Putting on the Brakes: Potential Pitfalls of Unit Turndowns and How to Avoid Them

Whether dictated by adverse market conditions, plant constraints, equipment failure, inclement weather, or other considerations, often chemical manufacturers need to reduce production rates or even shut down the unit altogether. In an ethylene plant, unit turndown or shutdown can have significant impacts in nearly every area of the facility, from the quench to light ends fractionation. Many of these impacts can negatively affect operation due to increased potential for fouling, corrosion, emulsions, and foaming in distillation towers, heat exchangers, and other equipment and piping.

The purpose of this paper is to examine a selection of the most common, treacherous pitfalls that can occur during turndown and shutdown to determine what the impacts can be and how to mitigate them from a mechanical, operational, and chemical standpoint, thus providing for safer, more reliable operation and the protection of valuable assets.