(31f) Optimize until It Hurts

Ethylene and propylene are commodity products and the low-cost producer has the best chance for profitability and long-term success. Cost minimization is part of the equation for being among the low-cost producers. Optimization of process treatments and reuse of by-products are examples of cost reduction. On initial examination, these process changes give the appearance of immediate cost savings. However, the long-term impact of these changes is not always immediately clear, and they need to be studied and understood to ensure that an economic gain will be obtained. This paper discusses four areas where optimization appears attractive, but unanticipated difficulties can and have caused ?self-inflicted? problems that have the potential to offset the apparent gains. These areas are use of compressor wash oils, caustic tower additive treatment, light ends antifoulant optimization and the use of recycle streams as furnace feedstock. Specific examples of the problems in these areas are described.