Experimental study on suppression of methane explosion by porous media and ultra-fine water mist

An experiment of inhibition effects by porous media and ultra-fine water mist on stoichiometric methane/air (9.5% methane) explosion was investigated in a semi-confined transparent explosion vessel, which measures 80 x 80 x 1000 mm(3). The ultra-fine water mist concentration, porous media porosity factor and pore density were taken into account, and the explosion characteristics such as flame propagation and overpressure were compared and discussed collectively. The results indicated that the tendency of maximum flame propagation speed and maximum explosion overpressure in the upstream of porous media were significantly varied by changing the concentration of ultra-fine water mist, the porosity factor of porous media and the pore size. The porous media placed in the pipeline produced a quenching flame effect, and the addition of ultra-fine water mist reduced the pressure upstream of the porous media significantly. The combination of porous media and ultra-fine water mist existed a coupling inhibitory effect on methane explosion. Compared with pure methane, the time required for tulip flame production was increased. Furthermore, under 87% porosity factor, 20 PPI pore density and 1453.1 g/m(3) ultra-fine water mist concentration, the inhibition effect is the most obvious, in which the flame propagation speed was 12.8 m/s, the descending proportion reached 44.23% and the maximum explosion overpressure in the upstream of the porous media was reduced by 40.62%.