• Journal of Advanced Marine Engineering and Technology
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• v.40 no.5
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• pp.447-452
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• 2016

The use of gas as fuel, particularly liquefied natural gas (LNG), has increased in recent years owing to its lower sulfur and particulate emissions compared to fuel oil or marine diesel oil. LNG is a low temperature, volatile fuel with very low flash point. The major challenges of using LNG are related to fuel bunkering, storing, and handling during ship operation. The main components of an LNG fuel system are the bunkering equipment, fuel tanks, vaporizers/heaters, pressure build-up units (PBUs), and gas controlling units. Low-pressure dual-fuel (DF) engines are predominant in small LNG-powered vessels and have been operating in many small- and medium-sized ferries or LNG-fueled generators.(Tamura, K., 2010; Esoy, V., 2011[1][2]) Small ships sailing at coast or offshore rarely have continuous operation at constant engine load in contrast to large ships sailing in the ocean. This is because ship operators need to change the engine load frequently due to various obstacles and narrow channels. Therefore, controlling the overall system performance of a gas supply system during transient operations and decision of bunkering time under a very poor infrastructure condition is crucial. In this study, we analyzed the fuel consumption, the system stability, and the dynamic characteristics in supplying fuel gas for operating conditions with frequent engine load changes using a commercial analysis program. For the model ship, we selected the 'Econuri', Asia's first LNG-powered vessel, which is now in operation at Incheon Port of South Korea.

• Journal of Advanced Research in Ocean Engineering
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• v.3 no.3
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• pp.112-124
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• 2017

As an LNG carrier preserves and transports liquefied natural gas under minus $163^{\circ}C$, the cargo tank has to have sufficient hull strength against not only the wave loads but also against loads caused by loading and unloading and thermal expansion to keep the LNG safely. The main insulation types for a CCS are No.96 and Mark III from GTT for the membrane LNG carrier. Particularly, the invar membrane plate in No.96 is very thin and its connections could experience high local stresses owing to such dynamic loads. Therefore, it should be verified whether those connections have sufficient fatigue lives for the purpose of operation and maintenance. This research aims at performing fatigue analysis with 0.1 fatigue damage criteria for 40 years of design life to support new membrane CCS development using proper S-N curves and the associated finite element modeling technique for each connection and then propose a reasonable design methodology.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.881-888
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• 2006

The purpose of this study is to develop a structural. analysis system of LNG pump tower structure. The system affords to build optimized finite element model and procedure of the pump tower structure. The pump tower structure is one of the most important components of LNG (liquefied natural gas) carriers. The pump tower structure is subject to sloshing load of LNG induced by ship motion depending on filling ratio. Three types of loading components, which are thermal, inertia and self-gravity are considered in the analysis. All these design and analysis procedures are embedded in to the analysis system successfully.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.219-220
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• 2003

최근 석유, 석탄을 사용하는 연소시설이 황산화물, 먼지가 배출되지 않는 LNG(Liquefied Natural Gas)로 연료를 전환하고 있다. 점차적으로 LNG 사용이 증가함에 따라 LNG에 의한 대기오염에 대한 관심이 높아지고 있으며, 최근에는 온실가스에 대한 관심도 높아지고 있다. 따라서 털 연구에서는 LNG연소에 의한 온실가스 배출계수와 국내 온실가스 배출량을 연소시설별로 산출하고자 한다. (중략)

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.2
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• pp.200-208
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• 2014

This paper presents thermodynamic performance analysis of organic Rankine cycle (ORC) using low temperature heat source in the form of sensible energy and using liquefied natural gas (LNG) as heat sink to recover the cryogenic energy of LNG. LNG is able to condense the working fluid at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the mathematical model, a parametric analysis is conducted to examine the effects of eight different working fluids, the turbine inlet pressure and the condensation temperature on the system performance. The results indicate that the thermodynamic performance of ORC such as net work production or thermal efficiency can be significantly improved by the LNG cold energy.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.55-62
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• 2015

The liquefaction to produce LNG (liquefied natural gas) is the only practical way for mass transportation of natural gas across oceans, which accompanies considerable energy consumption in LNG plants. Power generation is one of the effective utilization ways of LNG cold energy which evolves during the vaporization process of LNG with sea water. In this work, performance analysis of two cold energy generation processes, direct expansion and organic Rankine cycles, were carried out by using Aspen HYSYS simulation. The results show that the performance of the organic Rankine cycle is superior to the direct expansion.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.21-27
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• 2009

This paper presents the numerical study on the strength safety of the prestressed concrete outer tank for a LNG storage tank, which is manufactured by sets of membrane panels with special corrugations. This study for a finite element analysis assumes that the membrane panel of the inner tank was fractured and the liquefied natural gas stored in the inner membrane tank was leaked to the prestressed concrete outer tank. The stress and displacement of the outer tank have been analyzed for five different loadings, which are originated by a hydrostatic pressure and a weight of a LNG, a temperature difference, a weight of the prestressed concrete and a boil-off gas pressure. The computed FEM results indicate that the PC outer tank with a storage capacity of 200,000$m^3$ has a good strength safety for a leaked LNG from the membrane inner tank, but the increased cryogenic loadings in which are originated by a leaked LNG decreases the strength safety of the PC structure. This may lead to the collapse of the outer storage tank.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.141-147
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• 2010

Liquefied natural gas(LNG) is natural gas that has been converted temporarily to liquid form for ease of storage and transport it. Natural gas is the worlds cleanest burning fossil fuel and it has emerged as the environmentally preferred fuel of choice. In Korea, the demand of this has been increased since the first import from the Indonesia in 1986. LNG takes up about 1/600th the volume of natural gas in the gaseous state by cooling it to approximately $-162^{\circ}C(-260^{\circ}F)$. The reduction in volume therefore makes it much more cost efficient to transport and store it. Modern LNG storage tanks are typically the full containment type, which is a double-wall construction with reinforced concrete outer wall and a high-nickel steel inner tank, with extremely efficient insulation between the walls. The insulation will be installed to LNG outer tank for the isolation of cryogenic temperature. The insulation will be installed in the base slab, wall and at the roof. According to the insulation's arrangement, the different aspects of temperature transmission is shown around the outer tank. As the result of the thermal & stress analysis, by the installing cellular glass underneath the perlite concrete, the temperature difference is greatly reduced between the ambient temperature and inside of concrete wall, also reducing section force according to temperature load.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.307-313
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• 2016

When liquefied natural gas (LNG) is stored in a tank, it is necessary to maintain low temperature. It is very important that insulation techniques are applied to the LNG cargo because of this extreme environment. Hence, laminated wood, especially plywood, is widely used as the structural member and insulation material in LNG cargo containment systems (CCS). However, fracture of plywood has been reported recently, owing to sloshing effect. Therefore, it is necessary to increase the strength of the structural member for solving the problem. In this study, compressed wood, which is used as a support in LNG independent type B tanks, was considered as a substitute for plywood. Compression and bending tests were performed on compressed wood under ambient and cryogenic temperatures to estimate the mechanical behaviors and fracture characteristics. In addition, the direction normal to the laminates surface was considered as an experimental variable. Finally, the feasibility of using compressed wood for an LNG CCS was evaluated from the test results.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.33-40
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• 2011

In the hazardous areas where explosive liquids, vapors and gases exist, electrical apparatus/equipment should have explosion-proof construction. The consuming of liquefied natural gas(LNG) has markedly increased in the industrial field, especially in aspect of some thermoprocessing equipment, boiler, dryer, furnace, annealer, kiln, regenerative thermal oxidizer(RTO) and so on. Because it has many merits, clean fuel, safety, no transportation/storage facility and so on. It is strongly recommend that the classification of hazards has to be decided to prevent and protect explosion which may occur in thermoprocessing equipment. In this paper, the operated thermoprocessing equipments in industrial area investigated and explosion risk assessment about LNG leakage from its facilities was performed through numerical calculation and computer simulation. Finally, we suggest the systemic/technical approach for safety assessments of thermoprocessing equipments consumed LNG fuel which are specially subjected to classification of hazardous area.