7 cars of a 98 car ethanol train derailed, with at least one catching fire. Bridge collapse?
http://ktar.com/story/644341/10-ethanol-tanker-cars-derail-2-catch-fire-in-south-dakota/
Could wish that someone had included a ‘before’ picture of the bridge. One photo, on Microsoft Edge, showed that the locos and a covered hopper (buffer car) ran a few hundred feet and then were parked clear of the little rural road crossing that the local fire responders used to access the fire. The first tank car is at the bottom of the fill, the second is on the fill and the third is the lighter-appearing one balanced over the bridge abutment.
So an ethanol train derailed, there was a clear-flame fire (NASTY!!) but the local fire companies dealt with it. Then it was put on Microsoft Edge - and every technologically unqualified ignoramus immediately piled on. The first poster wanted to know why there wasn’t a pipeline to handle the ethanol. (If he knew anything about ethanol he could have answered his own question.) Another thought that the county/state/Federal government might have owned the bridge. (??) Then the usual political rat-fight started, and I came here to read some saner comments.
I’ll be back later. Hopefully, there will be more hard information.
Chuck
Three GOOD things about this derailment.
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There were no injuries ofr fatalities.
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It occurred in the middle of no where, so no civilians or structures were in danger.
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It was ethanol which will burn but NOT explode like crude oil.
I live about an hour away from this derailment. In fact, if the train hadn’t derailed, it would have passed by on the tracks 6 blocks from my house. Our local paper, the Sioux Falls, SD Argus Leader-the state’s biggest newspaper put an article about the derailment on page 7 of section C.
I can understand the confusion about who owns the tracks. It was a Milwaukee Road line that had been taken over by the state of SD and had money pumped into it. A few years back, the line was sold to BNSF.
Crude oil does not explode. It burns. When contained It can result in a Boiling Liquid Expanding Vapor Explosion. That has nothing to do with flamability. Water can produce a BLEVE.
crude oil explodes
Isn’t it the vapors that explode?
This seems to be the spot. It looked like quite a bridge for what looks like a babbling brook in 2-D.
Simple. Crude oil consists of many components of oil. Some crude contains propane (camping fuel), butane (cigarette lighters), ketane (gasoline) and many other components. Heavy crude contains more of the bunker b and c oils and tar components but the light Baken Crude contains much more of the volatile gasses that will explode. I thought you should have learned this by now if you have been following these stories for the last year. The Baken needs to be degassed to reduce its volatility. So after being shaken and bounced by the train, mixed with the air in the car and then exposed to a spark or flame, the gasses can and too often do explode. Just like they do in your automobiles cylinders.
I’ve always been intrigued by the use of the terms "flamable and “inflamable.”
More BS. No such thing as “ketane”. Like all petroleum products, gasoline is a mixture. Chevron SDS shows 12 ingredients. It does not explode in an engine. It burns at a controlled rate. Obviously when vaporized and mixed with air it burns faster. Any liquid in an enclosed vessel can produce a “bleve” when the pressure is enough to burst the vessel. This is commonly complicated by heat weakening the vessel.
The difference, in this case might be that there is a substantial difference in the flash points of gasoline, many of it’s ingredeients are present in a light crude oil, and ethyl alcohol. The difference is about 100 degrees F. which makes ignition much more likely.
A bit more complicated. The basis of crude oil is hydrocarbons - chemicals made up only of carbon backbones with attached hydrogens. The ‘simpler’ ones have only a single chain, the shorter of which are gases (methane, for example, a major constituent in natural gas, CH4, or propane, C3H8). Your ‘cetane’ (properly spelled) is a C20 chain (named after whale oil) and is the ‘reference’ for diesel fuel as octane (C8, but not necessarily straight-chain) is the reference for gasoline.
As an aside, substituting a hydroxyl radical (-OH) for one of the hydrogens can convert a hydrocarbon to an alcohol. Methane becomes methanol, or wood alcohol, and ethane (C2H6) becomes ethanol, C2H5OH, the ethyl alcohol that’s in alcoholic drinks. Note that substituting the hydroxyl makes the gases into liquids, but even so, you can’t shove them into pipelines until you reach butanol … which isn’t cheaply made by fermentation as ethanol is.
Here is the situation with BLEVE as it applies to Bakken ‘explosions’ – and with analogy as midget noted to steam boiler explosions. The problem is not that the gases segregate inside the car; it is that they remain dissolved in the liquid crude under pressure as it becomes heated. When pressure is relieved, the gas components expand dramatically as small bubbles within the liquid, as when a soda bottle is dropped and then opened. Note that the ‘shove’ from these bubbles is cumulative outward from the center,and the periphery of the liquid hence experiences high acceleration; if there is space between the liquid surface and the wall of the tank or vessel that encloses it, this acceleration can build up very high momentum that then produces hydraulic shock when it hits the tank wall. This is a force much higher than what would be produced by equilibrium pressure, and it also produces very fast expansion and evolution of much of the liquid oil carried along entrained with the
Excellent! Couldn’t have said it better.
As Wizlish says, octane is not necessarily a straight chain hydrocarbon–indeed, iso octane (or, isooctane) is highly branched–two methyl (CH3) groups on the second carbon in the chain and one methyl group on the fourth carbon. And, iso octane has an octane rating of 100; n-heptane (seven carbon atoms in a straight chain) has an octane rating of zero.
It looks like the train only traveled 7-8 car lengths after derailing. How fast do trains travel here normally?
Less than 25MPH, you are in the bottom of a sag for Prairie Creek (Br 596.7) and running on tired 90# jointed rail unless something changed in recent history.
(you can do all you want to with surfacing and ties, but rail joint memory from years of minimal or no maintenance in the past won’t go away easilly. Add in open deck timber pile spans and poor soils and the result is [+o(]. That roadmaster is a busy fella even without the mechanical and operating wildcards added. )
Currently known in IUPAC as the dreaded 2.2.4-trimethylpentane. A picture worth a thousand words:
How did you get that snazzy subscript to work in our BBcode?
BTW, as an aside neither end of the ‘octane’ scale is fixed – ethanol and LPG both have research octane numbers higher than 100, and aviation gasoline used to go as high as “140LL” through the use of tetraethyl lead. There is now a no-lead “100 octane” with the proper low vapor pressure for aircraft use – I believe it is blended with 1,3,5-trimethylbenzene (anyone know how resonant this is?).
At the other end, plain straight-chain octane has a RON of NEGATIVE 19 according to an orgo text I have seen.
You need to read this. https://en.wikipedia.org/wiki/Avgas.
The ONLY avgas you’re likely to find these days is 100LL. The unleadeds are still in the development and testing stage and the heavily leaded ones are no longer available.
How did I get the subscript?[:D] I used the smallest font available (8 point), and it came out almost like subscript with the 14 point that I prefer–of course, it did not drop below the level of the 14 point as a proper subscript