Increasing the reactant conversion through induced oscillations in a continuous stirred tank reactor by using PI control

• Complete model of a PI controlled CSTR to research its self-oscillating behavior.
• Incorporation of two PI controllers to produce sustained oscillations.
• Determination of cusp point and lobe curves as a function of the PI parameters.
• Reactant conversion increment through oscillations generated by the PI controllers.
• Graphics to choose the PI controller parameters to analyze the reactant conversion.

We report a strategy to increase the reactant conversion in a continuous stirred tank reactor (CSTR) to produce propylene glycol through induced oscillations generated by two controllers PI1 and PI2 that manipulate the reactor outlet flow and the coolant flow rate respectively. It is shown that an adequate parameter choice for the PI controllers allows one to derive sustained oscillations in the concentrations and reactor temperature, which in turn allows increasing the propylene glycol production. For a suitable choice of the PI1 and PI2 controller parameters, we use a complete reactor model that provides with physically feasible parameters. The issues of external disturbance rejection, self-oscillations and stability have also been discussed. The analytical calculations are verified by means of full numerical simulations.