A control system for a fractionation column which separates a feed into a heavy bottoms product, which is used as fuel for a plant, and into a light overhead product, which is used in a process, is disclosed. The fractionation column is controlled in such a manner that sufficient bottoms product is supplied to meet the plant fuel requirements while maintaining a desired distillation temperature for the overhead product. The flow rate of fuel oil to the reboiler furnace associated with the fractionation column and the flow rate of the external reflux to the fractionation column are controlled in such a manner that the objectives of supplying sufficient bottoms product to meet plant fuel requirements and supplying an overhead product having a desired distillation temperature are met while still minimizing the external reflux flow rate and the flow rate of the fuel oil to the reboiler furnace to increase fuel economy.