Alkylation Process Design

Project goal: To design an alkylation unit that produces 5,000 barrels of alkylate per day from a common olefin feedstock found in oil-processing plants. This process converts light hydrocarbons (four-carbon chains)to a heavier hydrocarbon (eight-carbon chain), which is a preferred stock for blending high-octane gasoline to be used in airplanes and automobiles. The reactor and auxiliary units are to be placed in an existing refinery, so footprint and safety requirements are considered in the design. Sulfuric acid is used as a catalyst to run the process at reasonable operating conditions for a large-scale plant. Hydrofluoric acid can also be used, so a cost and safety comparison between the two was conducted. The first reactant for this process, butylene, is commonly created in the separation of crude oil. Typically, lighter hydrocarbons are unusable in fuel blending due to their low boiling point, so heavier molecules are created to output a higher quantity of valuable product from the refinery. By reacting butylene with isobutane via a sulfuric acid catalyst, the two molecules combine to form an eight-carbon hydrocarbon generally referred to as octane, which is sent to a different area of the plant for blending into a variety of fuels. Most of this process was simulated in Aspen Plus software and checked against best industry practices. The project also analyzed and accounted for economics, safety,and environmental impact.