Runaway Potential and Pressure Rise in the Polymerization of Styrene-Butadiene

Abstract

The safe operation of the batch emulsion polymerization of Styrene-Butadiene, with all reactants charged at the start, is studied. In order to assess runaway potential, simplified kinetic and headspace pressure models are developed. Kinetic information is obtained from isothermal reaction runs carried out over wide ranges of temperature (70 to 125'C) and pressures (8 to 23 bars). Detailed experimental setups and methods for both Butadiene distillation and reactor operation, are given for an industrial polymerization recipe. Simulation studies based on numerical integration of the heat and mass balance equations for cooled reactors show that for the relatively large particle size latex of this study, the reactor is not parametrically sensitive. The influence on the scaleup of the various heat transfer parameters, is discussed.

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“…The larger the reactor vessel, the larger the volume occupied by the liquid mixture. However, the available heat transfer area will be increased more slowly than the volume, so that the nominal ratio A / V decreases with the scale of operation 34. To summarize the vessel size effects, a parameter designated the characteristic cooling time ( C R ) is introduced, defined as the cooling time relative to the feed time: …”

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“…For an adiabatic reaction N ϭ 0, the cooling intensity N decreases for vessels of increasing size, so that this quantity can be used to rank reactor vessel sizes. 34 After solving the system of equations it is possible to know the temperature of the reacting mixture and both the conversion and the accumulation of unreacted species. The accumulation ␣ is defined as the moles of B remaining relative to the moles of A initially charged.…”

“…However, the available heat transfer area will be increased more slowly than the volume, so that the nominal ratio A/V decreases with the scale of operation. 34 To summarize the vessel size effects, a parameter designated the characteristic cooling time (C R ) is introduced, defined as the cooling time relative to the feed time:…”