The Problems of Porous Flame-Arresters

It is known that the porous flame-arresters are based on the concept of critical diameter. They are used in the pipe lines with combustible gases when it is necessary to prevent accidental propagation of deflagration or detonation. In spite of apparent simplicity of the devices there are sometimes failure in their function due to as a rule inadequacy of operating conditions to technical requirement of the design. It is the consequence of some simplification of real processes of flame propagation and quenching in narrow channels and porous media. As a rule when designing the flame-arresters there are not taken into account some complicated factors like mass force action, gas flow properties (velocity, turbulence, multiphase), force interaction of the flow with a porous medium, chemical properties of the porous medium surface, and etc. Laminar burning velocity is the only used characteristic of reactivity of combustible gas. But it does not always adequacy represent the behaviour of various types of flames, e.g., cool, chain and thermal. It is usually not taken into account the boundary conditions of entering of combustion wave into porous bed of the flame-arrester and arising in this case of non-stationary and steady-state combustion regimes. These factors may cause failure in operation of porous flame-arresters and may lead to disaster.