Advanced Control Engineering

The polymerization reactor is usually at the heart of the manufacturing process, impacting both downstream processing and final customer-related polymer properties. The following factors have contributed to the industrial significance of polymer reactor control  

The measurement and control techniques discussed in the previous sections, many of which are generic in nature, are not always adequate to meet the following practical considerations specific to a polymerization reactor, which pose additional challenges to the successful application of a control strategy  

The control system for a polymerization reactor must be sufficiently robust to handle unmeasured disturbances, which impact polymer reactor operation. These disturbances typically result either from trace amounts of polymerization inhibitors left over after monomer purification before the polymerization reaction or from trace amounts of other compounds which may be present in a typical polymerization recipe and which may be affecting the reaction. 

A polymerization reactor often produces several grades (in terms of composition and viscosity) of the same polymer and therefore the control strategy must be easily adapted to a multi-product plant and in some cases to on-line grade transitions. In the case of a multi-product plant it may be necessary to operate the reactor in terms of rather short campaigns in order to noinimize the finished-product inventory and thus the working capital. In these cases the reactor control system must be designed in such a way as to achieve fast startups while minimizing off-specification polymer formation. 

The purpose of this section is to highlight several control engineering techniques, some of which are known in the literature as advanced control , which can be deployed to meet some of the challenging aspects of polymer reactor control. These techniques have been extensively discussed in literature reviews such as 

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