We use multivariable feedback control to reduce variations in flow and back-pressure associated with two industrial separator units forming part of an edible oil refining line. This provides plant operators with a mechanism for increasing process yield without reducing product quality. Actuator limits are a natural consideration in the controller design since increased production rates require actuators to operate on or near their limits. We use recentred barrier function model predictive control in this application and obtain favourable results. (C) 2004 Elsevier Ltd. All rights reserved.