• 동력기계공학회지
• /
• 제18권6호
• /
• pp.113-119
• /
• 2014

Due to the development of the petroleum refining technology and continuously increased demand from markets, a quantity of gasoline and diesel oil produced from a restricted quantity of crude oil has been increasing, and residual fuel to be used at marine diesel engines has been gradually becoming low quality. As a result, it was recently reported that trouble oils which cause abnormal combustion such as knocking with extreme noise and misfire from internal combustion engines were increasing throughout the world. In this study, an author investigated ignitability and combustion quality by using combustion analyzer with constant volume(FCA, Fuel Combustion Analyzer) and middle speed diesel engine about MDO(Marine Diesel Oil), HFO(Heavy Fuel Oil), LCO(Light Cycle Oil) and Blend-HFO which was blended LCO of 1000 liters with HFO of 600 liters. Moreover, for betterment of ignitability and combustion quality of injected fuels, multi-injection experiment was carried out in the diesel engine using Blend-HFO. According to the results of FCA analysis, ignitability and combustion quality was bad in the order of MDO

• Journal of Welding and Joining
• /
• 제32권1호
• /
• pp.79-86
• /
• 2014

The purpose of this study is to determine the proper fillet weld size for the stiffeners on hull bottom plate of crude oil tanker. To achieve it, the effective notch stress and hot spot stress of the fillet weld with leg length specified in the rule were evaluated by using comprehensive FE analyses. Based on the results, the fatigue damages at each location of weld were calculated. Meanwhile the transitional behavior of initial welding distortion in the hull bottom plate under the design conditions was investigated by using a non-linear FEA. Welding distortion and residual stress introduced during fabrication process were considered as initial imperfections. According to FE analysis results, if the fillet leg length satisfies the design criteria of the classification society, the concern on the root failure at the fillet welds in the bottom hull plate during the design life can be negligible. In addition, considering the transitional behavior of the distortion during the service life, the fillet leg length should be minimized.

• 한국대기환경학회지
• /
• 제16권5호
• /
• pp.477-485
• /
• 2000

The data set was collected on fifty-eight different days with a 24-h sampling period from October 27, 1995 through August 25, 1996. From the chemical mass balance (CMB) analysis of $PM_{2.5}$ in the Chongju area, the contributions from soil, gasoline, diesel, light and heavy oil combustion were 2.6%, 15.4%, 9.0%, 28.8% and 1.5%, respectively. Residual $NO_{3}^{-}$), residual $SO_{4}^{2-}$ and residual OC, possibly formed in the atmosphere. represented additional 8.0, 10.2, and 1.6% of the $PM_{2.5}$, respectively. Other unidentified sources constituted the remaining 22.9%. From the CMB analysis, the $PM_{2.5}$ source contribution for fall, winter, spring and summer were 92, 76.8, 77.5 and 59.2%, respectively.

• Fibers and Polymers
• /
• 제2권4호
• /
• pp.178-183
• /
• 2001

A pitch precursor for a general purpose carbon fiber was prepared by condensation of pyrolized fuel oil (petroleum residual oil) with bromine under nitrogen blowing. such a condensation raised the softening point of the pitch from 4$0^{\circ}C$ to $265^{\circ}$ with a yield of 43%. The pitch precurosr showed an enhanced aromaticity and enlarged molecular size, which led to a reduction in molecular mobility and optical isotropy. The precursor was spun into fibers of $20\mu\textrm{m}$ diameter at a take-up speed of 700m/min. The fiber was stepwise stabilized in air and carbonized in Ar gas to obtain an isotropic carbon fiber. The carbon fiber exhibited tensile strengths of 500-800 ㎫though the fiber was formed via a crude method. The electric conductivity of the carbon fiber was relatively high, 2.2$\times$$10^2$S/cm, sufficient to be used as electrode materials.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2002년도 추계 학술발표회 논문집
• /
• pp.147-152
• /
• 2002

본 연구에서는 검증된 Bench급 석탄 가스화 공정에 대하여 개발된 동적모사 프로그램을 중잔유 가스화 공정 모델에 적용하여 가스화 성능에 크게 영향을 미치는 주요변수, 즉 시료 투입비, 산소 공급비, steam 공급비 및 압력조절밸브 열림궤도의 영향을 파악하고, 공정변수들의 동특성을 해석하였다. 가스화기의 부하변동에 따른 주요 공정 변수들의 변동경향 및 시상수에 대한 신뢰성 있는 모사결과를 얻을 수 있었으며, 개발된 모델을 사용하여 중잔유 가스화 공정설계를 위한 기초 자료를 마련하였다.

• Journal of Welding and Joining
• /
• 제34권2호
• /
• pp.16-21
• /
• 2016

Recent keywords of the heavy industries are large-scale structure and productivity. Especially, the sizes of the commercial vessels and the offshore structures have been gradually increased to deliver goods and explore or produce oil and natural gas in the Arctic. High heat input welding processes such as electro gas welding (EGW) have been widely used for welding thick steel plates with flux-cored arc welding (FCAW), especially in the shipbuilding industries. Because high heat input welding may cause the detrimental effects on the fracture toughness of the welded joint and the heat affected zone, it is essential to obtain the sufficient toughness of welded joint. There are well known that the fracture toughness like CTOD, CVN, and KIC were very important factors in order to secure the safety of the structures. Furthermore, the welding residual stress should be considered to estimate the unstable fracture in both EGW and FCAW. However, there are no references on the welding residual stress distribution of EGW and FCAW with thick steel plates. Therefore the welding residual stresses were very important elements to evaluate the safety of the welded structure. Based on the measurement results, the characteristics of residual stress distribution through thickness were compared between one-pass electron gas welding and multi-pass flux-cored arc welding. The longitudinal residual stress in the multi-pass flux-cored arc welding is tensile through all thicknesses in the welding fusion zone. Meanwhile, longitudinal residual stress of EGW is tensile on both surfaces and compressive at the inside of the plate. The magnitude of residual stresses by electron gas welding is lower than that by flux-cored arc welding.

• 해양환경안전학회지
• /
• 제23권1호
• /
• pp.98-103
• /
• 2017

이 연구는 초음파 에너지의 공동현상(Cavitation)을 이용하여 선내 제조된 혼합연료유의 문제점을 개선하고 혼합연료유의 안정적인 사용이 가능하도록 하여 선박운용비의 상당부분을 차지하는 연료비를 절감하고자 한다. 실험은 선내 혼합연료유 제조 방식을 모사하여 선박용 연료유 M.G.O(Marine Gas Oil)와 MF-180(Marine Fuel-oil 180)를 각각 부피비 기준으로 0.25:0.75 및 0.75:0.25 비율로 혼합하였으며 초음파 처리장치를 이용하여 혼합연료유에 초음파 에너지를 직접 조사하여 초음파 에너지가 혼합연료유에 미치는 영향에 관해 고찰하였다. 실험결과, 선내 혼합유 제조시 보고되었던 문제점을 확인하였으며, 혼합시료유의 초음파 조사 후 잔류탄소량은 최대 28.4 % 감소하였다. 또한, 잔류탄소량 감소 및 분산 안정성 분석결과를 토대로 초음파 에너지에 의한 캐비티의 붕괴압이 연료입자 미립화에 효과가 있고, 중질연료유가 많이 함유된 혼합연료유의 일시적인 가용성을 높일 수 있을 것으로 판단되었다.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2000년도 추계 학술발표회 논문집
• /
• pp.45-48
• /
• 2000

중잔유는 다른 유류나 석탄에 비해 높은 황 함유율을 나타내는 특징을 지닌 원유 정제 후 남는 잔여물질로서 환경적인 측면에서 볼 때, 유황제거효율이 높은 시스템의 연료로 사용하는 것이 타당하고, 지속적으로 강화되고 있는 대기오염물질의 환경규제를 만족시키기 위해 가스화 복합발전 시스템의 연료로서 사용하는 것이 중잔유의 활용도 측면에서도 매우 유리한 점을 가지게 된다. 이미 기술 선진국을 중심으로 중잔유의 활용방안에 대한 연구 및 실용화 단계가 진행중이며, 특히, 전량 수입에 의존하고 있는 원유의 활용을 극대화해야 하는 우리의 입장에서는 환경적인 측면 못지않게 경제적인 측면도 고려하여 연료로서의 중잔유의 사용 타당성을 판단하는 것이 매우 중요하다고 하겠다.(중략)

• Environmental Engineering Research
• /
• 제12권3호
• /
• pp.109-117
• /
• 2007

The characteristics of carbonaceous particles collected from the combustion of Vacuum Residue (VR) in a test furnace have been investigated. The physical and chemical characterization includes particle size, scanning electron microscopy of the surface structure, measurement of porosity, surface area and density, EDX/XRD analyses and measurement of chemical composition. The studies show that the carbonaceous VR particles are very porous and spheroidal, and have many blow-holes on the surface. The particles become smaller and more sponge-like as the reaction proceeds. The present porosity of VR particles is similar to that of cenospheres from the combustion of heavy oil, and the majority of pores are distributed in macro-pores above $0.03\;{\mu}m$ in diameter. Measurements of pore distribution and surface area showed that the macro-pores contributed most to total pore volume, whereas the micro-pores contributed to total surface area.

• 에너지공학
• /
• 제12권1호
• /
• pp.58-64
• /
• 2003

1톤/일급 분류층 가스화기를 사용하여 국내 정유공장에서 발생하는 중질잔사유를 1,000~1,20$0^{\circ}C$의 온도 조건과 3kg/$\textrm{cm}^2$의 압력조건에서 가스화 시켜 CO, H$_2$, $CO_2$, 메탄의 합성가스 발생 농도 변화와 탄소전환율, 냉가스효율을 고찰하였다. 실험 결과 중잔유 공급량 31 /kg/hr인 조건에서 H$_2$ 최대 45%, CO 최대 26%인 가스농도를 보여주었으며, 시료 공급량 20 kg/hr, 산소/시료비가 1.2인 조건에서 탄소전환율은 최대 87%, 냉가스효율은 최대 68%를 얻을 수 있었다. 가스화기 운전의 가장 중요한 변수인 산소량의 변화에 따른 합성가스 농도의 변화는 수소성분의 증가율이 CO와 $CO_2$에 비해 높았으며, 산소/시료비가 0.6에서 1.2로 변화하는 동안 가스화기의 온도는 11$0^{\circ}C$ 정도 증가하였다. 또한, 가스화기 온도 증가에 따른 메탄농도의 감소폭은 온도가 높을수록 컸으며, 메탄농도와 가스화기 온도간에는 가스화기 온도를 유추할 수 있는 상관관계가 있었다.