OPTIMAL OPERATION OF CRUDE OIL DISTILLATION UNIT
Systematic methods and tools for managing the complexity
Process Control (T4-8)
Keywords: crude unit distillation, control structure selection, optimization
Crude oil distillation is probably the most important process for petrochemical industries because it produces a large number of important products, such as gasoline, naphtha, kerosene, diesel, etc. It is also one of the most complicated operations in any refinery. Crude oil is a complex mixture of hydrocarbons ranging from methane to asphalt, with varying proportions of paraffin, naphthenes, and aromatics. The crude oil distillation unit studied in this paper consists of three main distillation columns: a preflash, an atmospheric crude distillation unit (CDU), and a vacuum distillation unit (VDU). The feed stream is a blend of two different crude oils (50% of each in the normal operation). The mixture is heated in a furnace, where the feed is partially vaporized before entering the bottom of the preflash unit. The preflash unit removes some of the light material in the crude. It does not have a reboiler and live steam is introduced in the bottom of the column. The top product is naphtha and the bottom product is fed into a furnace to be partially vaporized and, afterwards, introduced into the CDU unit. The CDU unit consists of the main column, two pumparounds and three side strippers. Live steam is introduced in the bottom of the column. The column separates into five cuts: heavy naphtha (top product), kerosene, diesel, atmospheric gas oil (AGO), and reduced crude (bottom). The distillate products kerosene, diesel and AGO are withdrawn from the column as side streams. As these products contain material from the adjacent cuts, they are stripped using superheated steam in small side stream stripper columns. The reduced crude is sent to another furnace to be also partially vaporized and fed to the VDU unit. The vacuum tower has, besides the main column, two pumparounds. Live steam is introduced in the bottom and the products of the VDU unit are light vacuum gas oil (LVGO), heavy vacuum gas oil (HVGO) and asphaltic residue. Heavy gas oil is withdrawn as a side stream. The objective of this paper is to obtain an optimal operation point for this system, maximizing the profit, and to select good self-optimizing control structures.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 15:00 to 15:20, in session Process Control (T4-8).
