The gas explosion induced by the high-temperature surface
of coal
spontaneous combustion in goaf will cause a devastating blow to personnel
and equipment in the process of coal mining. Secondary explosion may
be induced by the high-temperature surface of coal spontaneous combustion
after primary explosion with the continuous emission of gas and the
ventilation of goaf. This will lead to new disasters for the ongoingrescue
operation. A high-temperature source explosion experimental system
consistent with the similarity and unity of goaf was designed and
developed based on the similarity criterion in this study. A CH4/air explosion experiment was carried out with the high-temperature
surface as an ignition source. The characteristics of secondary explosion
were studied, and chemical kinetics was analyzed. It is of great significance
to the safety of the process of mining production. The results show
that the secondary explosion limit (6.5–14%) is less than the
primary explosion (5.5–14.5%). Its explosion risk (F) is reduced by 15.6%. The key parameters P
max, T
max, and (dP
/dt)max of secondary explosion
at each concentration are lower than those of primary explosion. The t
e of secondary explosion is higher than primary
explosion. The most dangerous concentration of primary and secondary
explosions induced by the high-temperature surface is 11.5%. Carbon
oxides (CO2 and CO) and C2 hydrocarbon gases
(C2H2, C2H4, and C2H6) are generated after primary explosion. The
chemical kinetics of secondary explosion was analyzed with CHEMKIN Pro 2021. When the CH4 concentration
is <11.5%, the formation of the key free radicals ·H, ·O,
·OH, and CH2O is inhibited due to the formation of
CO2. When the CH4 concentration is ≥11.5%,
the formation of the key free radicals ·H, ·O, ·OH,
and CH2O is inhibited due to the generation of combustible
gases (C2H2, C2H4, C2H6, and CO) and inert gas (CO2). As
a result, the limit range of secondary explosion and the explosion
hazard characteristics are reduced. R156 and R158 played major roles
in the process of secondary explosion with the analysis of reaction
sensitivity.