Analysis of pressure behavior during runaway reaction with case studies of various depressurization designs

Abstract

In chemical plants, safety valves are installed on process equipment where pressure rise would occur to prevent their rupture. However, it is difficult to estimate accurate vent size for two-phase flow, and the analysis of pressure rise behavior during a runaway reaction is important. However, ISO method sometimes gives unpractical vent size, therefore, a detailed process dynamic simulation model was constructed in this study. A detailed model was constructed with Aspen and Advanced Reactive System Screening Tool (ARSST) experimental data. The model for depressurization from reactor was the refined omega-method of ISO, which was programmed with Aspen Custom Modeler. The case studies of dynamic simulation are carried out and the result of vent size estimated from ISO method were compared. In addition, some case studies on various process conditions and safety valves such as diameters and set pressures of safety valve, the presence of exhaust gas lines and different solvents were carried out. Different combinations of these conditions produced significantly different behavior in the runaway reaction. Therefore, these results lead to the understanding of runaway reaction and may expect to provide some options for constructing safer processes practicably and economically.