Assessment of the maximum gas generation rate of a gas generating system under runaway conditions Conference Paper uri icon


  • 2017 IChemE. Runaway reactions are characterized by the exponential increase of the temperature of an exothermic chemical reaction as well as the pressure of the reactor or storage vessel in which the runaway occurs. The consequences of a runaway reaction can be catastrophic as it can lead to the overpressurization of a vessel and its potential explosion. Emergency relief systems (ERS) can act as the last line of defense against vessel overpressure and prevent the vessel explosion, providing they are adequately sized. In the case of the runaway of gas producing chemical systems (gassy or hybrid reactive systems), the assessment of the maximum gas generation rate under runaway conditions is a critical parameter for sizing an ERS. In the 1980's the Design Institute of Emergency Relief System (DIERS) developed experimental methods to assess the maximum for gas generation rate for runaway reaction based on adiabatic calorimetry data (mainly temperature and pressure measurement under adiabatic runaway conditions). There is still need to improve such methods in the particular case of gas generating systems. Indeed, there's currently no consensus in the industry as per the best configuration (close or open cell) of the adiabatic test for the study of gas generating systems nor the interpretation of the experimental data for the assessment of the maximum gas generation rate. This paper performs a critical analysis of the current method to assess the maximum gas generation rate of a gas generating system under runaway condition. It presents the results of the modeling of the decomposition of a solution of 20% Di-tert-butyl Peroxide (DTBP) in Toluene in a closed vessel using a rigorous thermodynamic evaluation of component and mixtures properties coupled with the kinetic model of the decomposition reaction. The model is able to accurately evaluate the composition of the liquid and gas phases in the calorimetric cell at each time step of the runaway. The simulation results are used to evaluate the ability of the current method proposed by the DIERS (based on the evaluation of the gas generation from temperature and pressure data and the ideal gas law) to assess the actual maximum specific gas generation rate inside the calorimetric cell during the runaway. The simulation results highlighted that the general approach assuming that the sole use of the temperature and pressure readings of a calorimetric test cell to calculate the maximum gas generation rate is limited and needs significant improvements.

published proceedings

  • Institution of Chemical Engineers Symposium Series

author list (cited authors)

  • Saha, N., Castier, M., Kanes, R., & Vchot, L.

complete list of authors

  • Saha, N||Castier, M||Kanes, R||VĂ©chot, L