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Design and Control Studies on the Fluid Catalytic Cracking Process


I. Huq

vol. AUT97-12

Fluid Catalytic Cracking (FCC) units are widely used in the oil refining industry to crack low value hydrocarbons into a range of higher value products including gasoline. Because of its feed processing flexibility, the FCC process is a primary conversion unit in an integrated refinery and optimal FCC operation can have a significant impact on the refinery profitability. Due to this important role in the refinery, the FCC process has recently attracted renewed interest both from academia and industry, with the main emphasis on better understanding and operating the process.

In general, several possible alternatives can usually be postulated or envisioned to realize operational improvements, and the critical task is then to rank order these alternatives. The different alternatives are often analyzed and compared through extensive simulations. In ranking design alternatives through simulation, two crucial factors must be considered if the conclusions are to be reasonably reliable: (1) availability of reliable process models, and (2) tools to reliably quantify the achievable performance with a given alternative in the presence of practically relevant issues such as plant/model mismatch, process constraints, sensor/actuator failures, etc. However, because of stringent environmental and economic requirements, most industrial plants, including the FCC process have evolved into highly complex and integrated processes and ranking alternatives through simulation might be infeasible because of the large number of possible cases that must be considered. This suggests the use of a more efficient, practical approach to ranking alternatives without sacrificing the real life issues such as plant/model mismatch discussed above.

Utilizing two recent first principles dynamic models of the FCC operation and the structured singular value from the area of robust control theory to quantify the achievable performance, several aspects of the design and control of FCC processes are addressed in this thesis, with special emphasis on quantitatively ranking possible design/control/refitting options from the viewpoint of improved operational performance: (1) Design and operational changes to the older Model IV FCC unit to improve the process operation, (2) Optimal control structure selection for FCC regulatory control, (3) The implications and effectiveness of decentralized regulatory control of the FCC process, and (4) Refitting options for heavier feed processing in the FCC unit.


Type of Publication:

(04)Technical Report

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% Autogenerated BibTeX entry
@TechReport { Xxx:1997:IFA_1454,
    author={I. Huq},
    title={{Design and Control Studies on the Fluid Catalytic Cracking
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