Thermal instability and runaway criteria: the dangers of disregarding dynamics

TL;DR

This paper highlights the importance of considering system dynamics in thermal stability analysis, demonstrating that ignoring oscillatory behaviors can lead to dangerous misjudgments of runaway risks in exothermic processes.

Contribution

It shows that stability analyses must include dynamic considerations, revealing oscillatory instabilities missed by steady state assessments in chemical reactors.

Findings

Oscillatory thermal instability can occur without steady state warning signs.

Ignoring dynamics can lead to dangerous underestimation of runaway risks.

Dynamic stability analysis is essential for safe chemical process design.

Abstract

Two exemplary exothermic processes, synthesis of nitroglycerine in a continuous stirred tank reactor (CSTR) and synthesis of the explosive RDX in a CSTR, are used to demonstrate the dangers of ignoring the system dynamics when defining criteria for thermal criticality or runaway. Stability analyses are necessary to prescribe such criteria, and for these systems prove the presence of dangerous oscillatory thermal instability which cannot be detected using the steady state thermal balances.