Energy Conservation in Distillation

John Pendergast, Dow Chemical Company (Retired)

Dennis Jewell, Dow Chemical Company

David Vickery, Dow Chemical Company

Jose Bravo, Fractionation Research Inc.

Separations operations account for roughly 50 to 70% of the energy and the capital in the large scale Chemical Process Industries (CPI) ⁽¹⁾. Not surprisingly, along with the consumption of the energy, separation processes also account for the same fraction of the capital required for the processes. By far the dominant unit operation utilized for these separations is distillation, along with the related operations of absorption and stripping*. This fact was recently brought out again in the widely read and highly regarded publication Nature by David Scholl and Ron Lively. ⁽²⁾ Lively and Scholl describe important separations that, if the separation could be performed in a more energy manner, could have worldwide impact. In this article, we briefly discuss some of the reasons that progress in energy conservation seems sometimes to be slow, and then we present ideas that have proven useful in reducing energy consumption in existing facilities.