Skip to main content

View Diary: Facts about the Texas Explosion (57 comments)

Comment Preferences

  •  Not a BLEVE... (0+ / 0-)

    Or at least, I don't believe it. BLEVEs usually require damage to a tank (usually an overturned railcar or similar) specifically with damage to a pressure relief valve, plus a fire under the car or tank. That seems unlikely here.

    Ammonium nitrate is written all over this. Look at the Texas City disaster, the Oppau disaster (and a smaller predecessor), or the Ryongchon disaster. Large quantities of burning AN going from deflagration to detonation, often with water or steam being used, in a confined area.

    Ammonium nitrate is not especially dangerous in small amounts, but has a number of odd properties that make it very dangerous in large amounts.

    E.g., prior to the Oppau disaster, it was not unusual to use dynamite (!) to break up big chunks of it at the plant after they had congealed. This had reportedly been done thousands of times prior to the disaster. As the major component of ANFO (the Oklahoma bombers used this - 96% AN, 4% Fuel Oil), it is a powerful explosive, but requires a powerful primary for reliable detonation.

    It will burn, and in large (multi-ton) amounts will undergo deflagration-to-detonation transitions. Adding water to burning AN makes this more likely, and was likely a factor in two of the explosions in Texas City, Ryongchon, and elsewhere.

    In the presence of modest amounts of contaminants, it can undergo autocatalytic decomposition, becoming quite warm and in large amounts, spontaneously igniting.

    Oppau explosion

    Texas City Disaster

    Ryongchon Disaster

    •  My reasoning (0+ / 0-)

      Looking at Google Earth, the anhydrous tanks appear to be located south of the building where the fire was. The fire was fairly large and if at that end of the building would have pretty much engulfed the tank. Now if that building is also where the ammonium nitrate was stored then all bets are off, and I lean to your side. But BLEVEs don't require a prior weakening of the tank skin. A fire is all that is needed, and the relief valve can be in perfect working order. I don't know the exact cause, but either could be this destructive.

      •  ... (0+ / 0-)

        BLEVEs don't require a weakening of the skin, but they do usually require a failing relief valve (or a very undersized one).

        To get a BLEVE, the burning needs to be under the tank -- fire heating the top of the tank will not be cooled well, and the tank will fail much sooner at the hottest/most-stressed point. (Thermal stratification will set in, allowing the top to heat much more quickly than the bottom.)

        Ammonia is also not a very good candidate for a BLEVE -- the flammability/explosion limits for ammonia are relatively picky -- 15% - 28%.

        Finally, it is know that there were large amounts of AN present. AN is well known to spontaneously decompose, particularly in the presence of water, heat, or contaminants, and large quantities are known to auto-ignite. Further, it is also known to transition from deflagration to detonation, especially in confined areas or when treated with water or steam.

        It's certainly possible that this was caused by cook-off of the anhydrous ammonia. But that's definitely not the way to bet.

Subscribe or Donate to support Daily Kos.

  • Recommended (145)
  • Community (68)
  • Elections (34)
  • Media (33)
  • Trans-Pacific Partnership (31)
  • Environment (30)
  • 2016 (29)
  • Law (28)
  • Culture (27)
  • Civil Rights (26)
  • Barack Obama (24)
  • Hillary Clinton (24)
  • Science (23)
  • Climate Change (23)
  • Republicans (23)
  • Labor (21)
  • Economy (19)
  • Marriage Equality (19)
  • Jeb Bush (18)
  • Josh Duggar (18)
  • Click here for the mobile view of the site