Nonlinear quadratic dynamic matrix control of a fluidized catalytic cracking unit

AUTHOR(S):

TITLE

Nonlinear quadratic dynamic matrix control of a fluidized catalytic cracking unit

ABSTRACT

This paper present the application of a nonlinear model predictive control strategy to an fluidized catalytic cracking (FCC) unit. The FCC is a complex nonlinear process that has been the subject of many models and control studies. The present dynamic model of the FCC process, inspired from Blacken model, uses three lump kinetics to describe the cracking reactions in the riser considered as a plug-flow system. The riser behaviour is described by gasoil, gasoline, coke and energy balances. The separator is considered as a CSTR. The regenerator mainly constituted by a dense and a dilute zone is also considered as a CSTR to represent the catalyst and its dynamic behaviour is described by coke, oxygen and energy balances. This model is sufficiently complex to capture the major dynamic effects that occur in an FCC and to control the key variables that are the riser outlet temperature and the regenerator dense bed temperature. The manipulated inputs are the air inlet flow rate in the regenerator and the regenerated catalyst flow rate. Hard constraints are imposed with respect to the manipulated variables. In spite of the important nonlinearity of the FCC, Nonlinear quadratic dynamic matrix control is able to maintain a smooth multivariable control of the plant, while taking into account the constraints. The comparison study with linear quadratic dynamic matrix control shows a better following of the set point.

KEYWORDS

Nonlinear, Predictive control, fluid catalyst

REFERENCES

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Cite this paper

A.T. Boum, D. Bingong, J.P. Corriou. (2017) Nonlinear quadratic dynamic matrix control of a fluidized catalytic cracking unit. International Journal of Control Systems and Robotics, 2, 141-148