Steady states analysis and dynamic simulation as a complement in the HAZOP study of chemical reactors

This paper discusses the relation between software tools primarily designed for mathematical modelling, simulation and investigation of chemical reactors and the common method for identification of hazard, the Hazard and Operability (HAZOP) study. We have tried to couple these tools with the HAZOP study. The principal objective was to present a new methodology for hazard investigation. In our work a multi-parameter analysis of a model system with exothermic reaction (hydrolysis of propylene oxide to mono-propylene glycol with consecutive reactions producing higher glycols) in two continuous-stirred tank reactors (CSTRs) in series with jacket cooling was used. In the first section a mathematical model of two CSTRs in series was formulated. The next step is safety analysis, including analysis of the multiplicity of steady states and their stability, study of safe operating, and conditions and trajectories, which can shift the reactors from one steady state to another steady state. Parametric studies of the failure of the reactants flow rate (propylene oxide and water) and of the cooling medium were also done. Finally, the results of safety analysis were reproduced and we tried to find all possibilities for utilization of these results in HAZOP studies.