Study of the initiator mischarging effect on runaway reaction of styrene polymerization
Additional Document Info
(2019) by AIChE. All rights reserved. Polymerization reactions are prone to runaway risks due to the unstable nature of monomers and complex exothermic interactions between reactants. Deviation from a normal recipe or designed operation condition may lead to auto-accelerated temperature and pressure rise, followed by rupture of reaction vessels, fire, and explosion. Mischarging of initiators (radical generators) is one of the most common credible mal-operation cases, which has only been studied to a limited extend. In this study, benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as initiators for styrene polymerization as a function of high concentrations to mimic the mischarging scenarios. Both screening and adiabatic tests were performed to obtain the most critical safety parameters such as onset temperature, adiabatic temperature rise, and time to maximum rate. It was found that there exists a significant difference in reaction pathways and safety indicators with respect to initiator type and concentration. Uncontrolled initiation reactions not only lead to subsequent faster polymerization but also pose threats to relief valve design due to the generation of non-condensable gas. We anticipate that this study will provide beneficial guidelines for polymer manufacturers on the initiator selection and also thermal runaway prevention.