• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.189-195
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• 2000

New concept of LNG-FPSO ship with moonpool and bilge step in bottom is considered and investigated in the point of motion reduction and sloshing phenomena of the cargo and operation tanks. The cargo capacity of the ship of which principle dimensions is L x B x D x t(design) =270.0 x 51.0 x 32.32 x 13.7(m) 16K at 98% loading condition. The two moonpools and rectangular step at bilge part are setted up specially for getting the effect of motion decrease. For the motion analysis, linearized three dimensional diffraction theory with the simplified boundary conditions is used. The six-degree of freedom coupled motion responses are calculated for the LNG-FPSO ship. Viscous effects on the roll motion responses of a vessel are taken into account in this calculation program using an empirical formula suggested by Ikeda, Himeno and Tanaka is used. The case study for the moonpool size had been carried out by theoretical estimation and experimental method. For the optimization of the moonpool size and effect of the step, 9 cases of its size and with and without step are considered. From the results of calculation and experiment, it can be concluded that this designed LNG-FPSO ship have possibility to carry out her missions in the rough sea as for the owner's demand waves condition. The motion responses, especially roll motion, for the designed LNG-FPSO ship are much lower than those of another drillship and shuttle tanker and limit criterions are satisfied. For the check of the cargo tank and operation tank sizes we have performed sloshing analysis in the irregular waves which focuses on the pressure distribution on the tank wall and the time history of pressure and free surface for No.2 and No5. tanks of LNG-FPSO with chamfers. Finally we got the tank size which has no resonance and no impact pressure in all filling in the bow quartering and beam sea.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.119-123
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• 2012

Although LNG storage tanks are very delicate with chloride attack owing to its operating inshore location, specific integrity management system for chloride attack has not been studied so far. As the design warranty life time, about 25 years, has come, to prevent paying huge amount of construction cost and required resources for new alternative storage tanks and manage the life time of operating storage tanks, the basic data of chloride attack is necessary. This study intended to build up basic data for following detailed study to develop technologies for life time management of LNG storage tanks, NT Build 492 method in North Europe was used to test chloride diffusion coefficient for the newly-constructing concrete outer tank. Results of these tests lead us to the conclusion that 90 days diffusion coefficients show 46% of 28 days' due to a large quantity of fly ash mixing and much similar to estimation from concrete process table. It seems resonable to conclude that 90 days specimens are recommended estimating the chloride diffusion coefficient for LNG storage tanks to enhance the reliabilities.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.14 no.2
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• pp.98-107
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• 1985

In this thesis, the Sol-Air temperature distribution for the side-wall of a cylindrical cryogenic storage tank made of nonhomogenious composite layer was studied, in order to calculate the thermal load by Newton's cooling law, when the solar radiation was applied upon the side wall. In the analysis, the atmospheric slab was assumed to be horizontal and infinitely large, and the Sol -Air temperature, which was found by the Net- Radiation method considering the longwave radiation wi th surroundings, was used for boundary condition. Energy equation and boundary conditions were normalized by the defined reference- temperature, and solved. The solutions were developed by the Fourier cosine series. Then, the Sol-Air temperature distribution for the side-wall of LNG storage tank was calculated.

• Journal of the Korean Institute of Gas
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• v.19 no.3
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• pp.32-37
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• 2015

The boil-off-gases(BOG) in cryogenic LNG storage tanks are generating continuously due to the heat leakage and need to be re-liquefied by the effective way. As the present method to reliquefy BOG is using LNG cold energy to be supplied after low pressure primary pump, the demand of LNG flow rate should be over 10 times of BOG produced rate to reliquefy it. This research invented new effective re-liquefaction system having only 3~4 times of LNG flow rate against unit BOG, that the pre-liquefaction process of NGL and the use of high pressure LNG cold energy after secondary pump. By the analysis, it could be high efficient reliquefying system for all amount of BOG treatment even during the summer time, and improvement of operation safety and efficiency of LNG terminal.

• KSTLE International Journal
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• v.7 no.2
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• pp.45-50
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• 2006

In this paper, the leakage safety of prestressed concrete structure including the insulation panels has been analyzed using a finite element analysis just after a collapse of 9% nickel inner tank. This FEM study shows that the outer tank may contain the leaked cryogenic liquid for the time being until the primary pump in the inner tank transports stored cryogenic liquids to the nearest LNG storage tank before the outer tank is demolished. This means that the total tank thickness from the insulation panel to the outer tank system safely may retain the leaked cryogenic fluids. The FE computed results indicate that the current structure in a full containment tank is obviously enough to securing the leak-proof safety of the tank system with two primary pumps.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.342-347
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• 2015

Floating LNG is a new concept which is used as LNG regasification/receiving facility and for LNG production/export facility. LNG Floating Production Storage and Offloading(FPSO) concept will put vitality into marginal gas fields which were delayed because of excessive investment cost in the world. LNG Floating Storage Regasification Unit(FSRU) also provides commercially competitive and effective solutions to the areas where onshore infrastructure is not well established. LNG cargo containment system is one of the key functions for FLNG to store produced LNG on a floating structure. This paper presents a new technology related to a LNG containment system; a combined cargo containment system utilizing the advantages of iIndependent tank type and membrane system. Technical advantages have been validated through research work.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.85-91
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• 2001

This paper presents safety analysis of LNG leakage in a prestressed concrete outer tank, which is strongly related on the leak checking effects of the PC structure with and without a residual compression zone based on the BS 7777 codes. The full containment type outer tank which is constructed by a prestressed concrete may be destroyed by leaked cryogenic fluids. The FE calculated results show that the total leak checking time of the PC structure with $10\%$ residual compression zone is about 9 days for $-162^{\circ}C$ liquids. But, three primary pumps in an inner tank may operate to send cryogenic fluids for 6 days, which are stored in an inner tank of $140,000m^3$ capacity This means that the prestressed concrete outer tank may be safe for $-162^{\circ}C$ cryogenic fluids leaked from the demolished inner tank.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.54-60
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• 2004

In this paper, the maximum von Mises stress and maximum displacement of the corner protection and secondary bottom structures have been analyzed using a finite element analysis technique. The design criterion of the comer protection is 1,500Pa for a normal nitrogen gas purging process at the beginning stage of start-up procedure. This pressure is very safe for the structure safety of the comer protection and secondary bottom plates. The corner protection and secondary bottom plates fabricated by $9\%$ nickel steel sheet may plastically be distorted and fractured for the increased gas pressure of 8,475Pa, which produces the maximum von Mises stress of 833MPa and maximum displacement of 1.9m at the center of secondary bottom plate.

• 한국가스학회:학술대회논문집
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• no.5
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• pp.105-110
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• 2002

• 한국가스학회:학술대회논문집
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• 2003.05a
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• pp.159-164
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• 2003