Explosion Venting Data and Modeling Literature Review
Taken from the documents summary:
This report provides a literature review and an analysis of key aspects of dust explosion and gas explosion venting. The review includes test data, theoretical models, and vent area equations in the NFPA 68 and EN14491 explosion vent standards.
Comparisons are made between the vent areas used in large-scale experiments and the vent areas calculated by the NFPA 68 and EN14491 equations for the reduced pressures measured in the experiments. The average values of the ratios of tested-to-calculated vent areas for dust explosions are 1.19 and 1.28 for the NFPA 68 and EN14491 equations, respectively. NFPA 68 and EN14491 calculated vent areas smaller than used in the tests occurred more often at low enclosure strengths and with low KST combustible dusts.
Phenomenological models and Computational Fluid Dynamics (CFD) models are being developed to simulate vented dust explosions, and these models should facilitate better understanding of how the test data can be extrapolated to account for the influence of varying dust cloud dispersion and ignition scenarios, and process equipment operating conditions.
The review of gas explosion venting data and modeling focuses on the effect of equipment and structural obstacles in the vented enclosure. These obstacles can cause the vented explosion pressures to be many times as large as the pressure developed without obstacles for the same gas mixture, vent area, and ignition conditions. The presence of obstacles is not explicitly accounted for in the NFPA 68 and EN14491 vent area equations.
Graphs and correlations are presented showing how the measured/calculated vent area ratios vary with the obstacle/enclosure area and volume ratios for both small and large obstacles. These correlations could potentially be further developed to facilitate inclusion of obstacle parameters in the deflagration vent guidelines. Several CFD models and phenomenological models have been able to reproduce the effect of obstacles on measured pressures in many experiments, and some of these models are being used to analyze hypothetical gas explosion scenarios in large obstructed industrial process facilities.