The consequence analysis for jet and flash fire accidents by the continuous release of butane vapor was performed and effects of process variables on consequences were analyzed in standard conditions. For the continuous release (87.8 kg/s) of butane vapor at 8m elevated height in the debutanizing process of the naphtha cracking plant operating at 877 kPa, 346.75 K, we found that for the jet fire accident, shape and size of the flame could be predicted and thermal radiation estimated by API model at 200m distance from release point was 1.5kW/$m^2$, and that for the flash fire accident, effect range was 11.2~120.2m. Also, 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, effects of operating pressures on XUFL were smaller