[deangshaw]

Hi. I am working on a final year project in which a exhaust ducting is attached to a coal mine. I need to design some explosion protection for the unit, but I want to know how I can calculate the peak pressure of a methane explosion in a contained 110m^3 unit at the LEL of Methane/Air. Any help would be greatly appreciated.

Thanks

[curiouscat]

Hi. I am working on a final year project in which a exhaust ducting is attached to a coal mine. I need to design some explosion protection for the unit, but I want to know how I can calculate the peak pressure of a methane explosion in a contained 110m^3 unit at the LEL of Methane/Air. Any help would be greatly appreciated.

Thanks

Your post reminded me of a thumb rule I'd read a long time ago: Any contained hydrocarbon mixture can only generate a maximum pressure of 7 times the original gas pressure in an explosion.

The context was that for some small pressure vessels it is cheaper to just over-design them to contain the overpressure than to invest in complicated venting / flaring systems, especially if toxicity / flammability is a concern.

I never tried to reason out the 7-times thumb rule though. So be warned. It might be wrong.

[Enthalpy]

There is no simple computation possible, because an explosion is not a uniform process but a wave instead. Attempts with reaction heat, temperature ratio, and pressure ratio fail consistently. A flat propagation front can be evaluated approximately with great effort (and already uncertainties), but then you have all reflections, sections changes and more.

So: experimental data.