RUN - Relief of a Runaway Polymerisation Reaction

The manufacture of a polyol lubricant by the condensation of an alcohol with an alkylene oxide in a semi-batch reactor proceeds according to the following 

C4H9OH + (n + 1) C3H6O C4H9 (0C3H6) 0CH2CH0HCH3 -f heat 

The reaction is highly exothermic and the reactor contains large quantities of volatile oxide. Careful control of temperature is therefore required to avoid a runaway reaction and excessive pressure generation. 

The heat removed via the recirculation through the external cooler is given by 

Assuming instantaneous equilibrium, the reactor pressure and oxide vapour pressure is given by  

The simulation emphasises that when reactions start to run away, they do so extremely fast. In this example the rate of pressure generation is compounded by the double exponential terms in the Arrhenius and vapour pressure equations. 

5 Simulation Tools and Examples of Chemical Engineering Processes 

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