Control of polymerization reactors

The operation of polymerization reactors is very complex for a number of reasons. 

For all the reasons presented above, research and technical activities are very intense and diversified in the field of polymerization reactor control, so that no sort of general control solution can be provided without taking into consideration the particular characteristics of the analyzed polymerization system [3]. 

The scenario described in the previous paragraphs probably explains the large number of surveys that have been published in the open literature about the control of polymerization reactors. Therefore, the main objective of this chapter is not reviewing the whole field of polymerization reactor control, but presenting the main features and discussing the main trends of the area [3]. Illustrative examples are selected among the many publications in the field. Detailed presentation and analysis of the different proposed control approaches [4-10] and of the distinct used monitoring techniques [11-14] can be found in the available surveys. 

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F.J. Schork, R.B. Deshpander, and K.W. Leffew. Control of Polymerization Reactors. Marcel Dekker, New York, 1993. 

Santos AF, Silva FM, Lenzi MK, Pinto JC. Monitoring and control of polymerization reactors using NIR spectroscopy. Polymer-Plastics Technology and Engineering 2005,44, 1-61. 

Suffice it to say that the control of polymerization reactors is a most challenging and complex problem. 

The quantitative relationship between these product quality parameters and reactor operating conditions may be the least understood area of polymerization reaction engineering. Table VI summarizes both types of quality control measures. Because of the lack of on-line measurements for most of these product quality variables (molecular or otherwise), control of polymerization reactors is a special challenge. 

E. J. Schorlc, P, B, Deshpande, K. W, Leffew, Control of Polymerization Reactor. New York Marcel Dekker (1993). 

A comprehensive review of the broad aspects of polymerization process modeling and its applications is not the objective here. In this entry, some critical issues related to the modeling, design, and control of polymerization reactors are discussed with some examples to illustrate modeling techniques and their applications to polymerization process optimization and control. 

Schork, F.J. Deshpande, P.B. Leffew, K.W. Control of Polymerization Reactors Marcel Dekker New York, 1993. 

Forty years ago these computed variables were calculated using pneumatic devices. Today they are much more easily done in the digital control computer. Much more complex types of computed variables can now be calculated. Several variables of a process can be measured, and all the other variables can be calculated from a rigorous model of the process. For example, the nearness to flooding in distillation columns can be calculated from heat input, feed flow rate, and temperature and pressure data. Another application is the calculation of product purities in a distillation column from measurements of several tray temperatures and flow rates by the use of mass and energy balances, physical property data, and vapor-liquid equilibrium information. Successful applications have been reported in the control of polymerization reactors. 

The important problems include the control of polymerization reactors containing rheokinetic liquids. These problems have not been solved in many respects even for more simple situations. Both mathematical modelling and physical understanding of the process are the key problems [112]. 

The production of polyolefins by means of coordination polymerization, which is the highest tonnage polymerization process, is discussed first. The following chapters present the production of polymers by free-radical polymerization in homogeneous, heterogeneous and dispersed (suspension and emulsion) media. Afterwards, the reaction engineering of step-growth polymerization is discussed. The last chapter is devoted to the control of polymerization reactors. 

This can be seen in the simulation of the PID control of polymerization reactor temperature by Houston and Schork [34]. Reactor temperature is often controlled by manipulating the temperature or flow rate of coolant in the reactor cooling jacket. This scheme is hindered by the slow dynamics of heat removal and the nonlinear nature of the heat evolution process (especially in... 

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