Abstract
The study examines an industrial raffinate distillation column operating as part of an aromatic hydrocarbons recovery unit, for which a persistent deterioration in the sharpness of separation between the desorbent and C8 aromatic components has been observed during operation. Based on the analysis of plant data and steady-state process simulation using the Peng–Robinson equation of state, a comparison between the design and actual operating conditions was performed. It was established that the observed carryover of para-diethylbenzene into the side draw and the contamination of the bottoms product cannot be explained solely by operating parameters. To reproduce the actual temperature profile of the column in the model, it was necessary to reduce the overall tray efficiency in the upper section of the column to 17% (Murphree efficiency), indicating the presence of hydrodynamic disturbances and a decrease in the effective mass-transfer performance of the contacting devices. The product quality was shown to be highly sensitive to the combined variation of column pressure and reflux temperature, particularly under conditions of limited heat removal capacity during summer operation. The results demonstrate the need to reassess the condition of the internal contacting devices and substantiate the feasibility of hardware modernization of the column as a means of improving process stability and efficiency.