Performance improvement and efficiency enhancement of a debutanizer column (a case study in South Pars gas field)

Due to the growing demands for processes such as gas to liquid and steam-methane reforming, in which precious chemicals especially methanol and gasoline are produced, performance enhancement of the debutanizer columns has become the center of attention. Debutanizer column, that is one of the main units of refineries and petrochemical complexes, has the responsibility of separating C4 cuts and lighter components from natural gas liquids, typically gasoline. In this paper, an industrial debutanizer column was simulated applying a steady state flow sheet simulator in order to investigate possible sources of low-efficiency separation problem. In this regards, the reflux ratio and the feed tray location were changed theoretically to achieve higher performance of the column. The results clearly revealed that the 19th tray can be selected as the tray with the best separation performance. Moreover, the optimum reflux ratio was determined and it was proved that better separation can be achieved by applying both modifications simultaneously. In addition, the feedstock liquefaction and the optimum number of liquid furnaces were studied. The results demonstrated that applying three furnaces is more beneficial than one, two or four furnaces and feedstock liquefaction has a slight positive effect on the quality of the separation. In order to investigate whether the application of the optimum reflux ratio and three furnaces can practically improve the separation performance, the aforementioned conditions were subjected to the industrial debutanizer column. The results confirm the improvement of the separation process leading to substantial savings in energy and cost.