Nonlinear Geometric Temperature Control of a Vinyl Acetate Emulsion Polymerization Reactor

In
this paper, an industrial emulsion polymerization process, which
is characterized by exothermic reactions with complex nonlinear dynamics,
is addressed. In this process vinyl acetate is used as monomer, potassium
persulfate as initiator and polyvinyl alcohol as protective colloid.
A model of the system to calculate average molecular weight and dispersity
is implemented. A fine and strict temperature control is required
in order to guarantee the product quality and safe operation. Nonlinear
geometric control based on input/output linearization is used for
reactor temperature control. An extended Kalman filter is implemented
to estimate unmeasured states. Performance tests of the controller
and state estimator are carried out by introducing modeling and estimator
errors. It is also verified that the nonlinear controller can work
with different initiator feed policies helping to improve the process
productivity. Finally, compared to a traditional PID controller, the
nonlinear geometric controller is superior in rejecting disturbances
and performing set point tracking.