The domestic shipbuilding industry is building high-value-added ships such as LNG and LPG, and the demand for natural gas, a clean energy source, is continuously increasing. Climate change, such as global warming, is occurring due to rising oil prices and excessive use of fossil fuels. To protect their homes from the changing environment, 121 countries announced intensive climate target policies to reduce carbon emissions to 0% by 2050. In this study, modeling and design were performed using SUS410 and SUS304L about the operating part of the Pilot valve based on the physical properties of the aluminum alloy used in the Pilot valve, a component of the gas pressure Regulating valve for LNG ships. Numerical We want to develop the optimal Pilot valve by comparing and analyzing the results using ANSYS, an analysis simulation program.

Due to stricter environmental regulations of the International Maritime Organization (IMO), the number of ships fueled by Liquefied Natural Gas (LNG) is rapidly increasing. The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) limits the material of tanks that can store cryogenic substances such as LNG. Among the materials listed in the IGC Code, ASTM A553M-17 has been recently adopted as a material for LNG fuel tank projects because of its excellent mechanical properties at cryogenic temperatures. In shipyards, this material is being used to build tanks through Flux Cored Arc Welding (FCAW). However, there is a problem that magnetization occurs during welding and there is a big difference in welding quality depending on the welding position. In order to overcome this problem, this study intends to conduct basic research to apply laser welding to ASTM A553M-17 material. As a result of analyzing the bead shape according to laser BOP speed and Energy density performed in this study, it was confirmed that the penetration and energy density are proportional but the penetration and BOP speed are inverse proportional to some extent. In addition, a range of suitable welding speed and energy density were proposed for the 6.1mm thickness material performed in this study.

Due to stricter environmental regulations of the International Maritime Organization (IMO), the number of ships fueled by Liquefied Natural Gas (LNG) is rapidly increasing. The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code) limits the material of tanks that can store cryogenic substances such as LNG. Among the materials listed in the IGC Code, ASTM A553M-17 has been recently adopted as a material for LNG fuel tank projects because of its excellent mechanical properties at cryogenic temperatures. In shipyards, this material is being used to build tanks through Flux Cored Arc Welding (FCAW). However, there is a problem that magnetization occurs during welding and there is a big difference in welding quality depending on the welding position. In order to overcome this problem, this study intends to conduct basic research to apply laser welding to ASTM A553M-17 material. In Part I, the bead shape according to the welding output was analyzed and in PART II, ​​the penetration phenomenon according to the welding speed was analyzed after Bead on Plate (BOP) test. As a result of analyzing the bead shape according to laser power performed in this study, it was confirmed that the laser power and penetration depth are proportional to some extent. In addition, a range of suitable welding power was proposed for the 6.1mm thickness material performed in this study.

국제항해에 종사하는 모든 선박은 황 함유량 0.5% m/m 이하의 선박연료유를 사용해야만 한다. 따라서 글로벌 해운기업들은 이러한 규제조치에 대응하기 위하여 저유황유의 사용, 혼합유의 사용, 탈황설비(scrubber)의 신규 설치, LNG 연료 전환 등과 같은 다양한 옵션을 해당 회사의 재무사정, 신조발주계획, 중장 기 항로배치, 글로벌 얼라이언스(alliance) 정책 등을 종합적으로 고려하여 신조 발주를 선택하고 있다. 왜냐하면 선박용 LNG 연료는 기존의 고유황유를 대체 하면서 해양환경을 보호할 수 있는 궁극의 수단은 아니지만 현실 가능한 대체 수단으로 평가되고 있기 때문이다. 국내외 조선·해운산업계는 친환경연료추진 선박, 예컨대 암모니아 또는 수소, 연료전지 등과 같이 탄소중립형선박을 건조하여 운항하는 것이 최종목표이지만, 제반 환경을 고려하였을 때 중간단계로서 반드시 LNG 연료추진선박을 고려하지 않을 수 없다. 따라서 이 연구는 향후 상업적인 관점에서 조선소에서 대두될 LNG 연료추진선박에 대한 LNG 연료공 급과 관련된 선박건조보험상의 주요 쟁점들을 법적으로 검토하고, 개선방안을 도출하여 향후 선박용 LNG 연료공급사업의 활성화에 필요한 기초자료를 제공 하였다.

본 논문에서는 LNG 추진선박에서 발생하는 BOG(boil-off gas)를 이용하여 수소를 생산하고 수소 연료전지 시스템을 보조엔진으로 적용한 개질공정의 특성에 대한 연구를 수행했다. 연구를 위해 BOG 수증기 개질공정을 UniSim R410 프로그램을 이용해 공정설계하고, 개질기의 출구온도와 압력, SCR(steam carbon ratio)에 따른 생성물의 분율과 반응물의 소모량을 산출하였다. 연구 결과 개질온도가 890℃일 때 메탄의 반응률이 100 %였으며, 최대 수소 생산량을 보였다. 또한 개질압력이 낮을수록 반응 활성도가 높았다. 하지만 그 이상의 온도가 되면 역반응의 우세로 인해 수소의 생산량은 감소하게 되고, 물과 이산화탄소의 양은 증가했다. 또한 SCR이 증가할수록 수소 생산량도 증가했으나 요구되는 에너지 소비량도 비례하여 증가했다. SCR이 1.8일 때 수소분율이 가장 높았으나 코킹방지를 위해 SCR이 3에서 운전하는 것이 최적 운전범위임을 확인했다. 그리고 개질압력이 낮을수록 발생되는 이산화탄소의 양은 증가했으며, 냉각 및 액화를 위해서는 이산화탄소 발생량을 기준으로 42.5 %의 LNG 냉열이 요구됨을 알 수 있었다.

The use of LNG(Liquefied Natural Gas) in transport is a suitable option to power, large long distance trucks in areas where gas is transported as LNG because there are indigenous gas supplies and no gas network. The use of LNG in passenger cars is far less viable because on average passenger cars stand idle more often, which would give rise to high evaporative losses. Therefore, the use of LNG requires storage facilities for the cold (-162℃) liquid natural gas at the roadside refueling stations and special fuelling equipment which can handle cryogenic temperatures. This paper investigated fuel supply system of a LNG cylinder, especially adiabatic performance and heat exchanger.