Naphtha Cracking Bottom (NCB) oil was heat reformed at various reforming temperature and time, and the volatile extracts were characterized including yields, molecular weight distributions, and representative compounds. The yield of extract increased as the increase of reforming temperature (360~420℃) and time (1~4 hr). Molecular weight of the as-received NCB oil was under 200, and those of extracts were distributed in the range of 100-250, and far smaller than those of precursor pitches of 380-550. Naphtalene-based compounds were more than 70% in the as-received NCB oil, and most of them were isomers of compounds bonding functional groups, such as methyl (CH3-) and ethyl (C2H5-). When the as-received NCB oil was reformed at 360℃ for 1 hr, the most prominent compound was 1,2-Butadien, 3-phenyl- (24.57%), while naphthalene became main component again as increasing the reforming temperature.

The consequence analysis for the unconfined vapor cloud explosion(UVCE) accident by the continuous release of butane vapor was performed and effects of process parameters on consequences were analyzed in standard conditions. For the case of continuous release(87.8 kg/s) of butane vapor at 8 m elevated height in the debutanizing process of tile naphtha cracking plant operating at 877 kPa ＆ 346.75 K, we found that combustion ranges of dispersed vapor estimated by HMP model were 11.2~120.2 m and overpressures estimated by TNT equivalency model at 200 m were about 37.35~55.1 kPa. Also, overpressures estimated by Model UVCE I based on advective travel time to XLFL were smaller than those estimated by Model UVCE IIbased on real travel time between XUFL and XLFL. At the same time, damage intensities at 200 m and effect ranges by overpressure could be predicted. Furthermore, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, sensitivities of overpressures for UVCE accident by the continuous release were about 5 kPa/atm.

PFO(pyrolized fuel oil) and C10+ oil, which are the residual heavy oils form a NCC(naphtha cracking center), were heat-treated to produce the precursor-pitch for carbon materials. After PFO was initially distilled near 300℃ to separate the volatile matters recovering as high-quality fuel oil, the residuum of nonvolatile precursor-pitch was then thermally pyrolized in the temperature ranges from 350℃ to 450℃. Spinnable isotropic pitch with the softening point of 200℃ and the toluene insolubles of 36wt% was obtained at 365℃, and then was successfully spun through a spinneret(0.5mm diameter). After spinning, an isotropic carbon fiber of 25μm diameter was obtained via oxidation and craboniation procedures. Mesophase spherules began to be observed from the product pitch pyrolized at 400℃, and bulk mesophase with a flow texture was observed above 420℃. In the case of C10+ was the feed was polymerized in the presence H2SO4 at room temperature to increase the molecular weight and then heat-treated gradually up to 200~250℃. The products obtained with the softening point of 80~190℃ were carbonized at 500 and 1000℃ to examine the morphology.