Lubrication drift from Tornado thread.

Agreed that getting yet more tubes into and out of the firebox would be another challenge, then passing those hot tubes back through the steam space(9?) is going to put most of what you have gained back in to the boiler, but the gimme is that you create extra heating surface without alteration to the desired hydraulic depth of the tube array. I would be very surprised if this hasn't been tried, probably earlier on in the development of superheating and found to be troublesome...

 

Does anyone know any more about the LSWR locomotive described below, which apparently had a hermetically sealed tube?
https://en.wikipedia.org/wiki/Jacob_Perkins#Steam_power

 

There is nothing in Bradley that would meet that description; he had access (amongst other things) to the LSWR Board and other minutes. Bear in mind as well that in 1836 the LSWR was still being built; it didn't open for traffic until 1838. The only locomotives apparently owned by the LSWR at that date were three (one each from Thomas Banks and Co; C. Tayleur and Co; Edward Bury) that were purchased in 1835 / 36 and used during construction. Details are unknown but presumably similar to other contemporary locomotives from those firms. The next locomotives purchased by the LSWR didn't arrive until 1838.

So my hunch is that the Wikipedia page probably has some crossed wires somewhere, especially as the statement is unreferenced.

Tom

 

Reference #8 in the Wikipedia page mentions Ahrons, so there may be something in there about it.

 

This discussion has gone a log way from Tornado so any chance the not Tornado bits can be hived off into a tread of their own?

 

It's done regularly in miniature, look up radiant superheaters. They're just regular superheaters extended into the firebox. Austenitic stainless steel is the usual material, they glow red hot in operation but done properly are generally perfectly reliable and IMO have a noticeable effect on coal and water consumption.

In full size you could do it with one of the Inconel alloys, but the superheat temperatures would probably be prohibitive for good lubrication even with the full Porta/Wardale treatment. In miniature the starting temperature of steam at say 80psi is much lower, and the thermal losses to the cylinder block proportionally greater, so radiant superheaters work perfectly OK with slide valves and hydrostatic lubricators in 5" gauge.

 

I suppose in dream engineering world with suitable use of unobtanium and other high performance materials the ideal superheater elements would exit the boiler in the firebox to feed cylinders at the rear of the locomotive.

 

That would work of course because you could use friction free unobtanium ceramic compounds on pistons and cylinder liners...

 

With a conventional superheater, the bends at the firebox end are in contact with gas almost as hot as in the firebox.

 

But in a flue tube the whole superheater element is exposed to said hot gas.
If you superheat in the firebox do you then
a) feed the potentially very very hot steam externally straight to the steamchest, perhaps via a feedwater heater ? or
b) pass it back through the steam space which would -cool the superheated steam / warm the pre superheated steam, somewhat but would expose the apparatus to quite an extreme temperature differential ( though as you point out - not that different to that which tubes at the firebox tubeplate are exposed to)

 

Its been fifty or more year since I filled a mechanical lubricator up .But do the y still have a fine gauze filter at the top to stop foreign bodies in the filling can going in to the lubricator.? It was a slow job in the winter with cylinder oil ,which was more like pouring thick treacle .My moneys on a blocked oil pipe with Tornado.

 

Yes they do - or at least should do. I wouldn't put money on anything at all - there's lots of things that could have gone wrong in a cylinder lube system.