I've always had an interest in live steam but now I need it
duncan webster | 26/05/2022 12:36:44 |
5307 forum posts 83 photos | Posted by Christopher Jones 9 on 25/05/2022 20:42:34:
Back to the drawing board... Coal in my current design is a no go... Whats everyone's smallest coal fire box? Tich firebox is 2.125"*2.375" (I think) |
norm norton | 26/05/2022 16:59:41 |
202 forum posts 10 photos | I think you would have success with a 2.5" or 3" diameter fire tube inside a 5" Cornish style boiler tube. The grate could then support a 2" x 4" firebed which would produce more than a couple of kilowatts if 1" deep AND supported by an adequate draught. That should generate enough steam for a 2" stroke mill engine, perhaps bigger? Just my 'guesstimates' from running small steam locomotives. I would use a compressed air blower jet, up the chimney, to start and stabilise the fire until there was enough steam to take over. The problem will be getting a new design of boiler approved for use in public, but there is little doubt you could make a massively strong boiler from two tubes and two end plates. |
Nigel Graham 2 | 26/05/2022 17:18:22 |
3293 forum posts 112 photos | Norm - Christopher doesn't say where he is or if he's in a model-engineering society affiliated to one of the MELG Federations, but if he is, the boiler-testing problem should not too difficult. Depending on its boiler examiner... who can decline to test a boiler of personally-unfamiliar design, but should not do so out of hand. The now-white-with-orange-lettering book explains the test requirement and process; a club may have some additional requirement such as the owner providing an adaptor to fit its test-pump hose. The point would be to talk to the club's boiler-examiner first. He or she is likely to want to see the shell-strength calculation (a simple formula), and to inspect the work as it progresses, but there is nothing inherently novel about the Cornish Boiler design. The sticking-point might be the flue strength at that diameter - heavily dependent on diameter, length, roundness and pressure, and very hard to calculate - and I would suggest no more than about 30-40psi WP and a wall thickness no less than 3mm as a start. I though the idea is to run a Cornish-style engine from it. They used very modest steam pressures, and anyway a model version is not likely to be doing any significant work needing anything like even one kilowatt (well over 1HP!) of power. |
norm norton | 27/05/2022 15:57:53 |
202 forum posts 10 photos | Yes you are right Nigel, boilers can be approved, but the stress calculations are a science that only some seem to enjoy. Two kW of fire energy has to get through perhaps only 1% or 2% efficiency so it might be only 20 watts of engine power? Edited By norm norton on 27/05/2022 15:58:23 |
Christopher Jones 9 | 31/05/2023 01:32:40 |
7 forum posts | Thank you all for your advice last year. Having to go through 12 months of hardships (medical and career). I'm back in my workshop to pick back up. Having had alot of time to ponder and sketch I have decided that a horizontal boiler is must for my steam plant. I think we have established that coal would be a good experiment at present a full steam plant project is more important to me, so gas is not a must. A Cornish boiler for me has better eye appeal with the single fire box but the look of a gas burner on the front spoils the look. So or been playing with the idea of mounting the burner below the chimney pointing forward. This would in my mind require the flue to pass through the boiler twice to return to the chimney. A Lancashire boiler would possibly suit this better with 2 fake fire doors on the front over the 2 flue pipes.
Essentially a U shaped flue. And a clean stokers area at the front.
I would very much like if you can all throw your thoughts at this. I do plan to draw this up over the weekend and will post pictures.
Thanks in advance.
Chris |
JasonB | 31/05/2023 07:42:52 |
![]() 25215 forum posts 3105 photos 1 articles | If you bring the gas into the burner at an angle then it will only stick out about 30-40mm so you could just have a false backhead to cover that and then use a non return flue and chimney at the far end |
fizzy | 31/05/2023 09:22:10 |
![]() 1860 forum posts 121 photos | sweet violet 3.5 gauge loco uses an boiler which is essentially a cornish boiler modded for a loco. It would be very easy to alter the design to a pure cornish shape and shorten it. Od is 6£, id is 3.5" and runs on coal. If you go to my fb page, pendle steam boilers, go to photos and fourth row down there are some pictures of me making one to give you inspiration! Its a very simple build. Mine has been modded to run a mill engine with two inch bore, three inch syroke with an elleven inch flywheel four inches wide. This was not a commercial project but was and is an ongoing build for pleasure.
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Boiler Bri | 31/05/2023 10:13:17 |
![]() 856 forum posts 212 photos | Paul,
That link was just what i was looking for.
Brian |
John Hinkley | 31/05/2023 13:05:51 |
![]() 1545 forum posts 484 photos | And if anyone fancies building a full-size one, here's some info/dimensions from which to build it. Might even be of use once scaled down: John
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vic francis | 01/06/2023 05:34:20 |
125 forum posts 21 photos | Hi Chris have sent you a pm regards vic |
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