(35b) Troubleshooting Fouling with a Deposit's Color, Texture, Location

After mechanical issues, fouling is generally the second or third cause of pre-mature shut downs in primary olefin units ¹.

Although fouling occurs in many different locations in the plant, the foulant typically is one of only a handful of chemical components: polystyrene, pytar, polybutadiene, aldol polymer, and combinations thereof.

What is often overlooked when analyzing polymer is why it is where it is and why it looks like it does. This paper will focus on some of these polymers’ physical (not chemical) appearances and locations and how this information can be interpreted and used to control fouling. (Chemical treatment programs will NOT be discussed). For example, foulant pieces at a feed point suggests deposition from the tower upstream. Light, porous foulant suggests it was liquid when it cooled and full of gas, which caused the polymer to “puff up” while cooling. Polymer in the underside of a tray suggests vapor space fouling. Once the chemical and physical properties of the foulant are properly identified, a comprehensive approach can be developed to address the fouling.

1. Cagnolatti, C. L. HSB Solomon Associates, LLC

Hydrocarbon Processing April 2015, pg. 31-36