Polymer Reactors

SIMSCI POLYMER Reactors - Technical Information

The SIMSCI polymer reactor models are able to simulate a free radical, coordination complex, or stepwise bulk or solution polymerization process in an ideal Continuous Stirred Tank Reactor (CSTR) or Plug Flow Reactor (PFR). The reactor type and the desired polymerization processes are specified when the unit is laid down on the Process Flowsheet Diagram (i.e., the PFD).

The polymerization reactions are assumed to take place in the liquid phase and the system is assumed to be homogeneous. The reactors may be run either in isothermal or non-isothermal mode, and the operating pressure may be specified.

The user must supply the feed component temperature, pressure, and composition, along with the operating temperature (for an isothermal reactor) or a temperature estimate (for the non-isothermal reactor). Kinetic and thermodynamic data for the reaction between chemical species also must be provided.

Feeds and Products

Each polymer reactor model allows exactly one (1) feed and one (1) product stream.

Polymerization Process

In free radical polymerization, the polymer component and at least one monomer and one initiator must be specified. The kinetic data supplied for the free radical polymerization must include a minimum of one initiation, one propagation, and one termination mechanism.

In the case of coordination complex polymerization, the polymer component and at least one monomer and one catalyst must be specified. The kinetic data supplied for coordination complex polymerization must include a minimum of one initiation and one propagation mechanism.

For stepwise polymerization, one monomer is specified for Type I or Type III kinetics; two monomers must be specified for Type II kinetics. The kinetic data for the stepwise polymerization must include one chain building (polycondensation or polyaddition) mechanism.

A Short Glossary of Polymerization Terms

Calculation Methods

The SIMSCI free radical polymerization model supports 79 different reaction mechanisms. Not all the mechanisms are intended to be used simultaneously. In fact, the fewer mechanisms specified for the polymer system, the more realistic and reliable the model.

The SIMSCI coordination complex polymerization model supports 22 different reaction mechanisms. Not all the mechanisms are intended to be used simultaneously.

It is assumed that the polymerization reactions occur in the liquid phase. If the reaction leads to a two phase situation, a warning message is given and the user must then specify new operating conditions to keep the system within a single-phase region at all times.

The CSTR mass and energy balances are solved to identify a single stable operating point. The polymer that exists at this operating condition is then characterised in terms of the method of moments to provide number and weight-average molecular weights.

The PFR mass and energy balances are solved to identify a sequence of stable operating points along the reactor’s axial dimension. After the quantity of polymer that exists at each point along this axial profile is computed, it is characterized in terms of the method of moments to provide number and weight-average molecular weights.

Additional information

In this version of PRO/II, the polymer reactor modules are implemented as user-added unit operations provided by SIMSCI. Nonetheless, they are full-featured calculational models. Refer to the Polymers section of the SIMSCI Add-On Modules Users’ Guide for information about preparing the input data. The examples presented there describe all the possible input data. In the 5.11 version of the PRO/II Add-On Modules Users’ Guide, chapter 8 addresses the free radical model, chapter 9 addresses the coordination complex model, and chapter 10 deals with the stepwise polymerization model.

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