Experimental and Theoretical Study of Flame Inhibition by Bromine-Containing Compounds

摘要

The present paper represents the first effort to date in which a combined experimental and theoretical approach has been used to study the effects of several inhibitors on hydrocarbon-air flames. This work is part of an attempt to build a consistent picture of chemical kinetic flame inhibition, beginning with a simple halogen molecule such as HBr and progressing sequentially towards more complex and more practical inhibitors such as CF sub 3 Br. Inhibition efficiency can be defined as the rate of flame speed reduction, the amount of flame speed change per unit inhibitor added. Both the numerical model and the flame tube measurements found that the inhibition efficiency gradually decreases as the amount of inhibitor is increased. The present experimental and modeling results are shown, together with earlier data for CF sub 3 Br-CH sub 4 -air and CF sub 3 Br-C sub 3 H sub 8 -air as well as HBr-CH sub 4 -air, CH sub 3 Br-CH sub 4 -air and CF sub 3 Br-CH sub 4 -air. In the numerical study it was found that a stoichiometric methane-air mixture with up to 8% methyl bromide could support a flame, propagating at a speed of about 5 cm/sec, even though the addition of the first 1% of CH sub 3 Br had reduced the flame speed from 38 cm/sec to about 26 cm/sec. Extensions of the model to include CF sub 3 Br are currently under development. The available experimental data suggest that CF sub 3 Br is somewhat more efficient as an inhibitor than HBr or CH sub 3 Br. (ERA citation 06:021731)