Application of Response Surface Methodology in Study of the Product Yield Distribution of Thermal Cracking of Atmospheric Gasoil

In order to determine the yield distribution of thermal cracking of gasoil, a pilot plant was designed and setup. A systematic experimental design was utilized based on CCD (central composite design). The feed flow rate, steam ratio and temperature were considered as factors to design the experiments. Some statistical models were tuned based on the results of conducted experiments. The models were evaluated with lack-of-fit and R-squared tests. The results of the analysis proved that the models fitted well with the experimental results of the considered products. Based on the experiments and statistical models the pilot plant was optimized in order to maximize the net profit. At the optimum point coil outlet temperature, the feed flow rate and steam ratio were, respectively, equal to 843.8°C, 6.02 g/min and 0.46. Regarding these conditions, the yield of ethylene, propylene and butadiene and rate of coke formation would be 23.82 wt%, 12.13 wt%, 2.42 wt% and 14.44 x 10^-7 g/cm^2.sec, respectively