Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
Jerome has a valid point...

Have you ever filled a propane tank? Or refilled a smaller portable tank from a propane tank? You get frost & ice all over everything. That is similar to what would happen with an LNG leak.

That is because when you transfer propane you are in effect 'boiling' the liquid in the larger tank to generate the gas pressure to fill smaller tank.  Same thing happens if you use those backpack camp stoves (not the liquid fuel but canned gas)... you get frost all over... especially as it funs out.

That frost is the result of moisture in the air condensing & freezing on the outside of the tank to provide the 'heat' to boil the propane, butane, whatever inside the tank. The 'latent heat' of the water vapor condensing & then freezing plus the temperature drop is transfered to the propane/butane/whatever to 'boil it'... overcoming the latent heat of the hydrocarbon so it turns from a liquid into a gas... basic heat transfer & thermodynamics problem.

The same thing would happen with LNG... to get a whole tanker to vaporize to explode would not only take a leak but also a whole lot of heat (equivalent to the latent heat of natural gas times the mass of the LNG)... A LOT. You spring a big leak in one of those tanks... and some LNG will vaporize immediately and will escape but as it does the temperature of the LNG remaining liquid will plunge... you will turn that tank into an iceberg pretty fast... and the resistance to heat transfer through the ice will dramticly slow the future release. It could still be a huge problem but it would not make a very good bomb.

Another reason for this is that for gases to be 'explosive' requires that the mixture be right... not too much gas in the mixture and not too little... but just right within some error bars which depends on the specific gases and pressures and such.

This is why those fuel air bombs are so tricky... they have to first disperse the combustibles out a long way over the target... mix them evenly and in the right concentrations... then ignite. Not easy to do even when the things are designed to do it... very difficult to do 'by accident'.

I'm not saying LNG is 100% safe or that something awful could never happen... just that it isn't more dangerous than other fuels and in some respects less so.

Hope this helps.

"On the Internet, nobody knows you're a dog." - Peter Steiner

by dryfly (jjwhodat at hotmail dot com) on Fri Jun 24th, 2005 at 03:12:08 PM EST
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