The Evolution of Light Ends Fractionation Fouling Control: From Mechanism to Mitigation, Three Decades of Dramatic Improvement

The Evolution of Light Ends Fractionation Fouling Control: From Mechanism to Mitigation, Three Decades of Dramatic Improvement

M. David Smith

Nalco Champion, an Ecolab Company

In the 1980s, the average run length for an ethylene plant between turnarounds was only around 18 months, as severe polymer formation in the product fractionation area caused premature equipment failures, excessive cleaning and disposal costs, and capacity restrictions. The industry response was multi-faceted. From a design standpoint, equipment was designed for less fouling severity and to be more easily taken off-line for cleaning and repair without sacrificing production. Innovations in equipment arrangement and metallurgy also helped improve reliability. Additionally, the chemistry mechanism for polymerization was studied, and chemical additives were developed to mitigate fouling and improve reliability and production.

The result of these innovations was dramatic improvement: ethylene plant run lengths extended from 18 months to several years, with some plants running up to 10 years without the light ends fractionation equipment becoming a plant restriction.

This paper discusses the mechanisms of polymerization in the light ends fractionation area and some of the innovations over the past three decades that have produced this revolutionary advance in ethylene plant operations reliability. Further, the paper takes a forward-looking view to the impacts of shale gas, new grassroots construction, site expansion, and other changes moving forward from a Mechanical, Operational, and Chemical standpoint.