KR20130069692A - Cavitation impact test equipment thereof and test piece for liquefied natural gas cargo containment system - Google Patents

Abstract

PURPOSE: A cavitation impact test device and a specimen thereof for an LNG(Liquefied Natural Gas) cargo storehouse are provided to prevent damage to the cargo storehouse caused by cavitation impact by improving the internal pressure with a structure damping an impact load actuated on a first barrier as impact absorbing members are mounted between the first barrier and a first insulating layer. CONSTITUTION: A cavitation impact test device(100) for an LNG cargo storehouse comprises a base plate(102), a case(104), a collision plate(106), a collision inducer(108), and a sensor(116). A specimen(200) is place on the base plate. The case is arranged on the base plate and receives the specimen. The collision plate is arranged on the surface of a first barrier(210). The collision inducer is arranged to be moved toward the collision plate in the upper part of the specimen for the collision with the collision plate. The sensor is mounted in the rear surface of the specimen for detecting an impact load generated by the collision of the collision inducer with the collision plate.

Description

Cavitation impact attenuation structure impact test device and test specimen for liquefied natural gas cargo hold {CAVITATION IMPACT TEST EQUIPMENT THEREOF AND TEST PIECE FOR LIQUEFIED NATURAL GAS CARGO CONTAINMENT SYSTEM}

The present invention relates to a liquefied natural gas (LNG) cargo hold system (Cargo Containment System), and more specifically, the impact test apparatus and impact cavitation impact reduction structure of the LNG cargo hold for attenuating the impact by cavitation (Cavitation) It relates to test specimens.

Liquefied natural gas refers to a colorless, transparent cryogenic liquid whose natural gas, which contains methane as its main component, is cooled to -162 ° C and its volume is reduced to one hundredth. As such liquefied natural gas is used as an energy resource, an efficient transportation method that can transport a large amount from the production base to the destination of the demand site has been considered to use this gas as energy. Liquefied gas transport ships have been developed that can transport gas by sea.

By the way, the liquefied natural gas transport ship should be provided with a cargo hold (Cargo) that can store and store the liquefied gas liquefied in the cryogenic state, there were a lot of difficulties due to the very demanding conditions.

That is, since LNG has a vapor pressure higher than atmospheric pressure, and has a temperature of approximately -162 ℃ level, in order to safely store and store such LNG, the cargo hold for storing the LNG is a material that can withstand ultra low temperatures, for example, It should be made of aluminum steel, stainless steel, 35% nickel steel, etc., and should be designed with a unique insulation panel structure that is resistant to other thermal stress and heat shrinkage and prevents heat intrusion.

When the liquefied natural gas is transported by a transport vessel, a large pressure shock wave acts on the cargo hold while the liquefied natural gas is vaporized by slewing of the LNG carrier and liquefied again. Such an impact is called a cavitation shock, and since the cargo hold of a ship needs durability to withstand such an impact load, research on this is being actively conducted.

However, when the transport capacity of the LNG cargo tank is large, the movement of the LNG, for example, the sloshing occurs due to the rolling (rolling), pitching (Pitching) of the LNG carrier. At this time, when the pressure of the LNG close to the vaporization point reaches the vapor pressure (Vapor Pressure), a large pressure shock wave acts on the first barrier and the heat insulating material in the process of LNG is vaporized and liquefied again. This action is called cavitation, and the impact exerted by cavitation is called cavitation impact.

When the stress load stress (Stress) caused by the cavitation impact exceeds the strength of the first barrier and the heat insulator, plastic deformation and breakage of the first barrier and the heat insulator occur, and the safety of the cargo hold is lowered. In particular, the wrinkle of the stainless steel sheet is more susceptible to impact load. This impact load acts repeatedly on the first barrier for the period of operation of the LNG carrier, for example about 40 years. Therefore, cargo hold components are required to withstand impact loads for more than 40 years in cryogenic environments.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. SUMMARY OF THE INVENTION An object of the present invention is to provide a cavitation impact attenuating structure of an LNG cargo hold which can absorb the impact load applied to the first barrier by cavitation to improve pressure resistance.

Another object of the present invention is to provide an impact test apparatus for a cavitation impact damping structure of an LNG cargo hold for impact testing of a damping structure that absorbs the impact load applied to the first barrier.

It is still another object of the present invention to provide a specimen for cavitation impact reduction structure impact test of an LNG cargo hold for conducting an impact test of attenuation structure that absorbs the impact load applied to the first barrier.

A feature of the present invention for achieving the above object is a first barrier provided for contacting a surface of LNG for storage of LNG, and having a first panel mounted on the rear surface of the first barrier. A cavitation impact damping structure of an LNG cargo hold, comprising: a plurality of shock absorbing members mounted between the first barrier and the first panel to absorb impact loads acting on the first barrier, the shock absorbing members comprising: a fiber mat; In the LNG cargo hold cavitation impact reduction structure consisting of a first surface sheet and a second surface sheet attached to both sides of the fiber mat in order to flatten the surface and the back surface of the fiber mat and improve handling.

Another feature of the present invention is a cavitation impact attenuation structure impact test apparatus of the LNG cargo hold for impact test of the impact test specimen of the LNG cargo hold having a plurality of shock absorbing members between the first barrier and the first panel. A base plate on which the specimen is placed; A case disposed on the base plate and accommodating the specimen; An impingement plate disposed on a surface of the first barrier; A collision propellant arranged to move toward the collision plate from above the specimen for collision with the collision plate; Cavitation impact attenuation structure impact test apparatus of the LNG cargo hold including a plurality of sensors mounted on the back surface of the specimen to detect the impact load generated by the collision propellant hit the impact plate.

Another feature of the invention is a first barrier provided for contacting the surface of LNG for storage of LNG; A first panel mounted on the back surface of the first barrier; A plurality of impact absorbing members mounted between the first barrier and the first panel to absorb impact loads acting on the first barrier, wherein the first barrier and the first panel are impingement plates placed on the surface of the first barrier; It is in a test specimen for cavitation shock attenuation structure of LNG cargo hold where a collision path is formed for the passage of a collision propellant which collides with and destroys a collision plate.

The cavitation impact attenuation structure of the LNG cargo hold according to the present invention has a shock absorbing member mounted between the first barrier and the first heat insulating layer to improve the internal pressure by a structure that attenuates the impact load acting on the first barrier. The cargo hold can be prevented from being damaged. And the shock absorbing members can be easily constructed by a simple configuration. In addition, the cavitation shock attenuation structure impact test apparatus and impact test specimen of the LNG cargo hold has a useful effect that can be easily carried out the impact test on the cargo hold equipped with shock absorbing members.

1 is a cross-sectional view showing the configuration of the LNG cargo hold is applied to the cavitation impact reduction structure according to the present invention,
Figure 2 is a cross-sectional view showing a partially enlarged cavitation impact reduction structure of the LNG cargo hold according to the present invention,
Figure 3 is a cross-sectional view showing the configuration of the shock absorbing member in the cavitation impact reduction structure of the LNG cargo hold according to the present invention.
4 is a cross-sectional view showing the configuration of the cavitation shock attenuation structure impact test apparatus and impact test specimen of the LNG cargo hold according to the present invention,
5 is a cross-sectional view illustrating the operation of the cavitation impact attenuation structure impact test apparatus and impact test specimen of the LNG cargo hold according to the present invention,
6 is a cross-sectional view illustrating the action of the collision inducing body to destroy the impact plate in the cavitation shock attenuation structure impact test apparatus of the LNG cargo hold according to the present invention.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of the cavitation impact damping structure of the LNG cargo hold and the impact test apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

First, referring to FIGS. 1 and 2, the LNG cargo hold according to the present invention has a first barrier 10 installed inside the inner wall 2 and contacting the LNG to support liquid tightness. The first barrier 10 is composed of a plurality of membranes 12 mounted on the inner side of the inner wall 2. The membranes 12 have a plurality of corrugations 14 that are formed to be capable of contraction and expansion due to thermal deformation. The membranes 12 may be composed of stainless steel sheets. The membranes 12 of the stainless steel sheet are welded along their edges to join two adjacent membranes 12.

A first panel (Panel) 20 is mounted on the back surface of the first barrier 10. The first panel 20 is made up of a plurality of fly-woods 22 mounted on the back surface of the first barrier 10. The first heat insulating layer 30 is mounted on the back surface of the first panel 20. The first heat insulation layer 30 is composed of a plurality of first unit insulation blocks 32. The first unit insulating blocks 32 are heat insulating materials having excellent heat insulating properties, for example, polyurethane foam, sandwich form, micro-celluloid form, nano-celluloid form, and the like. It may be configured as.

As shown in FIG. 1, a second barrier 40 is mounted on the back surface of the first heat insulating layer 30. The second barrier 40 may be made of a sheet made of stainless steel, aluminum, brass, zinc, or the like. And the second insulating layer 50 is attached to the back surface of the second barrier 40. The second heat insulation layer 50 is composed of a plurality of second unit insulation blocks 52. The second unit insulation blocks 52 are arranged so that the interface of each of the first unit insulation blocks 32 and the interface of each of the second unit insulation blocks 52 are shifted from each other to prevent leakage of LNG. The second unit insulation blocks 52 may be formed of polyurethane foam, sandwich foam, micro celluloid foam, nano celluloid foam, or the like. In FIG. 1, the second barrier 40 is mounted on the rear surface of the first heat insulating layer 30 so as to cover the interface between the second unit insulation blocks 52. 40 may be mounted between the first panel 20 and the second heat insulating layer 50 to cover the entire surface of the second heat insulating layer 50.

The second panel 60 is attached to the rear surface of the second barrier 40. The second panel 60 may be composed of a plywood (62), a sandwich panel, or the like. The rear surface of the second panel 60 is attached to the inner surface of the inner wall 2 of the LNG carrier by a mastic (Mastic) 64, the mastic 64 may be composed of an epoxy resin.

1 to 3, a plurality of shock absorbing members 70 are mounted between the first barrier 10 and the first panel 20 to absorb shocks applied to the first barrier 10. have. The shock absorbing members 70 are composed of a fiber mat 72, a first surface sheet 74 and a second surface sheet 76 attached to the front and rear surfaces of the fiber mat 72. The first surface sheet 74 is attached to the rear surface of the first barrier 10, and the second surface sheet 76 is attached to the surface of the first panel 20.

As shown in FIG. 3, the fiber mat 72 is impregnated between the plurality of glass fibers 72a and the glass fibers 72a having a small change in physical properties at cryogenic temperatures to couple the glass fibers 72a in a mat form. It consists of a binder 72b. In this embodiment, the fiber mat 72 may be made of cotton instead of the glass fibers 72a.

The binder 72b may include a fibrous mat 72 made of a thermoplastic polymer such as polypropylene and polyethylene, and a thermosetting polymer such as epoxy and phenol to control rigidity. The first and second surface sheets 74 and 76 are used to planarize the surface of the fibrous mat 72 and to improve the handling of the worker. The first and second surface sheets 74 and 76 may be formed of a polymer film such as a metal sheet or polytetrafluoroethylene (PTFE). Can be configured.

In the cavitation impact attenuation structure of the LNG cargo hold according to the present invention having the configuration as described above, the first barrier 10 receives the impact load due to cavitation during the operation of the LNG carrier. The impact load by cavitation is applied to the surface of the first barrier 10 in a short time of about 1 millisecond (0.001 seconds), and the first panel 20, the first heat insulating layer 30, and the second barrier 40 are applied. , Are sequentially transmitted to the second heat insulating layer 50. At this time, since the unit insulating blocks 32 and 52 of the first and second heat insulating layers 30 and 50 are vulnerable to impact load, they may be damaged.

Meanwhile, the shock absorbing members 70 mounted between the first barrier 10 and the first panel 20 absorb and mitigate the impact load acting on the first barrier 10. In addition, the shock absorbing members 70 improve the internal pressure between the first barrier 10 and the first panel 20. Therefore, since the impact load transmitted from the first barrier 10 to the first heat insulating layer 30 is minimized, breakage of the first and second heat insulating layers 30 and 50 can be prevented.

4 to 6 shows a cavitation impact attenuation structure impact test apparatus of the LNG cargo hold. 4 to 6, the impact test apparatus 100 performs an impact test on the specimen 200 that simulates the cavitation impact attenuation structure of the LNG cargo hold. The impact test specimen 200 may include a shock absorbing member mounted between the first barrier 210, the first panel 220, the first heat insulating layer 230, the first barrier 210, and the first panel 220 ( 270).

The shock absorbing members 270 are composed of a fiber mat 272 and a first surface sheet 274 and a second surface sheet 276 attached to the front and back surfaces of the fiber mat 272. The first barrier 210, the first panel 220, and the shock absorbing members 270 of the specimen 200 may be formed of the first barrier 10, the first panel 20, and the shock absorbing members 70. Since the basic configuration and operation are the same, a detailed description thereof will be omitted. The collision path 280 is formed perpendicular to the first barrier 210, the first panel 220, the first heat insulating layer 30, and the shock absorbing members 270.

The impact test apparatus 100 includes a base plate 102 on which the specimen 200 is placed, a case 104 disposed above the base plate 102, and accommodates the specimen 200. The impingement plate 106 is disposed on the surface of the first barrier 210 to be aligned with the impingement path 280. The collision guide 108 is arranged to move toward the collision plate 106 from above the specimen 200 to collide with the collision plate 106. The impingement plate 106 may be composed of a material, for example, a glass plate, which is weakly brittle so that it may be destroyed when colliding with the impingement conductor 108.

The collision guide tube 110 is mounted through the case 104 to be aligned with the collision passage 280. The collision guide tube 110 has an outlet 114 disposed above the bore 112 and the impingement plate 106 and in communication with the bore 112. The collision inducing body 108 is accommodated in the bore 112 so that the collision plate 106 may be damaged by moving along the bore 112 of the collision induction pipe 110 and hitting the collision plate 106. The impingement body 108 is fired through the outlet 114 after being moved by compressed air supply means, for example, compressed air supplied to the bore 112 of the impingement conduit 110 from the air compressor. A plurality of sensors 116 are mounted on the rear surface of the first heat insulation layer 230 so that the impact inducing body 108 can detect the impact load generated by the collision plate 106. The sensors 116 may be configured as shock sensors.

The operation of the LNG cargo hold according to the present invention having such a configuration is applied to the cavitation shock attenuation structure impact test device.

Referring to FIG. 4, the operator places the specimen 200 on the base plate 102 and covers the specimen 200 with the case 104. The operator places the impingement plate 106 over the first barrier 210. When the collision inducing body 108 is supplied to the bore 112 by the operation of the air compressor in the state where it is located above the bore 112 of the collision induction pipe 110, the collision inducing body ( 108 moves along bore 112 and then fires toward exit plate 106 through exit 114. The collision propellant 108 impinges on the specimen 200 indirectly while hitting the collision plate 106.

5 and 6, the collision plate 106 is broken when colliding with the collision propellant 108, and immediately after the collision plate 106 is damaged, the ability to transmit an impact to the specimen 200 is lost. . When the impingement plate 106 is made of a material having brittleness such as a glass plate, it is possible to significantly reduce the duration of the impact on the specimen 200 because the rate at which the breakage of the glass plate proceeds is very fast.

As such, when the impact plate 106 is broken, the impact load is momentarily transmitted to the specimen 200. The impact test apparatus is configured to impact the cavitation impact acting on the first barrier 10 by the movement of the LNG in the LNG cargo, that is, the rocking. It is simply implemented by the simulation (Simulation) of the (100) and the specimen 200.

On the other hand, the impact load transmitted to the specimen 200 is damaged by the collision plate 106 colliding with the collision propellant 108 is detected by the sensors 116. Therefore, the value of the impact load attenuated by the shock absorbing member 270 according to the impact load detected by the sensors 116 may be calculated.

The embodiments described above are merely illustrative of the preferred embodiments of the present invention, the scope of the present invention is not limited to the described embodiments, those skilled in the art within the spirit and claims of the present invention It will be understood that various changes, modifications, or substitutions may be made thereto, and such embodiments are to be understood as being within the scope of the present invention.

10: first barrier 20: first panel
30: first insulation layer 32: first unit insulation block
40: second barrier 50: second insulating layer
52: second unit insulation block 60: second panel
70: shock absorbing member 72: fiber mat
74: first surface sheet 76: second surface sheet
100: impact test apparatus 102: base plate
104: case 106: collision plate
108: collision propellant 110: collision guide
112: bore 116: sensor
200: Psalm 280: collision path

Claims (5)

Cavitation impact attenuation structure of the LNG cargo hold having a plurality of shock absorbing members between the first barrier and the first panel Cavitation impact attenuation structure impact test apparatus for the LNG cargo hold for the impact test of the test specimen
A base plate on which the specimen is placed;
A case disposed on the base plate and accommodating the specimen;
An impingement plate disposed on a surface of said first barrier;
A collision propellant arranged to move toward the collision plate from above the specimen to collide with the collision plate;
Cavitation impact attenuation structure impact test device of the LNG cargo hold including a plurality of sensors mounted on the back surface of the test piece so that the collision inducing body collides with the impact plate. The method of claim 1,
And a collision inducing conduit mounted to the case and having a bore for receiving the collision inducing body and guiding movement of the collision inducing body.
The impact guide pipe is a cavitation shock attenuation structure impact test device for liquefied natural gas cargo hold for guiding the movement of the collision propellant by the compressed air supplied to the bore. 3. The method according to claim 1 or 2,
The impingement plate is made of a material having brittleness that can be broken by collision with the impingement body,
The test piece is a cavitation impact damping structure impact test device of the LNG cargo hold further comprises a collision passage formed so as to pass through the collision causing body that destroyed the collision plate. A first barrier provided to contact the surface of the liquefied natural gas for storage of the liquefied natural gas;
A first panel mounted on a back surface of the first barrier;
A plurality of shock absorbing members mounted between the first barrier and the first panel to absorb the impact load acting on the first barrier,
Cavitation impact of the LNG cargo hold formed in the first barrier and the first panel is formed a collision path for the collision of the collision plate placed on the surface of the first barrier to destroy the collision plate. Specimens for damping structure impact tests. The method of claim 4, wherein
The plurality of shock absorbing members are a fibrous mat, the first impact sheet and the second surface sheet attached to the surface and the back surface of the fibrous liquefied natural gas cargo hold cavitation impact damping structure impact test specimen.

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