Propylene yield assessment utilizing response surface methodology for naphtha pyrolysis cracking

Abstract

The study was carried out at the steam cracker furnace, Short Residence Time (SRT) VII type to investigate the impact of selected input variables on the Propylene Product Yield. The statistical analysis was conducted as normal data after successful outliers and residuals clearance using data stability and normality verification tests. The Response Surface Methodology (RSM) analysis was performed to establish the reliable Propylene Product Yield model using statistical software, Minitab version 21. RSM is a robust statistical approach that may utilize the available statistical software that is cheaper and practical to be used by Operations personnel at the olefin plant. It is an excellent alternative to the Olefins Licensor’s simulation software that is currently used by the olefin plant worldwide. The analysis of variance (ANOVA) table was utilized to select only significant variables with a p-value of <0.05 for the model. The established final model indicated that Coil Outlet Temperature (COT) was the most important input variable for the Propylene Product Yield generation with a factor of 49.4, compared to -7.76 for Flow of Naphtha, -4.3 for Flow of Integral Burner, 0.292 for Flow of Dilution Steam, and 0.05947 for Flow of Hearth Burner. Besides, the Response Optimizer evaluated that the Propylene Product Yield at the studied SRT VII could be maximized at 13.24% by controlling the process operating parameters with, Flow of Hearth Burner at 9476 kg/hr, Flow of Integral Burner at 609 kg/hr, Flow of Dilution Steam at 40960 kg/hr, Flow of Naphtha at 63.50 t/hr, and COT at 810 °C.