Methane is usually the ‘source of ignition’ and the real deadly punch is provided by the coal dust. As the explosion proceeds it gains strength as it proceeds outside the mine. The coal dust gains power as picks up more dust on the way out.
Gotta make ya wonder why there wasn’t at least a catastrophe per week back when miners were using carbide headlamps . . .
This wasn’t a coal explosion, at least not likely. That would have blown out the back of the plant where the coal grinding equipment is. It is right below the boiler and the coal pipes go up outside of the part of the plant where all of the damage is.
The damage is in an area below the main turbine floor called the mezzanine. Lots of pipes and stuff there but not really much machinery. There are high pressure feedwater heaters in this zone but they run cooler than the main steam and reheat steam lines or the turbine.
But, lots of things could be the cause, just not coal.. this is the least likely.