• Title/Summary/Keyword: Vacuum perlite

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Thermal Analysis on the LNG Storage Tank of LNG Bunkering System Applied with Double Shield Insulation Method (LNG 벙커링용 이중 단열적용 LNG 저장탱크 열해석)

  • Jung, Il-Young;Kim, Nam-Guk;Yun, Sang-Kook
    • Journal of the Korean Institute of Gas
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    • v.22 no.4
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    • pp.1-6
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    • 2018
  • An LNG bunkering system stores LNG in a horizontal IMO's C-Type tank insulated with perlite powder, and $10^{-2}$ Torr vacuum in the annular space between the double walls. Current storage tanks have high heat leakage, evaporating over 2.0% daily. A more efficiently insulated storage tank reducing the evaporation rate is required to develope. This research carried out thermal analysis on a new effective insulation method, i.e. double shield insulation system, that separates high super vacuum in the annular space between two tanks with a perlite vacuum in the back side of outer tank. This highly efficient insulation system obtained an evaporation rate of 0.16% per day under a $10^{-4}$ Torr vacuum. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 5.23% than the present perlite system of 4.9%.

Thermal analysis of LNG storage tank for LNG bunkering system (LNG 벙커링용 고효율 LNG 저장탱크 열해석)

  • Yun, Sang-kook
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.9
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    • pp.876-880
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    • 2015
  • In 2016, the IMO's new rules for an 80% reduction in NOx emissions in newly built ships will necessitate the use of LNG as a clean fuel. So far, the developed European countries have led the development of LNG bunkering ships and related facilities. An LNG bunkering system stores LNG in a horizontal or vertical IMO "C"-Type tank insulated with perlite powder, and a vacuum in the annular space between the double walls, like the cryogenic liquid nitrogen tank. Current storage tanks have high heat leakage, evaporating over 2.0% daily, and are difficult to build with the required vacuum. A more efficiently insulated storage tank could reduce the evaporation rate. This research carried out thermal analysis on a new effective insulation method that separates high vacuum in the annular space between two tanks with a solid insulation material, such as urethane foam, lining the outer vessel. This highly efficient insulation system obtained an evaporation rate of 0.03% per day under a $10^{-3}torr$ vacuum, and an evaporation rate of 0.11% at $10^{-45}torr$. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 4.12% than the present perlite system of 4.9%. This newly developed tank can increase the efficiency of LNG storage tank and may help keep LNG bunkering systems safe.

Weldment Design of Supports for Cryogenic Storage Tank considering Insulation (단열을 고려한 초저온 액체질소 저장 탱크의 지지대 용접부 설계)

  • Choi, Dong-Jun;Oh, Jung-Taek;Jung, Jae-Hyun;Cho, Jong-Rae
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.1
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    • pp.131-136
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    • 2008
  • The double-walled steel vessel with powder insulation in the space between the walls is used to minimize heat transfer by radiation and conduction in cryogenic storage tank. The vacuum required the insulation is much less extreme than with high-vacuum or multilayer insulations. The solid supports are used to bear the weight of the inner container. Thermal and structural analysis of the tank have been carried out to study the effect of vacuum and weldment geometry of the internal supports. Heat flux in wall is increased with increasing of thermal conductivity of perlite. Heat flux and stress of support is not affected by weldment geometry.

Experimental research about thermal insulation performance of various powder insulation methods (다양한 파우더 충전 단열 방법의 단열 성능에 대한 실험적 연구)

  • Kim, H.S.;Jeong, S.;Jeong, S.H.
    • Progress in Superconductivity and Cryogenics
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    • v.12 no.3
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    • pp.49-54
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    • 2010
  • This paper presents apparent thermal conductivity of various powder at different vacuum levels for cryogenic insulation. Four kinds of powder insulator are examined by using boil-off calorimetry at pressure range from 50 Torr to 3 mTorr. The first material is perlite which is widely used in cryogenic application. Microsphere is the second one that is recently proposed as a replacement powder for liquid hydrogen storage tanks. It is a hollow sphere made of silica with the diameter in the order of 10 to $100{\mu}m$. Popped rice and polystyrene beads are also selected as candidates for powder insulation even though they are polymers. With their porous elliptic and spherical configuration and light density, they demonstrate fairly good thermal insulation performance at pressure range from 50 Torr to 3 mTorr. According to the experimental investigation in this paper, microsphere and polystyrene beads possess promising insulation characteristic as powder insulators and further study is desired.

A Study of Mechanical Characteristics at Room/Cryogenic Temperature of Powder Insulation Materials Applied to Type C Fuel Tank (Type C 연료탱크에 적용되는 분말형 단열 소재의 상온/극저온 기계적 특성에 관한 연구)

  • Kim, Tae-Wook;Oh, Jae-Won;Seo, Young-Kyun;Han, Seong-Jong;Lee, Jae-Myung
    • Journal of the Korean Society of Industry Convergence
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    • v.24 no.6_2
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    • pp.787-793
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    • 2021
  • The global demand for Liquefied Natural Gas(LNG) continues to increase and is facing a big cycle. To keep pace with the increase in international demand for LNG, the demand for LNG fueled ships is also increasing. Since LNG fuel tanks are operated in a cryogenic environment, insulation technology is very important, and although there are various types of insulation applied to Type C tanks, multi-layer insulation and vacuum insulation are typically applied. Powder insulation materials are widely used for storage and transportation of cryogenic liquids in tanks with such a complex insulation structure. In this study, compression tests at room and cryogenic temperature were performed on closed perlite, glass bubble, and fumed silica, which are representative powder insulation material candidates. Finally, the applicability to the Type C fuel tank was reviewed by analyzing the experimental results of this study.