Integration of Nonlinear Crude Distillation Unit Models in Refinery Planning Optimization

• Published in: Industrial & engineering chemistry research Vol. 50; no. 11; pp. 6860 - 6870
• Main Authors: Alattas, Abdulrahman M., Grossmann, Ignacio E., Palou-Rivera, Ignasi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.06.2011
• Subjects: Applied sciences; Chemical engineering; Distillation; Exact sciences and technology; Process Design and Control; Distillation; Planning; Refinery; Modeling; Optimization
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie200151e

Production planning modeling is an essential tool in the operation and management of modern refineries. It has traditionally relied on linear programming (LP) principles and methods for simple and robust planning models, such as the fixed-yield planning models and swing cuts planning models. However, these models fail to reflect the true nonlinear nature of the processing units. In this work, the fractionation index model (FI) is developed to add nonlinearity to the linear refinery planning models. The FI model is developed as a more accurate nonlinear model for the complex crude distillation unit (CDU) than the fixed yield or the swing cuts models. The resulting simple model optimizes the crude cuts quantities and temperature. It has the benefits of being crude independent, characteristics of the CDU, and readily calculated. An example of the FI CDU model is presented. The FI-based refinery planning model is then developed and tested with a refinery planning example. The results are compared to the common fixed yield and swing cuts models. The FI refinery planning model predicted higher profit based on different crude purchase decision. Despite an order of magnitude increase in the problem size, the FI planning model did not require significantly longer solution times.