogenic temperature at which the liquid material 2, such as LNG, have.

The foam member 114 surrounds the outer surface of the buoyancy body 112, and the foam member 114 has an open cell structure to more effectively prevent sloshing due to the liquid cargo 2 infiltrating. Can be. Here, the open cell structure has a structure in which a hole penetrating the inside and the outside of the foam member 114 is formed on the outer circumferential surface, so that the surface area of the foam member 114 can be maximized, . ≪ / RTI > The foam member 114 is formed in the open cell structure and the liquid material 2 is impregnated into the foam member 114 so that the buoyancy block 110 is suspended partially in the surface of the liquid material 2, So that the sloping by the liquid cargo 2 in the liquid cargo storage tank 1 can be more effectively suppressed. The foam member 114 may be made of a polymeric material or the like. For example, it is possible to absorb the liquid material 2 even at a very low temperature at which the liquid material 2 such as LNG maintains the liquid phase, , A melamine resin, and a synthetic resin thereof.

The cover 116 encloses the foam member 114 and thereby prevents the foam member 114 from breaking and also prevents the contamination of the liquid cargo 2 by the debris of the partially damaged foam member 114 can do. The cover 116 may be made of a material having durability at room temperature even at a cryogenic temperature.

The signal transmission sensor 50 may be attached to and fixed to the upper surface of the buoyancy block 110. In this case, the signal transmission sensor 50 may be firmly attached to the connection belt 121 positioned on the buoyancy block 110. Therefore, the sensor displacement between the signal transmission sensor 50 and the signal reception sensor 60 can be measured more accurately, so that the behavior of the sloshing suppression apparatus 10 can be accurately identified.

Meanwhile, as shown in FIG. 5, the signal transmission sensor 50 may be firmly attached to the surface of the buoyancy body 112 inside the buoyancy block 110 by bolting, welding, or bonding. In addition, the signal transmission sensor 50 may be attached to the surface of the buoyancy body 112 inside the buoyancy block 110 in various ways. At this time, since the signal transmission sensor 50 does not come into contact with the liquid cargo 2 that is slotted, there is no fear that the signal transmission sensor 50 may be damaged and thus the life of the signal transmission sensor 50 may be long. Therefore, the sensor displacement between the signal transmission sensor 50 and the signal reception sensor 60 can be measured more accurately, so that the behavior of the sloshing suppression apparatus 10 can be accurately identified.

Meanwhile, as shown in FIG. 6, the signal transmission sensor 50 may be firmly attached to the inside of the buoyancy body 112 inside the buoyancy block 110 by bolting, welding, or bonding. In addition, the signal transmission sensor 50 may be attached to the buoyancy body 112 inside the buoyancy block 110 in various ways. At this time, since the signal transmission sensor 50 does not come into contact with the liquid cargo 2 that is slotted, there is no fear that the signal transmission sensor 50 may be damaged and thus the life of the signal transmission sensor 50 may be long. Therefore, the sensor displacement between the signal transmission sensor 50 and the signal reception sensor 60 can be measured more accurately, so that the behavior of the sloshing suppression apparatus 10 can be accurately identified.

Hereinafter, a method of monitoring the sloshing suppression apparatus using the monitoring system of the sloshing suppression apparatus according to the first embodiment of the present invention will be described in detail with reference to FIG.

7 is a cross-sectional view showing a state of monitoring a sloshing suppression apparatus using a monitoring system of a sloshing suppression apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, when the sensor displacement d between the signal transmission sensor 50 and the signal reception sensor 60 is kept constant, the sloshing suppression apparatus 10 may be determined to be operating normally.

However, as shown in FIG. 7, when the sensor displacement d 'between the signal transmission sensor 50 and the signal reception sensor 60 decreases or decreases rapidly, the buoyancy block 110 of the sloshing suppression apparatus 10 is reduced. This folded or dried state can be confirmed through the display unit 70 on the outside of the liquid cargo storage tank (1).

In this way, the liquid cargo storage tank 1 using the signal transmission sensor 50, the signal reception sensor 60, and the display unit 70 provided in the sloshing suppression apparatus 10 in the liquid cargo storage tank 1. It is possible to easily monitor the behavior of the sloshing suppression device 10 from outside.

Meanwhile, although the signal transmission sensor and the signal reception sensor wirelessly transmit the position signal in the first embodiment, the signal transmission sensor and the signal reception sensor may be connected by separate signal connection lines 80.

 Hereinafter, the monitoring system of the sloshing suppression apparatus according to the second embodiment of the present invention will be described in detail with reference to FIGS. 8 to 10.

8 is a cross-sectional view showing a state in which the monitoring system of the sloshing suppression apparatus according to the second embodiment of the present invention is installed inside and outside the liquid cargo storage tank, and FIG. 9 is a sloshing suppression according to the second embodiment of the present invention. 10 is a plan view showing a state in which the monitoring system of the device is installed in the liquid cargo storage tank, and FIG. 10 specifically shows a state in which the signal transmission sensor of the monitoring system of the sloshing suppression device according to the second embodiment of the present invention is installed in the buoyancy block. Top view.

The second embodiment is substantially the same except that the signal transmitting sensor 50 and the signal receiving sensor 60 are connected by separate signal connecting lines 80 as compared with the first embodiment shown in FIGS. Repeated description is omitted.

8 to 10, the monitoring system of the sloshing suppression apparatus 10 according to the second embodiment of the present invention connects the plurality of signal transmission sensors 50 and the signal reception sensor 60 to each other. It includes a plurality of signal connection line 80.

In FIG. 8, for example, the signal connection line 80 is connected to the gas dome 62 through the connection center 81, but is not limited thereto.

The plurality of signal connection lines 80 connected to the plurality of signal transmission sensors 50 are connected to at least one of the liquid dome 61 and the gas dome 62 through the connection center 81, and the signal connection line 80 is One or more of the liquid dome 61 and the gas dome 62 are connected to the outside of the liquid cargo storage tank 1 and to the signal receiving sensor 60.

The signal connection line 80 is attached to the connection belt 121 by bolting, sewing, or bonding, and is firmly fixed. In addition to this, the signal connection line 80 may be attached to the connection belt 121. Therefore, the signal connection line 80 quickly transmits the position signal transmitted from the signal transmission sensor 50 to the signal reception sensor 60 without loss. As long as the signal connection line 80 is not disconnected, the position signal can be transmitted safely.

In addition, since power can be supplied to the signal transmission sensor 50 through the signal connection line 80, a separate power supply line is not required, thereby reducing costs.

Meanwhile, the signal connection line 80 may be connected to the signal connection line length adjusting device 90. The signal connection line length adjusting device 90 may be installed outside the liquid cargo storage tank 1 to adjust the length of the signal connection line 80. Therefore, the signal connecting line length adjusting device 90 may adjust the length of the signal connecting line 80 according to the level of the liquid cargo. The signal connecting line length adjusting device 90 is provided with a shock absorbing device such as a spring so that the signal connecting line 80 is partially loosened when the sloshing suppressing device 10 behaves by sloshing the liquid cargo 2 at the same level. The winding can be repeated. That is, as the sloshing suppressing device 10 is immersed in the liquid cargo 2 according to the change in the water level of the liquid cargo 20, the signal connecting line length adjusting device 90 is connected to the signal connecting line by the tension applied to the signal connecting line 80. 80) length can be adjusted. Therefore, the signal connecting line length adjusting device 90 can prevent the signal connecting line 80 from being damaged by sloshing of the liquid cargo.

The present invention has been described above with reference to the embodiments shown in the drawings. However, the present invention is not limited thereto, and various modifications or other embodiments falling within the scope of the present invention are possible by those skilled in the art. Accordingly, the true scope of protection of the present invention should be determined by the following claims.

1: Liquid cargo storage tank 2: Liquid cargo
10: sloshing suppression device 50: signal transmission sensor
60: signal receiving sensor 70: display unit
80: signal lead 90: signal lead length adjusting device
110: buoyancy block 120: connecting means
112: buoyant body 114: foam member

Claims (15)

A plurality of signaling sensors installed in the sloshing suppression device in the liquid cargo storage tank and transmitting a position signal,
A plurality of signal receiving sensors spaced apart from the plurality of signal transmitting sensors and measuring sensor displacements with the signal transmitting sensors
Lt; / RTI >
The sloshing suppression device
A plurality of buoyancy blocks disposed adjacent to each other, and
A plurality of connecting means for connecting the plurality of buoyancy blocks to each other
/ RTI >
And said signal transmitting sensor is attached to said buoyancy block. delete The method of claim 1,
And a display unit connected to the signal receiving sensor and displaying the sensor displacement. The method of claim 1,
And the signal transmission sensor is not attached to the outermost buoyancy block positioned at the outermost of the plurality of buoyancy blocks. The method according to claim 1 or 4,
And the signal originating sensor is attached to a corner buoyancy block adjacent to a corner of the liquid cargo storage tank of the plurality of buoyancy blocks. The method of claim 1,
And the signal transmitting sensor wirelessly transmits the position signal to the signal receiving sensor. The method of claim 1,
And said signal transmitting sensor is attached to an upper surface of said buoyancy block. The method of claim 1,
The buoyancy block
A buoyancy body having a buoyancy and buoyancy groove of a size corresponding to the buoyancy body and a foam member surrounding the buoyancy body positioned in the buoyancy groove,
The signal transmission sensor is a monitoring system of a sloshing suppression device located inside the buoyancy block. 9. The method of claim 8,
And the signal transmitting sensor is attached to a surface of the buoyancy body. 9. The method of claim 8,
And the signal transmission sensor is attached to the inside of the buoyancy body. The method of claim 1,
And said signal receiving sensor is installed in a liquid dome or a gas dome installed on an upper surface of said liquid cargo storage tank. 12. The method of claim 11,
And a plurality of signal connecting lines connecting the plurality of signal transmitting sensors and the signal receiving sensor to each other. The method of claim 12,
And the signal connection line is connected to the outside of the liquid cargo storage tank through at least one of the liquid dome and the gas dome. The method of claim 13,
The connecting means
A plurality of connecting belts installed on an upper surface of the buoyancy block,
A fastening member fastening the connection belt to each other,
And said signal connection line is attached to said plurality of connection belts. 15. The method of claim 14,
And a signal connection line length adjusting device installed outside the liquid cargo storage tank and configured to adjust the length of the signal connection line.

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