Advanced controls improve operation of lubes plant dewaxing unit

BP Oil`s 115,000 b/d refinery at Kwinana, Western Australia, recently installed a multivariable, predictive controller in the methyl ethyl ketone (MEK) dewaxing unit in its lubes plant. Benefits of the control system include: stable operation of the MEK dewaxing unit; reduced time required by operators for solvent management; reduced occurrences of process upsets resulting from contamination of dry solvent; and savings of $375,000/year, resulting in a project payback of less than 5 months. The paper describes the process, control requirements, control design, implementation and process improvements.