Combustion Science and Technology, Vol.138, No.1-6, 159-177, 1998
Predictive method of pressure venting for dust explosions in large vessels
A simple modelling easily usable in the industrial environment has been previously described in order to predict the evolution of the combustion characteristics of solid-gas mixtures in a closed vessel. The aim of this work consists in extending the model development to a wide range of dust suspensions in the general case of vented explosions and to test. the model behaviour to get a risk evaluation and improve safety conditions in industrial plants. A simple representation of the combustion phenomena based on energy transfers between particles and the action of specific molecules is presented. The pressure venting due to the vent breaking is calculated from thermodynamical characteristics given by the model anti taking into account the mass I ate of discharge of the different products deduced from the standard orifice equations. The application conditions determine the fuel ratio of the used mixtures, the nature of the chemical kinetics and the calculation of a universal set of parameters. The proposed development is compared to Bartknecht's experimental results and shows the model representativeness for varied dust suspensions (cornstarch, cellulose and aminophenazone) in very large use conditions such as the concentration in a rich or a lean mixture, the vessel volume or its geometry and the choice of the vent area or the venting pressure. The first results indicate correct tendencies in the predictions and it seems interesting to precise this evaluation in the future with vented gaseous mixtures.