ABSTRACT
Complexity factors were introduced by Wilbur Nelson in the 1960s to compare two refineries relative to their sophistication and capital intensity. The chapter begins by defining an ideal refinery and introducing complexity factors, complexity cross factors, and methodologies used in their assessment. Complexity factors were introduced to quantify and simplify classification so that refineries could be compared using one statistic that reflects their sophistication and capital intensity. Complexity factors are normalized with respect to atmospheric distillation since distillation is usually the cheapest process to build and has the greatest throughput capacity. The traditional way to compute complexity factors is to apply Nelson’s definition directly to adjusted and normalized cost data. Refinery complexity quantifies the type of process units in a refinery and their capacity relative to atmospheric distillation. By using cost functions, a more precise and transparent formulation of complexity factor emerges, and the chapter concludes with a functional formulation of complexity factor.
