Large-scale distillation towers use a reflux system to achieve a more complete product separation. Reflux is that portion of a tower’s condensed overhead liquid product that is cycled back to the top of the tower where it flows downward to provide cooling and condensation of the upflowing vapors.
The reflux drum, or accumulator, serves as a distribution point for reflux and distillate. Condensed liquid leaves the reflux drum under level control. Drum level control is critical to ensure that the proper amount of reflux will return to the distillation tower. Poor liquid level indication can cause expensive operating problems and product degradation.