Simulação, modelagem e analise de reator de polimerização de eteno em solução usando catalisador Ziegler-Natta / Simulation, modeling and analysis of ethylene polymerization reactor in solution using Ziegler-Natta catalyst

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Polymerization processes are, generally, very complexes due to the high number of parallel reactions and chemical species in reactional medium. Besides, the polymerization reaction engineering may not only attain yield and purity specifications, but also obtain products with certain processability characteristic and final properties that are, in practice, the real measure of performance in polymerization reactors. These properties are determined by operational conditions and reactor employed. By the other side, for good control strategy, optimization and design studies, it is necessary a good process knowledge, what is possible by a mathematic model well suited. Thus, in this study it is developed a phenomenological model for the ethylene with butene-1 polymerization process, in solution with Ziegler-Natta catalyst, in a sequence of PFR (Plug Flow Reactor) and CSTR (Continuous Stirred Tank Reactor) reactors. Simulations from this model evaluate effects of the main process input variables in reactor performance and in polymer properties. Some model parameters, as kinetic constants and some physical properties, for example, are unknown due to scarceness of studies in this area and due to hardness in realizing experiments in a pilot polymerization plant (high temperatures and high pressures). Thus, to obtain quantitative results from the model, it was necessary estimating these unknown parameters from process dynamic data. Polymer end-use properties are usually correlated with mean and polydispersity of MWD (Molecular Weight Distribution). In some situations, however, these properties are influenced by specific molecular weight ranges, thus coming the interest in calculating the whole MWD. Hence, this work develops a new technique, called MWFD (Molecular Weight Fraction Distribution), that allows obtaining the polymer molecular weight fraction distribution. Two models for MWFD calculation were elaborated, one for homopolymerization, the other for copolymerization. In the former, simulations were realized in order to investigate MWD behavior related to main process input variables. But, for the copolymerization, it was elaborated only the theoretical model

ASSUNTO(S)

polymerization reatores quimicos chemical reactors modeling mathematical models polimerização modelagem de dados peso molecular molecular weight modelos matematicos

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