Reflux Temperature Control – A Case Study

FRI’s reflux heater is required to operate over a wide range of test conditions – typically, operating pressures from vacuum to 500 psia with 3 hydrocarbon systems. At some conditions, reflux temperature control by manipulating the steam condensate level in the shell was inadequate. A new control strategy to manipulate the inlet steam pressure instead of the steam condensate level provided improved control performance and the ability to operate effectively at various duties. Additional benefits in column control were also realized. In this paper, the new control strategy, its implementation, and performance improvements are discussed.