Fouling is an ongoing issue in an ethylene plant. During an outage, dirty equipment may be taken out of service for cleaning as needed and deposit samples taken for chemical identification. Often, the chemical identity is already suspected; poly butadiene in the top of the debutanizer or polystyrene in the primary fractionator.
To many plant operators, all foulants are similar and little consideration is given to color, texture, and location of the foulant. One should consider that the foulant is located where it is and looks as it does because temperature, monomer concentration, oxygen, rust, feed rates, feed stocks, feed impurities, and design all impact the why, where, and how of foulant formation. Answering the who, what, where questions provide clues that help to better interpret what is happening in the process and how to tackle the issue. This paper will focus on using these questions to help elucidate foulant formation.