The UOP Extractive Distillation (ED) Sulfolane process recovers high-purity aromatics from hydrocarbon mixtures by extractive distillation. Extractive Distillation is a lower cost, more suitable option for feeds rich in aromatics containing mostly benzene and/or toluene.
Extractive distillation is used to separate close-boiling components using a solvent that alters the volatility between the components. An ED Sulfolane unit consists of two primary columns; they are the ED column and the solvent recovery column. Aromatic feed is preheated with lean solvent and enters a central stage of the ED column (1). The lean solvent is introduced near the top of the ED column. Nonaromatics are separated from the top of this column and sent to storage.
The ED column bottoms contain solvent and highly purified aromatics that are sent to the solvent recovery column (2). In this column, aromatics are separated from solvent under vacuum with steam stripping. The overhead aromatics product is sent to the BT fractionation section. Lean solvent is separated from the bottom of the column and recirculated back to the ED column.
Economics: The solvent used in the Sulfolane process exhibits higher selectivity and capacity for aromatics than any other commercial solvent. Using the Sulfalane process minimizes concern about trace nitrogen contamination that occurs with nitrogen-based solvents. Estimated inside battery limits (ISBL) costs based on a unit processing 1.12 million metric tpy of BT reformate feedstock with 67 LV% aromatics (US Gulf Coast site in 2010).
Investment, US$ million 29
Utilities (per metric ton of feed)
Electricity, kWh 5.6
Steam, metric ton 0.33
Water, cooling, m3 4.2
Licensor: UOP LLC, A Honeywell Company