• 대한기계학회논문집B
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• 제23권5호
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• pp.653-660
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• 1999

This work describes analysis on the effect of inlet air cooling by the cold energy of liquefied natural gas(LNG) on the performance of gas turbines. Gas turbine off-design analysis program to simulate the influence of compressor inlet temperature variation is prepared and an inlet air cooler is modeled. It is shown that the degree of power augmentation is much affected by the humidity of inlet air. If the humidity is low enough, that is the water content of the air does not condense, the temperature drop amounts to $18^{\circ}C$, which corresponds to more than 12% power increase, in case of a $1350^{\circ}C$ class gas turbine with methane as the fuel. Even with 60% humidity, about 8% power increase is possible. It is found that even though the fuel contains as much as 20% ethane in addition to methane, the power improvement does not change considerably. It is observed that if the humidity is not too high, the current system is feasible oven with conceivable air pressure loss at the inlet air cooler.

• Journal of Advanced Marine Engineering and Technology
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• 제40권3호
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• pp.174-179
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• 2016

해양의 환경오염을 줄이기 위하여 LNG 운송선박, 벙커링 선박 및 LNG를 연료로 추진되는 선박의 건조가 증가하고 있다. 이러한 LNG 선박의 저장탱크들은 외부로부터의 열유입으로 증발가스가 지속적으로 발생하고 있으며, 최근 국내 조선사들은 이 BOG를 재액화하여 회수하는 장치를 개발하여 보급하고 있다. 본 연구에서는 부분재액화 처리장치들의 이론적 최대 재액화 수율을 분석하고 재액화 수율에 미치는 영향 인자들을 비교하였다. 해석결과, BOG와 플래시 가스가 보유한 냉열을 열교환으로 간접 이용하는 부분재액화 처리장치는 최대 48.7%가 되었으며, BOG와 플래시 가스가 혼합 합체되어 냉열이 직접 이용되는 부분재액화 처리장치는 최대 41%로 해석되었다. 또한 액체 수율에 크게 영향을 미치는 인자로는 열교환기의 효율로 열교환기의 성능과 단열이 매우 중요한 것임을 알 수 있다.

• 한국초전도ㆍ저온공학회논문지
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• 제22권3호
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• pp.20-24
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• 2020

The purpose of this analytic study is to design and examine an efficient hydrogen liquefaction cycle by using a pre-cooler. The liquefaction cycle is primarily comprised of a pre-cooler and a refrigerator. The fed hydrogen gas is cooled down from ambient temperature (300 K) to the pre-cooling coolant temperature (either 77 K or 120 K approximately) through the pre-cooler. There are two pre-cooling methods: a single pre-coolant pre-cooler and a cascade pre-cooler which uses two levels of pre-coolants. After heat exchanging with the pre-cooler, the hydrogen gas is further cooled and finally liquefied through the refrigerator. The working fluids of the potential pre-cooling cycle are selected as liquid nitrogen and liquefied natural gas. A commercial software Aspen HYSYS is utilized to perform the numerical simulation of the proposed liquefaction cycle. Efficiency is compared with respect to the various conditions of the heat exchanging part of the pre-cooler. The analysis results show that the cascade method is more efficient, and the heat exchanging part of the pre-coolers should have specific UA ratios to maximize both spatial and energy efficiencies. This paper presents the quantitative performance of the pre-cooler in the hydrogen liquefaction cycle in detail, which shall be useful for designing an energy-efficient liquefaction system.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권1호
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• pp.34-45
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• 2007

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a solid $CO_2$ production ratio. The present study shows that much reduction in both $CO_2$ compression power (only 35% of the power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency (55.3% at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a solid $CO_2$ production ratio increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• 대한조선학회논문집
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• 제55권5호
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• pp.415-420
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• 2018

The development of sail gas has increased the production of ethane as well as natural gas. The decline in the market price for ethane has led to a change in the petroleum-based ethylene production process into an ethane-based ethylene production process and an increase in the ethane/ethylene trade volume. Large-scale ethane/ethylene carrier have been needed due to an increase in long-distance trade from the US, and cargo type change have leaded to consider a liquefaction process to re-liquefy Boil-Off gas generated during the voyage. In this paper, the liquefaction system of Liquefied Ethane Gas carrier was evaluated with Low-GWP (Low-Global Warming Potential) refrigerant and process parameters, Boil-Off Gas pressure and expansion valve outlet pressure, were optimized. Low-GWP refrigerants were propane (R290), propylene(R1270), carbon dioxide(R744) was considered at two type of liquefaction process such as Linde and cascade cycle. The results show that the optimal pressure point depends on the individual refrigerant and the highest liquefaction efficiency of carbon dioxide (R744) - propane (R290) refrigerant.

• Journal of Advanced Research in Ocean Engineering
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• 제3권3호
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• pp.125-135
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• 2017

The paper considers the practical application of the FMEA(Failure Mode and Effect Analysis) method to assess the operational reliability of the LNG(Liquefied Natural Gas) transfer system, which is a potential problem for the connection between the LNG FPSO and LNG carrier. Hazard Identification (HAZID) and Hazard operability (HAZOP) are applied to identify the risks and hazards during the operation of LNG transfer system. The approach is performed for the FMEA to assess the reliability based on the detection of defects typical to LNG transfer system. FTA and FMEA associated with a probabilistic risk database to the operation scenarios are applied to assess the risk. After providing an outline of the safety assessment procedure for the operational problems of system, safety assessment example is presented, providing details on the fault tree of operational accident, safety assessment, and risk measures.

• 기술사
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• 제12권3호
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• pp.12-17
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• 1979

액화천연가스사업은 산가스현지에서 가스정의 개발과 액화기지 건설운영사업 액화가스의 수송사업, 가스소비수입국에서 액화가스의 수하기립 운영사업의 삼자가 자본과 기술의 협력하에서 이루어지는 조직적 협력체계의 사업이다. 그린고로 삼자간에는 이해관계가 밀접하게 결부되 있어 연료의 기본적 요건인 장기안정공급과 가격안정이라는 중요한 요건은 부수적으로 충족되여야만 한다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.181-184
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• 2006

당사에서는 액체산소 (LOX)와 액체메탄 (LNG)를 추진제로 사용하며, 고성능의 터보펌프가 장착된 추력 10톤급 액체로켓 엔진의 개발에 성공하였다. 이러한 개발 성공은 액체메탄을 이용한 재생냉각에 대한 성능 입증, 액체산소와 액체메탄으로 구동되는 터보펌프에 대한 성능 입증, 가스발생기에 의한 터보펌프의 구동 및 추진제 가압 성능 확인, 등을 완벽히 구현함으로써 메탄 엔진 (CHASE-10)의 상업화에 보다 근접하였다고 할 수 있다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.36-36
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• 2017

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.233-234
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• 2006

LNG is extremely cold, $-160^{\circ}C$ in its liquid state. When it vaporizes, returning to its natural state (re-vaporization), it cools its surroundings. This is cold energy. The manufacturing of liquid air is the first processes developed as the most effective utilization of LNG cold. In this paper, adopting the LNG cold process for manufacturing liquid air was developed and analysed. The result showed that as the higher air pressure and adapting nitrogen precooling, liquefaction rate and cumulative mass was increased.