Welding cast iron

Cox tells of a post-war project, never implemented, to provide extra superheating in stop-start working by winding electric coils around the superheater elements and powering them from an adjacent diesel- electric shunter. It was abandoned before it was actually built because, whatever its thermal advantages, it was hard to see how you would practically use that efficiency.

Reply to
ian batten
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On the other hand you have to pump water into the boiler anyway, and pumping it from below atmospheric pressure doesn't take much more power than pumping it from atmospheric pressure, since the bulk of the work is getting from 1 bar to boiler pressure.

The pressure in the condenser is set by the temperature at which you can keep it. If you have a large sink at 10C available, the pressure will be 0.015 bar or so. That's pretty low.

Ian

Reply to
The Real Doctor

Thanks Andy.

Reply to
Roger Traviss

Sure - it can be done (Gurney, to add, did it with a jet of live steam). It does, however, add complexity, and make more onerous requirements of footplate crew and maintainance staff training. As railways in Britain were notoriously bad at both of those, it's hardly a surprise that condensers never found favour in this country...

Reply to
Andy Breen

Third fiddle to cheap maintainance (by poorly trained staff in ill-equipped sheds and workshops) and robust operation by inadequately trained footplate crews - at least in the UK (US: robustness, reliability and ease of maintainance; Germany: robust reliable operation, cheap maintainance costs...)

Reply to
Andy Breen

The early wrought-iron locomotive boilers were built up from many small plates (see: Puffing Billy in South Kensington for an - almost certainly

- 1814-15 boiler). These would be easier to bend to "near enough round" than the large "belt" plates used at a later date, and presumably the consequences of getting it not-quite-right would be less severe. Even after large plates became available, the smaller builders in the North-East preferred to use "long plate" construction for boilers, with long narrow plates running the full length of the boiler and rivetted up longitudinally. Again, forming these to "good enough" would probably easier (and required less specialised tools) than building up boiler in rings. Not saying it'd be easy to do in a colliery blacksmith's shop, but with skill and patience probably manageable (I suspect a fair amount of re-working of mis-bent plates would occur..). Certainly the specialised and expensive equipment needed to produce such a large casting as a locomotive boiler would not be needed. As to sealing - I gather from reading contemporary accounts from the early period that resource was often made to putting oatmeal (or similar) in boiler feed to seal small leaks. Not an approved additive for modern boilers, but it must have helped a bit..

Reply to
Andy Breen

Had rolls not been invented by then? No need for "near enough" if they had.

Reply to
Alex Potter

Originally introduced in warships as a source of short-term "sprint" power, IIRC (late 1870s, I think. Iris-class rings a bell here but I'm not going to go and pull Brown off the shelf to check..). Had the added advantage of allowing fuel saving the rest of the time by reducing the weight of machinery needed for sprint power. Got adopted widely (over-widely, and over-ambitiously) in warships after CALLIOPE sustained 110% of 1-hour power for 23 hours while escaping the typhoon at Apia in 1889 - she had a very good set of boilers and engines by Maudsley (and a very good chief engineer). As you say, the advantages were restricted to boilers with a more restricted draught path than the old large flues (where forced draught would simply have sucked the fire straight through [1]) - warship use of forced draught, and subsequent civil maritime use - followed the introduction of multitubular fire-tube boilers in place of the old flue type, and snowballed with the appearance of water-tube boilers (Bellevilles, and such..). For a bit of uk.r topicality, the multitubular fire-tube boilers were referred to at the time as "locomotive" boilers, even though - with the grate in a large flue - they were unlike anything used in main-line locomotives after the 1850s (apart from some L&Y 0-8-0s in the 1900s, I think...).

[1] which happened later, where boilers were over-forced. To a spectacular degree at times, such as in WW1 battlecruisers.
Reply to
Andy Breen

1814-15. Not sure. Pretty sure a colliery workshop wouldn't have been among the first to have them, though. And a good subset of early locomotives (and later ones, certainly through to the 1860s..) in colliery use were built by the colliery shops, in many cases without ordering in the boiler from outside.
Reply to
Andy Breen

South African Railways had a large and successful class of air-cooled condensing steam locomotives, and they worked in the desert not Siberia.

Nick

Reply to
Nick Leverton

harry wrote: [snip]

I can find a list of Seven classes of air cooled condensing locomotives. Five from the UK, two from South Africa, none from Siberia.

Heck, Harry caught talking shit, again.

Reply to
Steve Firth

Yes, but the aim there was to conserve water supplies, not improve efficiency. So long as the the steam could be condensed, it was enough in that application. IIRC the Siberian experiment was to try and reduce coal(?) consumption by improving efficiency, and it was found they only got a measureable improvement in winter.

Reply to
Andy Breen

In message , Andy Dingley writes

Priming is normal for any engine with an over full boiler, indeed before a steep bank that the fireman would have to watch the water very carefully, it wasn't unusual for the injectors to be kept going long after the water disappeared out of the top of the glass until priming started, then you knew you had a full boiler.

Reply to
Clive

In message , harry writes

Yes. Whilst a lead plug looks to be entirely of lead, it is in fact mainly steel with a bored core and this restricts the amount of steam and water needed to put out the fire.

Reply to
Clive

let a whole lot more steam

Why is there such a steep taper on the thread on the plugs? Wouldn't that make the whole plug fall out more easily?

Reply to
Matty F

"Lead plug" isn't the most helpful term anyway.

They're not lead, they're tin (with obsessive purity standards, depending on your regulatory body)

They're not steel bodies, they're a cuprous alloy so that they don't rust in - they are removed and replaced fairly frequently.

The "plug" isn't solid either. It's (an improved design, although not universal) a brass plug thickly soldered in by the tin plug around it. The idea is that once the plug softens, this core is blown out and then the whole plug is open. If it's a literal "lead plug", as for the older ones, then a small pinhole melts first and (if not too overheated) then jet of escaping steam can be enough to chill this and re-freeze it, so the plug never opens fully.

Reply to
Andy Dingley

Priming might be "inevitable" if you over-fill the boiler, but it's never "normal".

Look at the sad tale of 532 Blue Peter, if you want to see how bad priming can get.

Reply to
Andy Dingley

In message , harry writes

You keep an eye on the chimney, at the first sight of priming you turn off the injectors and the priming stops almost immediately, no damage and security in not letting the boiler get to low, allowing concentration on proper firing and fire management with just the occasional look at the sight glasses.

Reply to
Clive

In message , Matty F writes

The lead plugs I remember had a very large pitch but weren't tapered, though the ones around the boiler to assist in washout were.

Reply to
Clive

To carry this off topic digression on a little further, an interesting development of the '20s and '30s was what Brown Boveri & Cie marketed as the Velox boiler. The idea was to make a more compact boiler where the airflow could be managed to match the combustion conditions. The concept added a blower to the fresh-air side of the boiler (nothing too special there), but then had the clever idea of powering the blower by means of a turbine in the exhaust stream, rather like a turbocharger. These were large machines, so the turbomachinery in each case was multi-stage axial equipment. BBC then made the (for the time) radical step of taking such a device, increasing the pressure ratio by adding a few stages to the turbomachinery and getting rid of the boiler itself, just leaving the fire on its own. The resulting machine was installed in Neuchatel in 1939 and became the world's first gas turbine (the Neuchatel machine itself remaining in service as a back-up generator until about 10 years ago).

Robin

Reply to
bob

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