Identification and prediction of inherently safe operating conditions for single diffusion controlled liquid-liquid heterogeneous reactions performed in isoperibolic semibatch reactors

•A new criterion is proposed to identify different thermal behaviors for diffusion controlled liquid–liquid heterogeneous reactions.•A new kind of adiabatic temperature diagram is developed to seek the secondary decomposition reactions.•A series of boundary diagrams and adiabatic temperature diagrams under different operating conditions diagrams are plotted.•A practical procedure is introduced to easily predict the inherently safe operating conditions. It is common that diffusion controlled liquid–liquid heterogeneous reactions are performed in isoperibolic semibatch reactors (SBRs) in chemical and pharmaceutical industries. In this paper dimensionless maximal temperature of the synthesis reactions under cooling failure conditions (MTSR0) and the corresponding dimensionless instant θMTSR vs. jacket temperature profiles for this kind of reactions are thoroughly studied. Based on the variations of MTSR0 and θMTSR a robust criterion to identify different thermal behaviors is introduced. Then a series of boundary diagrams (BDs) and corresponding adiabatic temperature diagrams (ATDs) are plotted. The influences of operating conditions on the shape and location of BDs and ATDs are also investigated. Combining the established BDs and ADTs, the inherently safe operating conditions for this kind of reactions could be easily obtained. Finally a practical procedure is also presented.