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Running coal fired 5 steam engine on gas

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Kevin M28/05/2018 20:46:43
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2 photos

Hello,

that may be a stupid question, but is it safe to run a coal fired steel boiler on gas using a portable gas stove under the firebox? I was under the impression that gas gets hotter than hard coal, because it has a blue flame but that is not the case, is it?

Thank you!

J Hancock28/05/2018 21:44:21
832 forum posts

Safe ?

You have to remember it is gas you are using here, if the flame goes out and the gas keeps going ..........

what happens next depends on how far away you are.

Kevin M28/05/2018 22:06:03
5 forum posts
2 photos
Posted by J Hancock on 28/05/2018 21:44:21:

Safe ?

You have to remember it is gas you are using here, if the flame goes out and the gas keeps going ..........

what happens next depends on how far away you are.

Thank you, but I was asking if its safe for the boiler and firebox.

not done it yet28/05/2018 23:24:57
6733 forum posts
20 photos

Under or in the firebox? Internally, one would definitely need a flame failure device, I would suggest.

I have seen the effects of igniting fuel mixtures in confined spaces. The uncle of a friend was killed about 40 years ago while relighting a furnace after the Christmas break.

An idiot, who should have been watching a gas/oil flame in a kiln left the job and the flame went out. Luckily there was no explosion on that occasion. The kiln had just been completely relined with refractory bricks at huge expense. The electrostatic precipitators were hurredly de-energised and the kiln was well ventilated before attempting to relight the flame! It probably cost us two hours, or more, at a time of tight production reserves, but could have been a disaster.

Another instance was that of an auxiliary firing fan casing, that exploded because there was a fire in the coal store and burning embers were entrained in the air flow. Before the incident, some workers congregated around that particular fan on cold days or nights...

Be very careful, is my advice.

Another JohnS29/05/2018 02:07:53
832 forum posts
56 photos

Hi Kevin;

By Gas, I'll presume you do not mean the American/Canadian "Gas" as a word for Petrol.

"Over here" propane firing is quite normal for steaming at many clubs. Some tracks (e.g. Train Mountain) you can't use coal due to fire hazards.

Now, the only direct experience on models is that I've built a propane burner for a 3-1/2" gauge locomotive from the "Raritan" design, but have not fired it up yet. (Bill Moorewood designed the locomotive and burner). Maybe now that the nice weather is here, I'll give it a try.

The Winnipeg group, the one and only time I was there, were all propane, from what I recall. I brought along my coal-fired Tich (3-1/2" gauge) and was thought to be a bit strange, I think!

I "cut my teeth" on full size steam on an oil-fired pacific, about the same size as your A4 (But, not nearly as fast!) Oil firing of full size was very popular on certain roads/areas, due to lack of coal, abundance of oil, and especially fire hazards.

Do some more digging - see what the Americans do, google for "Marty Burners", and see what you find. The information will be out there.

JasonB29/05/2018 07:00:05
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A gas stove won't give a very good heat output you would be better off with purpose made burners. Also unless the boiler is designed from the start for gas firing it may not be that efficient as the tube sizes should be altered and you don't get as much radiant heat through the sides of the firebox into the water legs, it all tends to go along teh tubes.

Properly designed it should not harm the boiler running on propane.

This is the type of burner that is often used made up onto a manifold to hold as many as you need, each gives about 5400btu

 

Edited By JasonB on 29/05/2018 07:41:43

J Hancock29/05/2018 08:08:25
832 forum posts

Safety aside, the objective to achieve, is to use the gas to heat a block of ' thermal material' to incandescence

inside the firebox. Everything else follows from that.

Ady129/05/2018 08:49:57
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5065 forum posts
734 photos

So a form of hot bulb/glow plug system would help make things safer, in theory

Kevin M29/05/2018 09:20:31
5 forum posts
2 photos

Thanks all for your answers. I appreciate every one of your answers.

I got a lot of mixed answers about mostly general usage of gas. I think I wasn't clear enough, so I will clarify some stuff. Sorry about that!

I want to use a propane/butane powered portable gas stove

(such as this: https://www.ebay.com/itm/3500W-Portable-Gas-Stove-Butane-Propane-Burner-Fit-Outdoor-Camping-Hiking-Picnic/322769488346?epid=8011435743&hash=item4b268f89da:g:syAAAOSwqF9ZxIBX).

I would put it under the firebox to get some steam in the boiler for a steam test. ( I don't want to run it on the track on gas!). I don't own a house and garden and a coal fire is stricly forbidden on our balcony, so instead of driving to my local club track everytime I could maintain and test the loco on my balcony using a gas fire.

Now, my initial question was if this is a safe methode for a boiler that was made for coal firing. I was not asking about the general saftey of gas. I'm not familar with the temperatures of a propane/butane fire or hard coal and melting temperature of steel so my second question was if the propane/butane fire gets hotter than a hard coal fire? I really don't want to melt my firebox!

Thanks all.

J Hancock29/05/2018 09:28:24
832 forum posts

My best guess, absolutely fine in that application BUT do not expect it to make steam at anything more

than a rate to maintain a running tick-over, maybe less.

JasonB29/05/2018 09:51:58
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Will be OK for testing but as said you may well have a job getting it to boil, that stove at best is equal to two of the burners in that video, some engines use 20 of them. Decent sized propane torch would put more heat up it.

Kevin M29/05/2018 09:54:57
5 forum posts
2 photos

Thanks guys, very helpful answers! That's what I wanted to know.

Have a great day!

Nigel Bennett29/05/2018 10:18:01
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456 forum posts
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The late lamented David Beale in our Leeds Society built a 5"G Adams radial tank to the Kelvin Moonie design and ran it on bottled gas. David was a highly competent Engineer (with a capital E) and he eventually gave it it up as impractical and resorted to coal firing. I cannot now remember the problems that he had, but I am of the opinion that if he wasn't happy with gas firing, then it's probably best avoided.

richardandtracy29/05/2018 10:20:02
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Does beg the question, is it a functional test of the engine or is it a functional test of the boiler's ability to generate steam?

If of the engine only, then you could use air to pressurise the boiler.

Using gas to heat the boiler, from the heat intensity and corrosive products of combustion point of view, it should be less bad than coal firing the boiler.

Regards,

Richard.

JasonB29/05/2018 10:24:31
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Posted by richardandtracy on 29/05/2018 10:20:02:

Does beg the question, is it a functional test of the engine or is it a functional test of the boiler's ability to generate steam?

 

Answered above "I would put it under the firebox to get some steam in the boiler for a steam test"

Edited By JasonB on 29/05/2018 10:24:48

norm norton29/05/2018 10:56:20
183 forum posts
9 photos

Kevin

As has been said above, without seriously big burners, and a large bottle of propane, you will struggle to get enough heat into the boiler to produce useful steam.

A "Steam Test" for official purposes requires a full coal fire, with full blower, to check that the safety valves can release all the steam produced.

If you want to test your boiler for minor leaks and is the pipework ok, etc. then make up a water hand pump, valves and gauge and then hydraulically test at the boiler's normal working pressure.

If you want to test the cylinders and running motion then get a compressor that can shift at least 4 cufm.

Norm

Andrew Tinsley29/05/2018 11:19:56
1610 forum posts

Why not use oil firing? Plenty of full size locos used it and it does work on smaller locos.

Andrew.

duncan webster29/05/2018 11:23:37
3922 forum posts
61 photos

Jason's video shows why it is not easy to get a gas fire to burn inside a firebox. If that very tall flame gets into the tubes it will go out, leading to incomplete combustion and sooty tubes. However it obviously can be done as our USA friends have shown. The model gas turbine guys burn a vast amount of paraffin in a small space, but they are under pressure which I think makes it easier. I'd be very interested in an authoritative article on the subject.

richardandtracy29/05/2018 15:14:17
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943 forum posts
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Posted by JasonB on 29/05/2018 10:24:31:
Posted by richardandtracy on 29/05/2018 10:20:02:

Does beg the question, is it a functional test of the engine or is it a functional test of the boiler's ability to generate steam?

Answered above "I would put it under the firebox to get some steam in the boiler for a steam test"

Not everyone uses the same version of English & may be using the words differently. It does no harm to check understandings are the same, particularly on a board where there are international contributors.

Regards,

Richard.

SillyOldDuffer29/05/2018 16:01:44
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As most carbon based fuels burn in air at roughly the same temperature (about 2000C) , I doubt propane would get much hotter than a coal fire. From my armchair I don't think gas heating a model boiler would be unsafe unless you did something silly like letting the room fill with gas before striking a match or attacking it at a point with oxy-acetylene.

For a test, OK. Trickier to get the best out of gas or oil in a model loco boiler I suspect, a different firebox design would be needed. With gas there's no mass heating the firebox - it's all flame. In a conventional model locomotive I'd guess quite a lot of steam is generated by the mass of hot coal in contact with the firebox not just that made by hot gas playing on the tubes and boiler skin.

A full size firebox includes a few hundred kilograms of white hot firebrick arranged in an arch. Mainly to improve combustion it also retains heat rather than blowing it out the chimney. Never noticed an arch in a model locomotive firebox; on a small scale are hot coals alone sufficient to do a decent job?

LBSC famously proved that spirit burning boilers weren't the last word in model boiler design. Did he finish the job though? I can't help feeling that a modern analysis would provide better design guidance and improved boiler performance.

Dave


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