Experimental and theoretical investigations on passive flame arrestors: Fid-Bau Portal

Experimental and theoretical investigations on passive flame arrestors

Schwöppe, Patrick

Flame arrestors have a wide field of application in industrial processes. Wherever flammable materials are handled on an industrial scale (chemical industry, oil supply vessels, coal mines etc.) safety measures have to be taken in order to prevent harm from human life and damage from the plant even in case of operating errors or equipment failure. Usually the requirements on flame arrestors are high. For example, on a tanker ship the demand on the flame arrestor is not only to prevent a single deflagration wave from propagating to the protected side, but also to guarantee safety when a permanent flame is present ('endurance burning'). In passive flame arrestors flame propagation to the protected side is prevented by means of a porous structure the burnable mixture is flowing through. At present, no comprehensive theory that is capable of predicting the performance of such flame arrestors is available. Necessarily, in the absent of such a theory flame arrestors are developed mainly by experimental methods. In the past reliable flame arrestors that satisfy the criteria of international standards have been experimentally designed for a wide scale of standard fuels (methane, natural gas etc.). Differently to that there are other fuels (for example H2) where no solution could be found up to now. The motivation for this work is to develop a reliable theoretical basis for flame arrestors. A solid theoretical understanding serves as the starting point for a systematic and well-directed selection of the flame arrestor design. In this paper a mathematical modelling approach for the prediction of flame arrestor performance including failure is presented. The model accounts for heat transfer and combustion in a porous medium. Experimental results also are presented in order to verify the model. Stable operation of the flame arrestor was possible with a methane flame whereas flame penetration into the arrestor with subsequent failure within 10 minutes of operation was observed using hydrogen.