"A typical runaway scenario involves reactants being charged into a reactor at room temperature and heated with stirring until the reaction temperature is reached. Temperature is held constant to optimise cycle time and yield. On completion, the reactor is cooled and emptied. However, if no provision is made in the process to account for cooling failure at reaction temperature e.g. due to power failure or operator error (forgot to start the stirrer), etc. then unconverted material still present in the reactor may react at an uncontrollable rate proportional to the amount of unreacted material. This may lead to over-pressure in the vessel and subsequent rupture by virtue of the normal reaction exotherm. Alternatively, a secondary decomposition reaction may be initiated and the heat so produced may lead to yet a further increase in temperature and eventual runaway conditions1 . The prime causes of runaways are associated2,3 with – process chemistry – inadequate design – substandard operational procedures – lack of training – raw-material quality control – temperature control – agitation – mischarging of reactants – maintenance – human factors (which may impact all of the foregoing)".
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