Inhibition of Premixed Methane Flames by Manganese and Tin Compounds.
Inhibition of Premixed Methane Flames by Manganese and
Linteris, G. T.; Knyazev, V. D.; Babushok, V. I.
Combustion and Flame, Vol. 129, No. 3, 221-238, May
premixed flames; manganese; tin; experiments; flame
extinguishment; fire suppression; halon alternatives;
kinetic mechanism; organometallics
The first experimental measurements of influence of
manganese- and tin-containing compounds (MMT, TMT) on
burning velocity of methane/air flames are presented.
Comparisons with Fe(CO)5 and CF3Br demonstrate that
manganese and tin-containing compounds are effective
inhibitors. The inhibition efficiency of MMT is about a
factor of two less than that of iron pentacarbonyl, and
that of TMT is about twenty-six times less effective,
although TMT is about twice as effective as CF3Br. There
exist conditions for which both MMT and TMT show a loss
of effectiveness beyond that expected due to radical
depletion, and the cause is believed to be particle
formation. Kinetic models describing the inhibition
mechanisms of manganese- and tin-containing compounds
are suggested. Simulations of MMT- and TMT-inhibited
flames show reasonable agreement with experimental data.
The decomposition of the parent molecule for the tin and
manganese species is found to have a small effect on the
inhibition properties for the concentrations in this
work. The inhibition effect of TMT is determined mostly
by the rate of the association reaction H+SnO+M <->
SnOH+M and the catalytic recombination cycle is
completed by the reactions SnOH+H<->SnO+H2 and
SnOH+OH<->SnO+H2O. The inhibition mechanism by
manganese-containing compounds includes the reactions:
MnO + H2O <-> Mn(OH)2; Mn(OH)2 + H = MnOH + H2O, and
MnOH(H2) and the burning velocity is most sensitive to
the rate of Mn(OH)2 + H <-> MnOH + H2O.