Very explosive indeed. A well known hazard. But nowadays the risk appears to be from the considerable wind energy involved, especially with the comparatively high efficiency airfoils of modern wind turbines.
Seems a bit daft not to have an automagic mechanical method of turning the the thing to face the wind properly. Wind driven grain mills had that FFS! Maybe even a means of feathering the blades without needing electrical power as well. Piss poor cheapo design...
He he, though I do like the sublimininal link between this turbine fire and 70,000 scottish homes being without electricity...
Our power went off last night about 2130, the auto reclosure tried to put it back on but after it's three attempts, in very quick succession, locked out. Power came back at 0430. Batteries in UPS are shagged, it lasted all of 10 seconds before going critical. B-(
I was once involved in dust explosion issues. It isn't the initial dust explosion that gets you - it merely disturbs all of the accumulated dust in the rafters and building structure. If it occurs then the secondary dust explosion is devastating. Ironically the product being milled at the time was an anti-oxidant for vulcanised rubber. They had the building rebuilt with one very weak sacrificial lightweight wall and almost no horizontal surfaces for dust to collect on the inside.
There is a cute demo of dust explosions involving a balloon, rubber tube, some flour, a candle and a biscuit tin. Do not scale it up!
Regards, Martin Brown
This was a brake failure a few years back:
The tips of the blades are travelling >100 mph; diffiuclt to engineer a delicate failure mode in the circumstances. Still...
Gwynne
Mart> > >
It is believed that two famous ship sinkings, the USS Maine and the Lucitania, were both due to coal dust explosions.
Both events precipitated the US into war.
It may be believed by some. I'm really not sure what sunk the Lucitania, or even if the ship was ever constructed. However the Lusitania was sunk by a torpedo fired by the German U-boat U20 and Kapitänleutnant Walther Schwieger recorded that fact in his log. Schwieger postulated that a second coal dust explosion may have occured, but that was speculation and it is equally likely that it could have been one of the boilers rupturing.
We'll not know the exact sequence of events I suspect, but I think it's stretching it to claim that it was a coal dust explosion that sunk the ship. It was heading to the bottom after the torpedo hit it.
You have to remember that these things were designed to be used in a climate with not much wind. There is no need for all this protection in a climate where it is seldom windy enough to be a problem.
Wrong dennis.
That correct,, because you wouldn't put wind turbines there at all.
You mean there's a *right* dennis? Gosh.
He has said at least three things that are recognisable and reasonable descriptions of a real world known to most of us, this week.
Compred with drivel and harry, he is obviously taking the medication sporadically.
The risk of explosion in flour mills and big bread factories is still very real.
The basic problem is that fine flour finely dispersed in air is basically a fuel-air explosive.
Terry Pratchett doesn't make much stuff up - he used a flour explosion to great effect in his "Monstrous Regiment".
See what Martin Brown says elsewhere:
"There is a cute demo of dust explosions involving a balloon, rubber tube, some flour, a candle and a biscuit tin. Do not scale it up!"
Emphatically: DO NOT SCALE IT UP!
(My late father in law was a safety inspector at Allied Bakeries and the HSE at various times in his career. He dealt with fatal accidents pretty much all the time. I saw some of the photos...)
Rowland.
The fact that the RMS Lusitania was hit by a torpedo fired by the U-20 had more than a little to do with its sinking.
"Torpedo hits starboard side right behind the bridge. An unusually heavy detonation takes place with a very strong explosive cloud. The explosion of the torpedo must have been followed by a second one [boiler or coal or powder?]... The ship stops immediately and heels over to starboard very quickly, immersing simultaneously at the bow... the name Lusitania becomes visible in golden letters"
As for the USS Maine: the USA was looking for an excuse to have a war against the remains of the Spanish empire. Quite what set things off in that case is unknown: the two leading theories are a mine or spontaneous combustion of coal in the bunkers.
But it was sunk by the explosion of gun propellant:
"Later investigations revealed that more than 5 long tons (5.1 t) of powder charges for the vessel's six and ten-inch guns had detonated, obliterating the forward third of the ship"
1974 Rickover investigationAdmiral Hyman G. Rickover became intrigued with the disaster and began a private investigation in 1974. Using information from the two official inquiries, newspapers, personal papers and information on the construction and ammunition of Maine it was concluded that the explosion was not caused by a mine. Instead spontaneous combustion of coal in the bunker next to magazine was speculated to be the most likely cause. The Admiral published a book about this investigation, How the Battleship Maine Was Destroyed, in 1976.[3]
1998 National Geographic investigationIn 1998, National Geographic Magazine commissioned an analysis by Advanced Marine Enterprises. This investigation, done to commemorate the centennial of the sinking of Maine, was based on computer modeling, a technique unavailable for previous investigations. The conclusions reached were "while a spontaneous combustion in a coal bunker can create ignition-level temperatures in adjacent magazines, this is not likely to have occurred on the Maine, because the bottom plating identified as Section 1 would have blown outward, not inward," and "The sum of these findings is not definitive in proving that a mine was the cause of sinking of the Maine, but it does strengthen the case in favor of a mine as the cause."[31] Some experts, including Admiral Rickover's team and several analysts at AME, do not agree with the conclusion."
Rowland.
They do - if you look at the photo of the burning turbine on the BBC, you can see that the failed turbine was `round the other way' to the two other (suriviving) turbines in shot.
Clearly, some sort of fault in the high wind survival mechanism occurred.
That's what megawatts do for you.
Rowland.
It's not so much the efficiency of the aerofoils as the simply huge quantities of energy involved.
There was simply too much power being dumped into the gearbox/generator arrangement at the top of the tower - in winds like that, who needs particularly high efficiency to convert vast power?
I'd love to know what the failure mode was, though.
Rowland.
alegedly it was not switched on, so it had no power - even grid power to turn or feather.
Like Gen I and II nukes, the safety measures are not passive.
Ah. Oops. Now that's a c*ck-up.
(the thing did have access to power - else it couldn't have caught fire, yeah? Great big oodles and gobbets of kinetic energy were being dumped into it from the wind and converted into mechanical rotational energy via its blades, and it's not beyond the wit of engineers to come up with a design that can use that mechanical rotational energy to turn the energy conversion assembly into the wind, feather the blades, and apply a brake rather than just let the thing turn all the energy into heat with the (to me) entertainly firey consequences we saw. I'll tell you what, if anyone wants a reason to object to wind turbines near there home, that turbine failure's a pretty good one. Imagine if the debris had been due to land in a people-occupied area... That wouldn't be at all funny.)
Not many people have much information about those designs, you know.
But about the wind generators: beats me how they would or could design something that expensive without ensuring that it would protect itself in high winds without external inputs being required. But then again, you do want to be able to turn it fully *OFF* so that human beings can do maintenance on it without being at risk of the thing moving around of its own accord.
So I suppose this one's down to `operator error' regardless of the design details.
As for nukes...
Not many of the early nukes could produce a big nuclear bang accidentally - one notable exception was Violet Club ('cos Britain felt it needed a big bang bomb and hadn't got thermonuclear bangs sorted out at the time):
Plutonium bombs need a synchronized squeeze - none of them will deliver a high yield nuclear detonation unless they get that, which takes triggering of the explosive lens by the very carefully designed trigger circuit.
So in the case of *those* nukes, they're sort-of inherently safe(ish). An accidental detonation of the explosive lens can't be adequately synchronized for a full yield explosion.
Moreover, you need a source of neutrons-with-a-suitable-energy. I don't know many of the details - but unless that's fitted and does its thing, the bomb can't produce a full yield explosion (although some designs like Violet Club could give a seriously bothersome nuclear bang without).
Here's a thing:
"Green Grass/Violet Club was the first UK-deployed weapon to dispense with the crude polonium and beryllium impact or crush type initiators used in Fat Man and other early US weapons together with the British Blue Danube and Red Beard. Instead it used an Electronic Neutron Initiator or ENI, known as Blue Stone which had the great advantage of being adjustable, allowing the neutron burst to be triggered at precisely the right moment. The burst heights of Green Grass were optimized for either maximum overpressure without allowing fireball contact with the ground, or to maximise the ground area subjected to a 6 psi overpressure; respectively 3,500 ft and 6,200 ft above ground level,[23] using a barometric fuze backed-up with an adjustable clockwork timer fuze[24] and fail-safe impact fuzes. Most of these mechanisms originated from Blue Danube although the radar altimeter fuze was omitted.[25] The electrical power for these fuzing mechanisms and the firing mechanisms of the 72-lens 45 inch diameter implosion device came from lead-acid accumulators located in the tail of the Blue Danube casing. These were commercially-sourced six volt motorcycle batteries."
I've heard that tritium is used in some designs - supplied in what has been hinted to me is effectively a detachable bottle. I'd be unsuprised if that arrangement weren't widely used.
(I used to know this chap who didn't actually tell me anything at all about the design of nukes, but did say `no' to some of my guesses and also asked me some leading questions.)
Thats how they 'come' several accidents have happened erecting them and not having them braked when they are assembled.
Its a problem, You have rigged the ship but have no power for the capstans - if the sails aren't reefed over she goes..
Bit of both.
Should have braced the mainstay and battened down the hatches..
None of themm could produce a big bang - even the plutonium breeders.
Its takes precision to engineer an atomic explosion. and 95% or better pure material. You wont get than in a slag heap of molten fuel rods..
I think its fair to say that Chernobyl is the worst accident a nuclear power station COULD generate. Out of control pile with no shielding and on fire.
:-)
There's a little bit of a debate about at the moment on wing rigs for sailing vessels. They're far more efficient than a bit of canvas stuck up an old tree - or even a bit of mylar with carbon-kevlar reinforcements on an epoxy-carbon section - but they're B***rs to reef or furl.
I don't think so. If one of the Japanese ones had done a Chernobyl type accident when the earthquake struck the tsunami would have made it far worse than Chernobyl was.
Just as well they were well enough (just) designed not to fail on just an earthquake.
I thought about trying to build an inflatable sail. One that would inflate itself into a wing shape but I never got around to more than thinking about it in the pub about 30 years ago.
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