Exergy Analysis and Optimization of Crude Distilllation Unit(CDU) of a Refinery.
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Date
2016
Authors
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Publisher
Obafemi Awolowo University
Abstract
This study carried out steady state simulation of the Crude distillation unit of a refinery. The exergy analysis of each process vessel in the crude distillation unit (CDU) of the refinery was performed. The parametric study and optimization of the crude distillation column was done by combining operating parameters that have significant effects on Irreversibility and exergy efficiency of the crude distillation column. This was with a view to identifying the operating conditions for the optimum performance for the column.
The simulation of the process was done by using Hyprotech System Simulator (HYSYS) version 8.4 developed by Aspen Technology with Peng Robinson Equation of State (EOS). In addition, a three level Box-Behnken experimental design and quadratic response surface model were used to optimize the exergy efficiency of the unit using Minitab 16. The quadratic model was examined in terms of the goodness of fit and the analysis of variance (ANOVA) at 95% confidence interval was used to evaluate the adequacy of the fitted quadratic model.
The results of the base case irreversibility and exergy efficiency of the investigated crude distillation column were 134.6 MW and 74.6% respectively. The exergy efficiency and irreversibility of the control volume were found to be 427.0 MW and 48.07%. The mixer, phase separator and the distillation unit are the largest contributors to the overall irreversibility. The statistical model predicted an optimum exergy efficiency of 95.6% for the combinations of Heated crude pressure of 513.6 kPa, heated crude temperature of 182 oC , and hot crude temperature of 353 oC; and Heated crude pressure of 513.6 kPa, heated crude temperature of 182 oC, and condenser pressure of 121 kPa for the crude distillation column. The exergy efficiencies of the process vessels were calculated to be 71.3%, 71.6%, 22.8%, 75.6%, 88.8%, 38.5% and 46.3% for the mixer, phase separator, Heater 1, pre-flash drum, pump, Heater 2 and, furnace respectively.
The study concluded that optimization of the crude distillation column was necessary for better performance, improved and increased yield. It was also established that variations in the process parameters of other process vessels like the preflash drum, and the furnace directly affects the performance of the crude distillation column.
Description
xv,125 P
Keywords
Exergy Anylysis, Crude Oil, Refinery, Hyprotech System, Aspen Technology, Peng Robinson Equation of State
Citation
David,O.S(2016).Exergy analysis and optimization of Crude distilllation unit(CDU) of a refinery.