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>Would a crash be sufficient to cause a sudden aerosolization of the lng? Well yes, but actually no. You can't get a freight train up to the kind of speed you

>Would a crash be sufficient to cause a sudden aerosolization of the lng? Well yes, but actually no. You can't get a freight train up to the kind of speed you need to create an "instantly dump the contents of the pressure vessel" type crash without creating a "slowly vent the contents out" type crash first. You would need to use a bomb to rupture a pressure vessel to get the kind of fuel/air mix you need for an explosion or fireball. Fuel-air explosives operate in this manner. But they are devices with countless engineering man-hours spent making them actually work and fairly precise manufacturing. Parking ye ol' Winnebago (or Penske, if you're a history buff) beside the tracks and waiting for the train to go by is not going to be a very productive approach. Look at people blowing up propane tanks on YouTube. At best they get a fireball. I'd much rather have nat-gas wafting up and away rather than crude oil, propane, or some other volatile that sits at ground level.

Retric 6y ago
You get real differences of scale which makes smaller models inconsistent with what happens in a train derailment. Lac-Mégantic rail disaster for example had some serious explosions from oil.
- Arnt 6y ago
  According to the Wikipedia article there was much destruction, but... that happened when the oil flowed where it shouldn't and then burned in places where one really doesn't want it to burn. Lighter-than-air gas is crucially different. If you let that leak out it won't flow downhill through the city, it'll go straight up. Of course you can argue that gas is dangerous, but not by example of an accident where most of the flammable material flowed away (and caused harm elsewhere) instead of either burning or exploding at the site.
  - Retric 6y ago
    LNG isn’t a gas, it’s a cryogenic liquid like liquid nitrogen except flammable. If we are talking say 100+ DOT-111 tank car‘s that’s 3,450,000+ gallons which isn’t going to simply fly into the air instantly. The phase change from liquid to has takes significant energy at the scale which takes time. Again it’s a question of scale, you don’t think of say molasses as fast moving liquid but increase the scale to 2.3 million gallons and you can be talking about a 25 foot tall 35 mph wave. https://en.wikipedia.org/wiki/Great_Molasses_Flood https://en.wikipedia.org/wiki/Great_Molasses_Flood
    - Arnt 6y ago
      AIUI it's not flammable. It is flammable when mixed with air in the right proportion, but if it's mixed with air it is a gas and rises straight up, rather than flow as a wave across the landscape. You can't have your cake and eat it.
      - Retric 6y ago
        Again small scale vs large scale. If your talking a square foot of the stuff then it’s going to rise like your suggesting. Cover a few acres in LNG you get complex boundary layer interactions and giant swirls of natural gas mixed with air. Read up on how you can get temperature inversion layers in the atmosphere. In your model that kind of effect shouldn’t happen, but actual fluid dynamics gets complicated.
        Arnt 6y ago
        Explain how you get spontaneous combustion in the spots where the mixture is right. Or were you thinking about transporting LNG together with something that that would help start a fire?
        Retric 6y ago
        Train crashes have plentiful ignition sources as metal scrapes across metal. Oddly enough it’s surprisingly common for train crashes to result in fires ex: https://youtu.be/vww5V-xmtzs https://youtu.be/vww5V-xmtzs or https://baltimore.cbslocal.com/2016/07/06/recent-derailments-bring-to-light-risks-of-oil-trains-in-city/ https://baltimore.cbslocal.com/2016/07/06/recent-derailments... or the original disaster I mentioned. At which point those secondary fires can easily ignite the literal pools on LNG being described.
        Arnt 6y ago
        I've thought about this a few times now. Would you describe this as a noticeable risk compared to driving around in a car, in urban traffic, with gasoline? Or are you comparing it rather to an alternative that more or less avoids transport of LNG?

Retric 6y ago

You get real differences of scale which makes smaller models inconsistent with what happens in a train derailment. Lac-Mégantic rail disaster for example had some serious explosions from oil.

Arnt 6y ago
According to the Wikipedia article there was much destruction, but... that happened when the oil flowed where it shouldn't and then burned in places where one really doesn't want it to burn. Lighter-than-air gas is crucially different. If you let that leak out it won't flow downhill through the city, it'll go straight up. Of course you can argue that gas is dangerous, but not by example of an accident where most of the flammable material flowed away (and caused harm elsewhere) instead of either burning or exploding at the site.
- Retric 6y ago
  LNG isn’t a gas, it’s a cryogenic liquid like liquid nitrogen except flammable. If we are talking say 100+ DOT-111 tank car‘s that’s 3,450,000+ gallons which isn’t going to simply fly into the air instantly. The phase change from liquid to has takes significant energy at the scale which takes time. Again it’s a question of scale, you don’t think of say molasses as fast moving liquid but increase the scale to 2.3 million gallons and you can be talking about a 25 foot tall 35 mph wave. https://en.wikipedia.org/wiki/Great_Molasses_Flood https://en.wikipedia.org/wiki/Great_Molasses_Flood
  - Arnt 6y ago
    AIUI it's not flammable. It is flammable when mixed with air in the right proportion, but if it's mixed with air it is a gas and rises straight up, rather than flow as a wave across the landscape. You can't have your cake and eat it.
    - Retric 6y ago
      Again small scale vs large scale. If your talking a square foot of the stuff then it’s going to rise like your suggesting. Cover a few acres in LNG you get complex boundary layer interactions and giant swirls of natural gas mixed with air. Read up on how you can get temperature inversion layers in the atmosphere. In your model that kind of effect shouldn’t happen, but actual fluid dynamics gets complicated.
      - Arnt 6y ago
        Explain how you get spontaneous combustion in the spots where the mixture is right. Or were you thinking about transporting LNG together with something that that would help start a fire?
        Retric 6y ago
        Train crashes have plentiful ignition sources as metal scrapes across metal. Oddly enough it’s surprisingly common for train crashes to result in fires ex: https://youtu.be/vww5V-xmtzs https://youtu.be/vww5V-xmtzs or https://baltimore.cbslocal.com/2016/07/06/recent-derailments-bring-to-light-risks-of-oil-trains-in-city/ https://baltimore.cbslocal.com/2016/07/06/recent-derailments... or the original disaster I mentioned. At which point those secondary fires can easily ignite the literal pools on LNG being described.
        Arnt 6y ago
        I've thought about this a few times now. Would you describe this as a noticeable risk compared to driving around in a car, in urban traffic, with gasoline? Or are you comparing it rather to an alternative that more or less avoids transport of LNG?