Reactor with dead polymer model

Calculated Molecular Weight Distributions. The calculated weight fraction distributions for the micro-mixed, segregated, and micro-mixed reactor with dead-polymer models for Runs 2, 5,... 

The micro-mixed reactor with dead-polymer model was developed to account for the large values of the polydispersity index observed experimentally. The effect of increasing the fraction of dead-polymer in the reactor feed while maintaining the same monomer conversion is to broaden the product polymer distribution and therefore to increase the polydispersity index. As illustrated in Table V, this model, with its adjustable parameter, can exactly match experiment average molecular weights and easily account for values of the polydispersity index significantly greater than 2. 

The micro-mixed reactor with dead-polymer model simulated the product of the laboratory reactor well within experimental accuracy. 

To differentiate between the micro-mixed reactor with dead-polymer and the by-pass reactor models in this investigation, the effect of mixing speed on the value of "( )" was observed. As illustrated in Table V, the value (j>" is not observed to increase with decreasing mixing speed as would be expected for a by-pass reactor. This rules out the possibility of a by-pass model and further substantiates the dead-polymer model. 

In some situations where one or more of the latex properties are measured either directly or indirectly through their correlation with surrogate variables and where extreme nonlinearities such as the periodic generation of polymer particles does not occur, one can use much simpler modehng and control techniques. Linear transfer function-type models can he identified directly from the plant reactor data. Conventional control devices such as PID controllers or PID controllers with dead-time compensation can then be designed. If process data is also used to identify... 

Free-radical high-pressure LDPE tubular reactors can be modelled in terms of a system of non-linear differential equations. Over the past twenty years, several modelling studies have been reported in the literature (Thies and Schoenemann I 1Agrawal and Han I 2j, Chen et al. 1 3H, Thies 1 4], Lee and Marano l5J, Donati et al. 1 6J, Goto et al. 7J, Yoon and Rhee [ S y Gupta et al. 9 ). In the present work, a detailed mathematical model is developed for an LDPE tubular reactor. The variation of the physical properties of the reaction mixture with position is accounted for. The elements of the model are the reaction mechanism, the mass, energy and momentum balances, and the moments of live and dead polymer distributions. Polyethylene is produced via the following set of elementary reactions k. 

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