• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.566-572
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• 2005

The most crucial factor in membrane LNG ships to ensure sage operations, is how to effectively control tank pressure at the time of excessive generation of boil off gas (BOG). When the ships carry out tank cool down with her retaining heel prior to arrival at loading port, the vessel encounters the critical situation of excessive BOG and high tank pressure that can lead to high degree of risk. This is to provide one of the best ways to secure safe and effective LNG ship operations focusing on the detailed methods of tank cool down to achieve ATR(Arrival Temperature requirement) without building up high tank pressure and excessive BOG and calculating the appropriate heel quantity to be unutilized for tank cool down and fuel during ballast voyage.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.150-155
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• 2015

Recently, LNG receiving terminals have been widely constructed and expanded for an increase in LNG demand. Selection of the storage tank for send-out and estimation of send-out flow rate have significant influence to process operation and economics. In this study, a send-out flow rate of each storage tank is optimized in order to minimize the total BOG generation rate. Considering a size and characteristic of each storage tanks, BOG flow rates are estimated using a dynamic simulation with varying liquid levels in the tanks. The regression model is developed fitting BOG flow rates and tank liquid levels, which are boil off rate model to predict BOG flow rates with particular level data. The objective function and constraints including required total send-out flow rate and level limit in the tanks are formulated to optimize a send-out flow rate of each tank. This method for optimization of send-out operation is applied to the Incheon LNG receiving terminal considering two scenarios for various liquid levels and maximum and minimum required send-out flow rates. For maximum required send-out flow rate, this method achieves BOG reduction of 9% comparing with assumed conventional operation.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.148-153
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• 2008

As the oil price is dramatically jumping up, the consumption of LNG is rapidly expanding and the size of LNG carriers becomes bigger. For LNG ships, the application of DF (Dual-Fuel) engines gradually increases because of high efficiency, which alternatively use diesel or BOG (Boil-Off Gas) from cargo tank as a fuel. The surplus BOG from LNG cargo tank should be exhausted by GCU or liquefied through the BOG reliquefaction system and returned back. This study focused into its operational characteristics through the process simulation using HYSYS and discussed details on the influence of the variations of some operational parameters such as a distribution ratio by the change of fuel mass flow into the DF engine.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.49-57
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• 2022

If the hydrogen industry is activated in the future, the LH2 receiving terminal with membrane storage tank is a major way to store and send large capacity hydrogen. Since such a LH2 receiving terminal does not currently exist, the process simulation model of it was completed by referring to the design data on existing LNG receiving terminal with same typed storage tank. Based on this model, the amount of BOG generation according to change of design conditions, which is a very important factor in the operation of LH2 receiving terminal, was predicted. Through this, it was attempted to review the appropriate operating conditions to minimize the amount of BOG generated during unloading in LH2 receiving terminal with membrane storage tank.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.827-837
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• 2022

If the hydrogen industry is activated, the introduction of C-type and pressurized liquefied hydrogen (LH2) tank suitable for small and medium-sized transp- ortation and storage will be given priority in the future. Therefore in this paper, the behavior for the LH2 property changes and boil-off gas (BOG) treatment of the C-type cargo tank through voyage of the LH2 carrier and pressurized tank of the LH2 receiving terminal were analyzed through computational simulations by making assumptions about the carrier operation and unloading conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.7
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• pp.485-490
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• 2007

The LNG BOG re-liquefaction system for LNG carriers was designed based on the Claude refrigeration cycle and the thermodynamic analysis was carried out in order to find the design point of the three heat exchangers constituting the system. The thermodynamic analysis revealed that the system state could be defined by the three cold endpoint temperatures of the three-pass heat exchanger. Hence the iso-lines of the specific liquefaction work, taken as the performance indicator, were presented in terms of those three temperatures and discussed. The system was found most economical when those three temperatures approached a single temperature of $-140^{\circ}C$ and thus this system state could be taken as the design point for the heat exchangers.

• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.7-13
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• 2021

The re-liquefaction drum is a product that installed spray nozzles at the top to directly spray overcooled LNG into evaporative gas and installed demistors to facilitate gas separation, which was developed to increase the re-liquidity efficiency of small scale re-liquefaction facilities. In the hydrostatic test of the drum, no leakage occurred even at a pressure of 1.5 times the design pressure, but during the BOR(Boil Off Rate) test, the bolt loosening occurred due to contraction and expansion by temperature change. For the continued use of the product, insulation construction on flange connections was developed to enable detachment and attachment, and the comparison of heat load with existing insulation confirmed that it was very small compared to the inlet flow rate in the drum.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.4
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• pp.342-349
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• 2023

In this study, a numerical simulations were conducted to analyze the phase change behavior of a liquid hydrogen storage container. The effects of gravity direction and hydrogen filling rate on boil-off gas (BOG) in the storage container were investigated. The study employed the volume of fluid, which is the phase change analysis model provided by ANSYS Fluent (ANSYS, Canonsburg, PA, USA), to investigate the sloshing phenomenon inside the liquefied hydrogen fuel tank. Considering the transient analysis time, two-dimensional simulation were carried out to examine the characteristics of the flow and thermal fields. The results indicated that the thermal flow characteristics and BOG phenomena inside the two-dimensional liquefied hydrogen storage container were significantly influenced by changes in gravity direction and hydrogen filling rate.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.34-39
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• 2024

Korea government is trying to supply liquid hydrogen from another country to domestic The research for liquid hydrogen transportation and liquefaction plant of hydrogen underway for several years, and empirical research is also planned in the future. Along with the development of liquid hydrogen transport ship/liquefaction plant technology, the development of liquid hydrogen reception base technology must be carried out. In this study, a concept level liquid hydrogen receiving terminal is constructed based on the process of the LNG receiving terminal. Based on this, a study is conducted on the development of analysis technology for the amount of BOG (pipe, tank) generated during cooldown and unloading in the liquid hydrogen unloading line (loading arm to storage tank). The research results are intended to be used as basic data for the design and liquid hydrogen receiving terminal in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.232-237
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• 2011

Recently, continuous research on cryogenic valves is being carried out with the rapid development of the cryogenic valve-related industry, and especially, high performance of cryogenic valves is being promoted due to the breakthrough development and demand of users, etc., of the mechanical, shipbuilding, semiconductor and display industry and the aerospace industry field, but it is the reality that technical development and research on cryogenic application equipment on vacuum insulation are insufficient. The present research focused on interception of heat exchange with the outside by keeping low pressure after installing a jacket pipe outside a stem and also considered heat transfer properties on changes in pressure of a vacuum part and radius of a jacket which can reduce heat exchange for effective heat transmission control by studying it in a three-dimensional numerical analysis method.