A crude distillation unit (CDU) is central to an oil refinery. Refiners face numerous challenges affecting their businesses. Volatile crude oil prices and changing environmental regulations add up to the size and complexity of the problem. Equipment breakdown has become a normal routine in the day-to-day refinery operations. These scenarios call for the need of plant optimization to improve revenues and to reduce operational costs simultaneously. A systematic method involving selection of the significant process variables is a way forward to tackle this problem. Taguchi and response surface methods are two of the many examples of parametric design techniques that can be used for this purpose. This book discusses the utilization of these methods in CDU optimization.