Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines
Builds, Repairs, Show Your Machines! => Technical Tips, Builds, and Help => Topic started by: Jim on July 07, 2024, 08:57:29 pm
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Thanks Raphaël, appreciated!
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Bonjour Jim,
My experience is based on a Yarrow boiler I bought : https://youtu.be/5h-gJeoZH3U
A small boiler is quite difficult to manage because the fire remains atscale 1 and I think your one is quite larger than mine.
If you are able to create the heat, it is not stable, it rises very high and falls very quickly. This means that the brazing must be perfect and made with a more resistant material than the classic silver mixtures used on our gas boilers.
Brass does not like strong variations in heat, stainless steel is very difficult to work with, copper remains the metal suited to our scale.
Besides this, I have very skilled friends who have been able to install such a boiler in a launch, example :
https://youtu.be/mwwgy0qGKoA
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Thanks for the photos Arnold, much appreciated!!!!
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I have never built a coal fired boiler, but am aware of some properties of burning coal (from a little bit of blacksmithing) that will need to enter into your thinking about building such a boiler.
First, you will need to provide some form of positive draft to get it going when first firing off. It is a rather slow starting fuel, and until it gets going well enough to create its own draft, it will need some help.
Next, it can burn really hot, so you will want some form of liner within your firebox that keeps the fire from direct contact with the outside surfaces, or they may well start glowing orange, and depending on what they are actually made from, even start losing shape, sagging or outright melting.
To follow on from that previous thought, pick your construction materials well as they must be suitable for high temperature operation, especially your fire gratings, which must be open enough to allow plenty of air passage, yet small enough that your coal doesn't simply fall through.
Following that last thought, you also must provide some form of catch tray under your fire gratings that is also capable of catching very high temperature glowing embers that will continue glowing hot for some time to come after dropping through your grate. It must also be easily removed and dumped when necessary.
You will need to design the whole setup such that you can directly access your flues, so they can be brushed out occasionally, as coal often leaves fairly thick deposits that will interfere with proper heat transfer of future firings.
Hope any of that helps with your thinking about this project, but I also hope it doesn't discourage you any. We would all love to see whatever you come up with along these lines. Certainly, it has been done a million times before, you just need to get the right info from the right people so that you can get it done the right way!!!
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Here I made some pictures of a vertical boiler - it was made in England by a company
named: Bischop-Ellis from Burmingham
Unfortunately they are out of business - they where specialized for locomotive boilers
all in copper and silversoldered. Top quality.
My boiler is mounted on a plate together with a Stuart Nr. 9 steam engine, a dynamo,
a Stuart steam pump and a line of little lamps. It makes fun to run it on steam/coal
old video: https://www.youtube.com/watch?v=x5NWraC33Po
Arnold :D
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Arnold, thanks for the pics.
Would you happen to own a vertical coal fired boiler?
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I never made one but I have some - problem is you can run them only
outdoors and they need a lot of time to heat up. Preferable you have
to fit a ventilator to the chimney. Here is my biggest horizontal model
Arnold
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Thanks Charlie, I've been watching some Youtube vids.....but first hand knowledge is always great.
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Not me Jim.
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Anyone constructed a coal fired boiler?