Jet fires and reaction runaway interaction: A multiscale approach

In industrial safety, large engulfing jet fires can cause damages and collapse of process vessels with catastrophic consequences; however, even smaller jet fires can be extremely dangerous due to their ability to induce hazardous conditions when chemical reacting systems are involved. This work investigates the ethoxylation of 1-dodecanol as a case-study to investigate the potentialities of a multiscale approach able to analyse scenarios of accidental impingement on a chemical reactor involving a jet fire. In particular, the investigated system was a Venturi tower reactor, where the reacting fluid is pumped, cooled via an external heat exchanger and sprayed from the top of the reactor together with ethylene oxide. The aim is to understand if and when the cooling power of the external heat exchanger can prevent dangerous temperature build-up in the chemical reactor. The multiscale approach used in this work involves a series of mathematical simulations aimed at evaluating the effects of different jet fires in terms of heat flux entering the Venturi reactor impinged by a jet fire. These simulations were carried out using a mathematical model developed in the framework of computational fluid dynamics (CFD). The results of such simulations were used to carry out a parametric study with a 0D model able to foresee the dynamic behaviour of the reactor impinged by the jet fire. Preliminary results confirmed the possibility of linking jet fires characteristics with the time available before dangerous conditions in the Venturi reactor occur, therefore allowing for making an estimation of the time available for activating proper mitigation measures.