Annals of the Assembly for International Heat Transfer Conference 13
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ARTICLE:
V. Gomes M. Srour ABSTRACT Monitoring and control of monomer conversion is crucial both for proper process operation to reduce downstream separations, and for obtaining products with desired properties. Current techniques to determine conversion such as gravimetry or indirectly through viscosity and density measurements, and gas chromatography, have notable drawbacks. These techniques are implemented off-line, resulting in measurement delay, which is undesirable for real-time control. This work focuses on the development of an alternative approach to conversion monitoring that is suitable for on-line implementation. Polymerization reactions are exothermic in nature, thus temperature profiles and heat flux measurements provide suitable means to monitor the trajectory of the process quite accurately in both industrial and laboratory applications. However, the analysis requires an understanding of the complex physico-chemical processes that occur during polymerization. A dynamic model has been developed to describe calorimetry for emulsion copolymerization of monomers styrene and MMA in batch/semibatch stirred tank reactors. Our model incorporates the complex reaction and reactivity steps of the monomers styrene and MMA. The resulting sets of (differential/algebraic) equations were solved for both species concentrations and temperature profiles as functions of time. Experiments were conducted in a laboratory reactor, instrumented with platinum resistance thermal transducers and gravimetric conversion measurement devices. The model predictions compared well with inferential calorimetric measurements, which were validated using gravimetric data. The experiments were run at variable operational conditions for validation. The calorimetric model was used as a soft sensor for the prediction of the rate of reaction and conversion during the reactor operation. EXP-26 pages |
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