It has always been fundamental for refiners to keep the FCCU running in a profitable operating mode, but lately this task has turned even more challenging due to new market conditions and environmental restrictions. One approach to maximize profitability is to process “opportunity” feeds. While this approach can potentially improve the cracking margin, it also brings new challenges of its own by pushing the FCCU operation against new constraints. The choice of FCCU catalyst is a very important factor when processing opportunity feeds. Catalyst suppliers have tried many different approaches to optimize formulations and technology to help the refiners reach their goals. Several such approaches, including optimizing catalyst accessibility (mass transfer) and synergies between catalyst components, are discussed in this paper. In addition, a broad overview of the FCCU world is presented by analyzing an extensive database of equilibrium catalysts and summarizing commercial results from a significant number of FCCU units. Many interesting and perhaps surprising conclusions are drawn. Several traditional myths or “absolute truths” about FCCU operations and catalysts do not survive when checked against real data and facts. Ideas like: “the higher the catalyst surface area the better”, or “just add enough alumina and you get the bottoms conversion you need”, or “you need to buy a catalyst with a metals trap to crack heavy feeds” do not hold up to a comprehensive analysis of the data. Ideas such as these are examined in this paper. However, first an introduction to opportunity feeds is presented.
展开▼
