Recovery of Value Added Products Can Help Survival of Solvent Extraction Unites in a Lube Processing Refinery: A Case Study

摘要

In a refinery, crude petroleum oil is distilled in an atmospheric column to separate fuel gases and distillates. Reduced crude oil (RCO) from the atmospheric distillation unit is further distilled under a vacuum, yielding varieties of distillates like vacuum gas oil and light to heavy viscous distillates. In a typical lubricating base oil-producing refinery, viscous distillates from intermediate to heavy are available from such a unit. Highly viscous distillate is also recovered from the vacuum residue. Solvent extraction takes place (Sequeira and Dekker, 1993c, p. 81; 1993b, p. 153) next to selectively dearomatize the distillates to yield high viscosity index (VI) oil. In order for the pour point to be improved, selective removal of paraffin wax is carried out in a solvent dewaxing unit. Finally this dewaxed oil is selectively hydrogenated to remove unwanted sulfur, nitrogen, and oxygen and also for improving color. Though modern catalytic aromatic saturation and dewaxing (Sequeira and Dekker, 1993a, p. 194; Raseev, 2003, p. 674) are replacing the traditional solvent refining processes, valuable products like wax, carbon black, and bitumen are available only from solvent refining processes. A typical solvent extraction unit has been studied for enhancing quality and quantity of value-added products like lube base stock, wax, carbon black feed stock (CBFS) and bitumen.