Runaway criteria for predicting the thermal behavior of chemical reactors

Chemical accidents resulting from thermal runaway of chemical reactors can have severe consequences, including catastrophic damages to the public, society, property, and environment. Therefore, it is crucial to develop a methodology that can predict the safety status of reactors and eliminate the potential risk of thermal runaway timely. To this end, various thermal runaway criteria have been established to assess the safety status of reactors over the past decades. This opinion article provides a short review of classic criteria applied to distinguish between runaway and nonrunaway states of reactors. Particularly, the significance of divergence criterion in the field of thermal runaway criteria is emphasized. In addition, to illustrate the general application procedures of the divergence criterion, examples of its utilization in three research domains, including process safety assessment, process parameter optimization, and process monitoring and control, are given. In summary, the remaining challenges and future directions in the development of thermal runaway criteria, especially the divergence criterion, are discussed.