Comparison of explosion parameters for Methane-Air mixture in different cylindrical flameproof enclosures

摘要

Flameproof enclosures having internal electrical components are generally used in classified hazardous areas such as underground coalmines, refineries and places where explosive gas atmosphere may be formed. Flameproof enclosure can withstand the pressure developed during an internal explosion of an explosive mixture due to electrical arc, spark or hot surface of internal electrical components. The internal electrical component of a flameproof enclosure can form ignition source and also work as an obstacle in the explosion wave propagation. The ignition source position and obstacle in a flameproof enclosure have significant effect on explosion pressure development and rate of explosion pressure rise. To study this effect three cylindrical flameproof enclosures with different diameters and heights are chosen to perform the experiment. The explosive mixture used for the experiment is stoichiometric composition of methane in air at normal atmospheric pressure and temperature. It is observed that the development of maximum explosion pressure (P_(max)) and maximum rate of explosion pressure rise (dp/dt)_(ex) in a cylindrical flameproof enclosure are influenced by the position of ignition source, presence of internal metal or non-metal obstacles (component). The severity index, K_G is also calculated for the cylindrical enclosures and found that it is influenced by position of ignition source as well as blockage ratios (BR) of the obstacles in the enclosures.