Catalytic cracking models developed for predictive control purposes

• Published in: Modeling, identification and control Vol. 14; no. 2; pp. 73 - 84
• Main Authors: LJUNGQUIST, D, STRAND, S, BALCHEN, J. G
• Format: Journal Article
• Language: English
• Published: Oslo Research Council of Norway 01.04.1993; Norsk Forening for Automatisering (NFA); Norwegian Society of Automatic Control
• Subjects: Applied sciences; catalytic cracking; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; modeling; predictive control; Processing of crude oil and oils from shales and tar sands. Processes. Equipment. Refinery and treatment units; State-space methods; State space method; Refining; Linear model; Optimization method; Catalytic cracking
• ISSN: 0332-7353; 1890-1328
• DOI: 10.4173/mic.1993.2.2

The paper deals with state-space modeling issues in the context of model-predictive control, with application to catalytic cracking. Emphasis is placed on model establishment, verification and online adjustment. Both the Fluid Catalytic Cracking (FCC) and the Residual Catalytic Cracking (RCC) units are discussed. Catalytic cracking units involve complex interactive processes which are difficult to operate and control in an economically optimal way. The strong nonlinearities of the FCC process mean that the control calculation should be based on a nonlinear model with the relevant constraints included. However, the model can be simple compared to the complexity of the catalytic cracking plant. Model validity is ensured by a robust online model adjustment strategy. Model-predictive control schemes based on linear convolution models have been successfully applied to the supervisory dynamic control of catalytic cracking units, and the control can be further improved by the SSPC scheme.