Optimal Grade Transition for Polyethylene Reactors via NCO Tracking
نویسندگان
چکیده
منابع مشابه
Optimal Grade Transition for Polyethylene Reactors via Nco Tracking
I n fluidized-bed gas-phase polymerization reactors, several grades of polyethylene are produced in the same equipment by changing the operating conditions. Transitions between the different grades are rather slow and result in the production of a considerable amount of off-specification polymer. Grade transition improvement is viewed here as a dynamic optimization problem, for which numerous a...
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A study of grade transitions as encountered in polymerization reactors is presented. The results underscore the need for global optimization algorithms to fully realize the benefits of grade transition that are necessarily non-convex. For comparison purposes we use a non-gradient, parallel search, stochastic method, namely differential evolution (DE). Our simulations indicate that while the DE ...
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Gas-phase olefin polymerization fluidized-bed reactors are complex processes that are characterized by large time constants and slow transitions. Optimal grade changes can be computed off-line on the basis of a detailed process model and applied to the process in an open-loop mode. However, the presence of uncertainties in the form of process-model mismatch and disturbances make this approach c...
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A nonlinear control system integrating an off-line optimizer and a nonlinear model-based controller is developed to perform optimal grade transition operations in a continuous pilot plant reactor. A simple black-box model is developed and used to determine optimal trajectories of inputs and outputs for a series of three polypropylene grades. The simplified model is also used to develop a nonlin...
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The use of measurements to compensate the effect of uncertainty has recently gained attention in the context of optimization of dynamic systems. In this field, termed measurement-based optimization, two main categories can be distinguished depending on whether a model of the process or a model of the solution is used for processing the measurements. The former has been studied extensively in th...
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ژورنال
عنوان ژورنال: Chemical Engineering Research and Design
سال: 2005
ISSN: 0263-8762
DOI: 10.1205/cherd.04367