• Title/Summary/Keyword: IMO C-type tank IMO C

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Consideration for IMO Type C Independent Tank Rule Scantling Process and Evaluation Methods (IMO C형 독립탱크의 설계치수 계산과정 및 평가방법에 대한 고찰)

  • Heo, Kwang-hyun;Kang, Won-sik;Park, Bong-qyun
    • Special Issue of the Society of Naval Architects of Korea
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    • 2017.10a
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    • pp.93-104
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    • 2017
  • IMO type C independent tank is one of the cargo containment system specified on IGC code. It is normally adopted for small and medium size liquefied gas carrier's cargo containment system and it can be applied to fuel tank of LNG fueled vessel. This study focuses on rule scantling process and evaluation methods in early design stage of type C independent tank. Actual design results of 22K LPG/Ammonia/VCM carrier's No.2 cargo tank are demonstrated. This paper presents the calculation methods of design acceleration and liquid height for internal design pressure as defined on IGC code. And this paper shows the applied results of classification rules about shell thickness requirement and buckling strength. Additionally this paper deals with evaluation methods of structural strength and cumulative fatigue damage using FE analysis.

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Measurement of Real Deformation Behavior in C-type Lng Mock-up Tank using Strain Gage (스트레인 게이지를 이용한 C-type LNG Mock-up 탱크 내조 실 변형 거동 측정)

  • Jung, Won-Do;Kim, Tae-Wook;Kim, Jeong-Hyeon;Lee, Do-Young;Chun, Min-Sung;Lee, Jae-Myung
    • Journal of Ocean Engineering and Technology
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    • v.30 no.2
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    • pp.117-124
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    • 2016
  • A C-type LNG mock-up tank was constructed to evaluate the durability of the tank and its structural safety. An experimental strain analysis system equipped with strain gages was designed to investigate the structural behavior of the inner tank at a high hydraulic pressure. In addition, the insulation used in the space between the inner tank and outer tank had a compressive strength and the inner tank thickness of the cylindrical shell and hemisphere was 4.0 mm, which was designed to be thinner than the existing rules. The strains on the inner tank were measured with increasing pressure, and these measurements were compared and analyzed at the strain gage attachment points.

Evaluation of Insulation Performance and Structural Integrity of an IMO Type C LNG Storage Tank (IMO Type C LNG 저장 탱크의 단열성능 및 구조적 건전성 평가)

  • Park, Heewoo;Park, Jinseong;Cho, Jong-Rae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.7
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    • pp.1-7
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    • 2021
  • Restrictions on the emissions of nitrogen oxides, sulfur oxides, carbon dioxide, and particulate matter from marine engines are being tightened. Each of these emissions requires different reduction technologies, which are costly and require many pieces of equipment to meet the requirements. Liquefied natural gas (LNG) fuel has a great advantage in reducing harmful emissions emitted from ships. Therefore, the marine engine application of LNG fuel is significantly increasing in new ship buildings. Accordingly, this study analyzed the internal support structure, insulation type, and fuel supply piping system of a 35 m3 International Maritime Organization C type pressurized storage tank of an LNG-fueled ship. Analysis of the heat transfer characteristics revealed that A304L stainless steel has a lower heat flux than A553 nickel steel, but the effect is not significant. The heat flux of pearlite insulation is much lower than that of vacuum insulation. Moreover, the analysis results of the constraint method of the support ring showed no significant difference. A553 steel containing 9% nickel has a higher strength and lower coefficient of thermal expansion than A304L, making it a suitable material for cryogenic containers.

Thermal Analysis Comparison of IMO with USCG Design Condition for the INGC During the Cool-down Period (급냉각기간에서 IMO설계조건과 USCG 설계조건에 대한 LMGC 화물탱크의 열해석 비교)

  • Lee, Jung-Hye
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.11
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    • pp.1390-1397
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    • 2004
  • This study is concerned with the thermal analysis during the cool-down period of 135,000㎥ class GT-96 membrane type LNG carrier under IMO and USCG design condition. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls down from -4$0^{\circ}C$ to -l3$0^{\circ}C$, and the spraying rate for the cooling of the insulation wall increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the first barrier and the first insulation, which are among the insulation wall, especially in the top side of the insulation wall under IMO and USCG design condition. Also, as the NG temperature distribution is fixed, the outer temperature condition under the design condition has influence on the temperature variation at the insulation. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted under IMO and USCG design condition. From the comparison between two conditions; IMO design condition shows more severe temperature gradient than USCG design condition, therefore, it provides the conservative estimation of the BOG.

An experimental study on fatigue performance of cryogenic metallic materials for IMO type B tank

  • Lee, Jin-Sung;You, Won-Hyo;Yoo, Chang-Hyuk;Kim, Kyung-Su;Kim, Yooil
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.4
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    • pp.580-597
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    • 2013
  • Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low ($-100^{\circ}C$) and cryogenic ($-163^{\circ}C$) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083-O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.

A Study on the Three-Dimensional Steady State Temperature Distributions and BOR Calculation Program Development for the Membrane Type LNG Carrier (Membrane Type LNG선의 3차원 정상상태 온도분포 및 BOR 계산 프로그램 개발에 관한 연구)

  • 이정혜
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.2
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    • pp.140-149
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    • 1999
  • This study is on the development of the computer program that calculates a 3-D hull temperadistribution and analyzes BOR(Boil off rate) to be important to the heat design of a membrane type LNG carrier. The quarter of a tank is taken as an calculation model. And the thermal conductivity of insulation is assumed to be the function of a temperature. In the present steady state calculation, the temperature of LNG in a cargo tank is assumed to be -$162^{\circ}C$ and the air temperature of a cofferdam, to be +$5^{\circ}C$. The lowest air temperature in compartments is calculated as $21.39^{\circ}C$ under the USCG condition ($T_{air}=-18^{\circ}C,\;T_{sw}=O^{\circ}C)$ and B.O.R value is O.0977%/day under the maximum boil-off condition, IMO IGC ($T_{air}=45^{\circ}C,\;T_{sw}=32^{\circ}C$), which satisfies the requirement by KOGAS. The calculated temperature distribution over tank panels at each condition is maximum 3% less than GTT's results. From the results of this study, it can be concluded that the present design of LNG cargo tank satisfies the requirement by KOGAS.

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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.

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%.

A Study on Thermal Performance Evaluation Procedures of LNG Fuel Tank (LNG 연료탱크의 단열성능 평가 절차에 관한 연구)

  • Cho, Sang-Hoon;Sim, Myung-Ji;Jung, Young-Jun;Kim, Ik-Soo
    • Journal of the Korean Institute of Gas
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    • v.22 no.3
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    • pp.45-52
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    • 2018
  • As guidelines for exhaust gases of ship are reinforced by the International Maritime Organization, the necessity for LNG fuelled ship is emerging. The relevant research is actively progressing to develop technologies and promote commercialization. When the residual quantity of LNG fuel tank is less than 70% by consuming fuel during operation, sloshing should be considered. We applied the Type C LNG fuel tank because medium sized LNG fuelled ships are difficult to equip with re-liquefaction system. Structural integrity and thermal performance are very important, especially in LNG fuel tanks that apply to LNG fuelled ship. Through this study, we proposed evaluation procedure of thermal performance for the Type C LNG tank, and verified the validity and effectiveness of BOR(Boil-Off Rate) test Procedure by comparing and analyzing changes in temperature, pressure, BOG(Boil-Off Gas).