Discovery of operational spaces from process data for production of multiple grades of products

An industrial case study is presented which uses principal component analysis (PCA) to identify operational spaces and develop operational strategies for manufacturing desired products. Analysis of a historical database of 303 data cases from a refinery fluid catalytic cracking process discovered that the data are projected to four operational zones in the reduced two-dimensional plane. Three zones were found to correspond to three different product grades, and the fourth is a zone that has a high probability of product off-specification and is very likely caused by product changeover. Variable contribution analysis was also conducted to identify the most important variables that are responsible for the observed operational spaces, and consequently strategies were developed for monitoring and operating the process in order to be able to move the operation from producing one product grade to another, with minimum time delays.