The chemical industry is highly prone to the risks associated with thermal runaway reactions. When the rate of heat generation exceeds the rate of cooling, the reaction is no longer stable and a runaway reaction may occur. This runaway reaction is characterized by a rapid increase in temperature and pressure due to the boiling of the contents and vapor and/or gas generation over a short period of time. The pressure and temperature increase may lead to fires, explosions among with many incurred damages as was the case in Bhopal and Seveso.
Chemical systems under runaway conditions can be classified in two types: tempered and untempered systems. For tempered systems, the pressure generation in the vessel is mainly due to the production of vapor and the control of the pressure of the reactor vessel via the activation of a properly sized emergency relief system allows the control of the temperature of the reactive mixture and therefore the reaction kinetics. For untempered systems the pressure increase is due to the production of non-condensable gases and the depressurization of the vessel does not affect the reaction kinetics.
Several challenges are associated with the experimental determination of the gas production rate of following runaway reaction of untempered systems for pressure relief vent sizing calculation. In the study being conducted, the runaway reaction of an untempered systems (cumene hydroperoxide in diisobutyrate solvent) is investigated at laboratory scale using a low-phi adiabatic calorimeter. The experimental data are analyzed to assess the maximum gas generation rate. The effect of the experimental conditions with the adiabatic calorimeter on the measured maximum gas generation rate are discussed.
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