Author Topic: 3 inch boiler build  (Read 7469 times)

Offline Ye-Ole Steam Dude

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Re: 3 inch boiler build
« Reply #165 on: October 10, 2018, 10:06:38 AM »
Hello Gary,

Very impressive and a job well done.

Have a great day,
Thomas

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #166 on: October 10, 2018, 12:25:16 PM »
Thank you all three   :)

@ MJM460 - lots of good information and advice there for me to consider. Am pleased that meths isn't considered second-rate - firing the boiler on it gave me a good feeling! Interesting point about that gap between burner and boiler - I think it warrants further exploration... though I'll probably aim to close it once the thing is properly assembled.
On the burner casing - yes, I have several modifications in mind for this - the way it is presently is just a start.
Good idea re a more controlled steam test. I had assumed that I'd need the pump connected up for that (which it will be, but isn't permanently connected yet), but I can see now that that isn't strictly necessary as long as the water level is kept an eye on.

@ Peter - will keep an eye on th flame colour. Indeed, the flame seemed clean enough, albeit yellow in colour. Very little soot was formed.

@ Thomas - cheers  :ThumbsUp:

Offline Kim

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Re: 3 inch boiler build
« Reply #167 on: October 10, 2018, 02:36:17 PM »
Very interesting test, Gary!
Thanks for sharing your experiment.
Kim

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #168 on: October 10, 2018, 05:42:03 PM »
Cheers Kim, and thank you for your interest.

gary

 :ThumbsUp:

Offline MJM460

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Re: 3 inch boiler build
« Reply #169 on: October 11, 2018, 12:03:22 AM »
Hi Gary, the heating value of Meths is about 26000kJ/kg, only about half that of other hydrocarbon fuels such as propane and butane, so you have to burn more of it.  It is a less intense flame, you could never silver solder with it, but not too severe on a small copper boiler and not too hot means most unlikely to damage the boiler.  Probably not the answer for a passenger carrying 5 inch gauge loco, but more than adequate and very safe for running a small small engine.  Even those small gauge locomotives such as run by Zephryn and Paul, so well loaded for their size.  My engines are 12 mm bore with 12-16 mm stroke double acting and my small burners and boilers run them at up to 2000 rpm by my digital tacho, so more than adequate I feel.

A good source for a commercial burner is the Trangia stoves used by hikers.  (Not the ones sold as warmers for food dishes, which tend to be too gentle.). The whole outfit with cooking pans etc is expensive, but light weight for hikers, but the replacement burners are quite inexpensive at hike equipment shops.  Ideal for your vertical boiler.  Looking at the full kit will give you ideas for making the firebox, with air holes near the base below the flame, and how much height they allow between the top of the burner and the base of the cooking pan.  One fill of 30 -50 ml will raise steam and give 10-15 minutes run time if you insulate the boiler.  Obviously you will need to make something with a separate tank if you want to run for a lot longer and use your feed pump.  Otherwise, when the fuel runs out, top up the boiler with the pump, refil the burner, and you are soon away again.

MJM460
The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #170 on: October 11, 2018, 06:44:01 AM »
Hi MJM.

The more I hear about meths, the more I like it!

Funnily enough I had toyed with the idea of adapting a camping stove. Is it something like this that you mean?

https://www.amazon.co.uk/Trangia-Spirit-Burner-with-Screwcap/dp/B000AR7970/ref=sr_1_1?s=camping-hiking&ie=UTF8&qid=1539235735&sr=1-1&refinements=p_4%3ATrangia

If so, what would be the advantage (if any) over a home made burner with a cap with say four wicks held in brass collars?

Thanks for your input.

gary

Offline MJM460

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Re: 3 inch boiler build
« Reply #171 on: October 11, 2018, 08:33:33 AM »
Hi Gary, yes, that's the one.  The advantage is that ring of little holes around the opening.  When the unit heats up, the Meths in the bottom starts vapourising, and the burn switches from gentle flame in the middle to little tongues of blue flame from each of those holes.  I suspect a bit hotter than a wick flame.

MJM460
The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #172 on: October 11, 2018, 12:19:22 PM »
OK thanks - will bear it in mind.

Cheers,

gary

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #173 on: October 16, 2018, 11:15:37 PM »
Well, not such a successful day today.

My tests of various firing methods continue. Today I tried wood - small pieces of bone dry hardwood in fact.

Because the boiler is small and only has five tubes, I reasoned that a large, tall, bell-shaped firebox would funnel the heat up into the boiler and compensate for any lack of draw. I rigged up a rough version of this out of a couple of iron and steel water pipe ends and connectors that I had scavenged from a skip some time ago.

I don't have an electric blower but I did use a small blowpipe to enliven the fire ('inspired by the 'boufadou' as used in France instead of bellows). I now also have a steam blower fitted to the boiler.

The arrangement was not a success. The tall firebox only served to hold the boiler too far above the heat. Lack of ventilation led to a situation in which the fire would blaze with the blowpipe on it but would dwindle as soon as I stopped puffing. The steam blower tugged valiantly at the fire but ultimately there was just not enough heat getting to the boiler.

This is not a major problem as the boiler has already performed heroically on both gas and meths. However, I would also like to be able to run it on wood, coal and charcoal if possible, so I will persist. This evening I began radical surgery on the firebox in an attempt to fix the above problems. The next firing will see the boiler sitting closer to what should be a hotter fire, and I may use charcoal for it.

That could be some time away, as I'm going away next week and when I come back I'll have to temporarily shift focus on to other projects from early November up to Christmas, as there are a couple of special presents I plan to make.

None of this seems to happen quickly...

gary

Offline Gas_mantle

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Re: 3 inch boiler build
« Reply #174 on: October 17, 2018, 12:03:21 AM »
Gary,

Could you try with softer 'splintery' wood that may burn easier? I think in relatively small quantities hard wood might be difficult to burn well enough.

Before I bought an electric blower I used my Hoover close to the chimney!  It works well but don't get too close with the hose as it sucks red hot embers into the Hoover body  - I'll leave you to figure out how I know that  :Doh:

Offline gary.a.ayres

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Re: 3 inch boiler build
« Reply #175 on: October 17, 2018, 06:31:56 AM »
Peter -

you may be right about the wood. Thanks for the tip. I'll continue to experiment with various forms of solid fuel but I think the firebox modifications are required anyway. The boiler looked good on the tall firebox - kind of Middle Eastern, a bit like some kind of sheesha pipe that you see guys smoking outside Lebanese cafes on Marylebone High Street - but it was just too far above the fire, so the top part of the firebox shell was in the lathe last night, getting sliced down to a less imposing size.

I'm not 'drawn' (no pun intended) to electric blowers, and if I find that I can't do without one for solid fuel, I'll probably just opt for meths.

I had a similar experience with our vacuum cleaner - I hoovered up a red hot ember from our woodburner. We still have the same vac, as my untidy-looking silicone repair on the plastic housing has held good for several years   :Mad:  :)

gary