The control of the relative particle growth of a bidisperse emulsion polymerization is investigated in an automated reactor control facility capable of online density and online particle size measurements. Final diame...
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The control of the relative particle growth of a bidisperse emulsion polymerization is investigated in an automated reactor control facility capable of online density and online particle size measurements. Final diameter ratio values are controlled by manipulating the monomer feed rate to the reactor using a control scheme comprised of a parameter adaptive Kalman filter with steady state gains and a nonlinear model predictive controller. One of the main features of the implemented controller is the connection of the prediction horizon to the criterion that the overall conversion equal 90% at the end of the batch. Feedback is incorporated into the algorithm at each sampling time by starting the model prediction calculation at the current estimated values of the model states. The controller performs well to meet a challenging diameter ratio set point at the end of the batch. The robustness of the controller to reject an induced initial initiator concentration disturbance is demonstrated.
The utility of the growth mechanism to influence polystyrene particle size distributions is investigated via a competitive growth framework. A dynamic competitive growth model, extrapolated from an experimentally vali...
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The utility of the growth mechanism to influence polystyrene particle size distributions is investigated via a competitive growth framework. A dynamic competitive growth model, extrapolated from an experimentally validated unimodal model, is used to simulate the semi-batch growth of two monodisperse particle populations at 50°C. Results show that the greatest relative narrowing between the two populations occurs at the particle monomer concentration ([ M ] p ) saturation limit and decreases as [ M ] p is decreased towards a limited reaction lower bound. Simulations run at these limits provide the reachable regions starting from several initial diameter population pairs. The areas of these regions are found to be dependent on the magnitude of the initial diameter ratio and the individual particle sizes.
The tendency modeling approach for optimization, estimation, and control is applied to bioreactors. This approach uses a “tendency” or “grey” model based on the available fundamental knowledge of the process and e...
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The tendency modeling approach for optimization, estimation, and control is applied to bioreactors. This approach uses a “tendency” or “grey” model based on the available fundamental knowledge of the process and emphasizes the incorporation of new process data. The technique is demonstrated on simulation studies and preliminary experimental results of the penicillin fermentation. The tendency model is based on reactor mass balances such as those proposed by Bajpai and Reuß (1980) while the number of overall reactions and their stoichiometry are derived by abstract factor analysis of experimental data. Actual process and equipment constraints, such as the power mounted to the fermentor, the oxygen transfer capacity, and the rheological characteristics of the broth, are added. The model can be updated periodically utilizing data collected both on-line and off-line. The updated model can be used off-line to develop optimal feeding policies. On-line, a Kalman filter can utilize the tendency model to estimate poorly, infrequently, or unmeasured states.
The application of Kalman filtering theory to address the problem of composition control in emulsion copolymerization is investigated. Two different filter designs were implemented carrying out standard state and nois...
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The application of Kalman filtering theory to address the problem of composition control in emulsion copolymerization is investigated. Two different filter designs were implemented carrying out standard state and noise-adaptive state estimation. Satisfactory digital monitoring of the process was obtained with both schemes. The filter estimates were utilized by a deterministic controller regulating the monomer addition rates of the two monomers into a reactor operating in semicontinuous fashion. The quality control strategy was based on a model developed for the vinyl acetate (VAc)/ butyl acrylate (BuA) comonomer system. Real-time experiments demonstrated the efficiency of the approach to minimize drastically the compositional drift.
The steady-state interaction measure of dual composition control schemes for binary distillation columns is examined under the assumptions of constant relative volatility and constant molar overflow. An exhaustive enu...
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The steady-state interaction measure of dual composition control schemes for binary distillation columns is examined under the assumptions of constant relative volatility and constant molar overflow. An exhaustive enumeration is made of the control schemes that use column flows or their ratios as manipulated variables and product compositions as the controlled variables. Using a redundancy criterion, it is shown that 34 classes of dual composition control schemes have independent values for the interaction measure. This number reduces to 17 when the feed is a saturated liquid or gas. For high purity columns, the interaction measure of the above 34 control schemes approaches the values for the (L, V), (D, V), and (L3) control schemes. In this case none of the control schemes has a desirable interaction measure.
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