Keeping the fire Going

[Builder01]

I finally have things on my locomotive to the point that I can put coal in the fire box! It is a 1" scale loco with a "between the frames" firebox. The grate is 5-3/4 inches by 2-1/2 inches.

Since I do not have a track at my house, I have made a "rolling road" to do my steam test, so, Saturday I tested the locomotive on it's own boiler. Things went pretty well. I have a Tee in the plumbing so I can use it's own blower to induce draft to raise steam. No "blower" on the stack. This seemed to work quite well, at about 40 psi, the "house air" can be disconnected. Raising steam and getting the safeties to lift is no problem. Working pressure is 100 psi.

I am using anthracite rice size coal. It seems like the perfect size for my grate. It is slightly larger than the spaces between the bars. The down side is, it is also quite difficult to keep lit! I keep the blower on just a little bit all the time. I start the fire by using charcoal soaked in kerosene. There are probably other ways, but, this was suggested by some of the books I have read and it seems to work pretty well. After the charcoal is burning well, I gradually add the coal.

The anthracite I have, once it gets going, seems to "weld" itself together into one big lump and chokes the air supply from under the grate and eventually extinguishes itself. Is there a different way I should burn the coal to prevent this? Am I adding too much too soon? Should I look for some bituminous to mix with the anthracite? What other suggestions would others have to keep the fire going?

Thanks,
David

[Dave Bortz]

Hi David;
Anthracite requires a lot of air to burn it... if you leave it cool by closing off draft, you'll be on a siding for a while looking for some way to get it going again.

I would recommend finding a source of soft coal and testing your loco on that for a while to get going, or at least mixing the two for a ratio that works for you and your loco.

One of the best steaming locos I ever ran, had a narrow firebox that was deep, and several tried, but none could get it to burn anthracite. There was a reason Wooten built wide, shallow fireboxes to burn hard coal on the Reading...

Give some good, hi-volatile, low ash, less than 1% sulfur, soft coal a try, and you should be happy with the results... we also start off with charcoal, but don't be premature as a charcoal fire won't sustain the steam generation required for running the loco (at least our locos won't run on charcoal).

Note, this process can take a while until you find the right mix of everything. Don't be discouraged...
Let us know how you make out...
Dave

[Bob D.]

Good anthracite shouldn't be sticking together at all. Thats what soft coal tends to do. I think rice is too small. Not getting good air up thru the coal when it is fine. Pea size might be better. Keep the fire thin and feed often but not more than a scoop or two at a time. Using natural chunk charcoal and not pressed brickets to start the fire is better too.

Bob

[Builder01]

Hi Dave,

Yes, to be clear, I keep the blower on just a little bit all the time, at least in my now one time experience! I can just crack the fire door to peek in at the fire to see what effect the blower has on it and it really seems to be doing the job well.

I'm leaning towards experimenting with some of the soft or "semi-soft" coal. Looks like it is easily purchased off Ebay. Only anthracite is locally available.

So, why was the anthracite "welding" itself into one mass to such an extent to completely choke off the air? Too much additional coal too soon?

I look forward to a few more responses. I would like to do more experimenting with what I have this coming weekend. I would also like to try small wood pieces soaked in kerosene to start the fire. Currently, my garage smells like charcoal briquettes!

David

[Builder01]

Hi Bob,

The coal I have is hard anthracite for sure. Not only does it say it is on the bag, but it seems to be very hard and quite shiny. I think these are the qualities of hard coal? But, you could be right, maybe it's just too small. The fire hole is only 1-1/2" I.D. so, my shovel is only 1-1/4" O.D. The coal cannot be too large or it won't fit through the door.

One thing I forgot to mention is that the grate is a sloping type. At the tube sheet end it is about 2-1/2" inches from the top of the grate to the bottom of the first row of flues. At the fire hole end, the grate is about 1-1/2" below the fire hole and is flat for a few inches before it slopes. Can the slop be used to my advantage? Or, is a sloping grate more of a problem?

David

[Glenn Brooks]

Sounds like your biggest problem is the anthracite. Switching to bituminous would show a major improvement in your burn rate and steam production. In full size loco's in the old days, anthracite loco's were specially design fireboxes with much larger grate areas than more universal bitunimous boilers. I think you are fighting a loosing battle with the small physical size of your firebox. Borrow a bucket of Coal from some one and experiment. I,think you will be pleasantly surprised at the result.

P.S. For 3/4" scale You can always crush coal to the desired size. Sounds like 1" minus chunks might work well for your physical dimensions.

Happy steaming!
Glenn

[Builder01]

Hi Glenn,

Thanks for the response. Raising steam does not seem to be a problem. Getting up to working pressure and raising the safeties does not seem to be a problem either. The coal becomes a single welded mass and then chokes the air supply and brings everything to a halt. I will for sure try some of the softer coal as well as larger pieces. The anthracite I am using is actually very small, about 3/8" or smaller pieces. Which seemed correct for the grate. Perhaps they are small enough to start to block the air supply. Initially it does work very well. The anthracite burns very hot and brings things up to working pressure quickly. Then, the air becomes blocked and the fire pretty much kills itself.

You think 1" chunks would be more appropriate for my fire box/ grate? I have absolutely no guide or reference for what to use. At one inch size, I could only fit about 8 or 10 pieces!

I will experiment more this coming weekend.

David

[Glenn Brooks]

Hi David, indeed perhaps 1" is to big. Take my comments with a grain of salt regarding coal size, as really my direct experience is really limited mostly to 2" scale equipment and up- with 12" x18" coal grates. So big chunks of coal were OK there, but perhaps not so much with the finer size you are working with. If you can work out a way to grind or crush some coal samples to several different sizes, I am sure you will be able to settle on an ideal size for your loco. Plus you have the distinction of being one of very few people who have actually run with anthracite !

Now, regarding coal size, here's a short story from last weekend. One of our local tracks ran their opening day public run last weekend. One of the loco's in attendance was burning some nice grade Utah bituminous. He was using 1/2" to 1" minus coal in a fairly small and narrow fire box -although 7 1/2" ga, so probably twice the grate area of your loco. He was able to bank up a fairly thick fire with 1" bituminous and run almost continuously with the fire burning through the layers quite well. I looked at the fire several times and saw a coal bed maybe 3 lumps thick at times. However with bituminous, and a bit of blower whilst in the station, the fire would burn through the bed without problem. I would say he also needed to break up the clinkers and keep a clean hot bed throughout the firebox and more or less regularity rearrange the fire-maybe once each run around the track, while new passengers were loading.

Iam trying to remember what I learned many yeas ago regarding anthracite. It's been a long time and I always burned bituminous, so I find my early research has pretty well faded into the mists of time... Maybe someone in anthracite country will join in with some key bits of knowledge. I would say clearly what you are esperiencing re: the anthracite fusing together and killing the fire is certainly a characteristic of the coal type - otherwise it wouldn't do it! I vaguely, vaguely remember reading similar comments that anthracite fires were at risk of clinkering up, hence needed a wide fire, spread thin to burn, possibly/probably due to the caking and fusing problem you describe. Anyway the coal type does indeed burn hot - as you have observed. However the inordinately larger fire box size needed with anthracite locomotives May be a permanent problem with your 1" scale loco. Overall, I suspect you will be happy with your test of bituminous.

Let us know how it turns out!

Glenn

[Bob D.]

David,
All the ”rice" sized coal I'ved dealt with is actually about the size of real rice. Generally used in auger fed stoves and furnaces. Hard and shiny is typical but the fusing together when burning certainly is not. I have seen mismarked bags plenty of times between nut and pea coal but it was at least still anthracite. I burn straight anthracite in my 1 1/2" Camelback and it does have a Wooten firebox. It requires a different technique in firing than soft coal. The lack of smoke and ash out the stack is nice. Steams very well.
I have quite a few 3/4" locos. It's pretty tough firing them on straight hard coal and I have really worked at making a go of it. The tiny fireboxes are not very forgiving. The small flues soot up fairly quick with soft coal which is what I ran for a few years until I got a large supply of Welsh steamer coal.
With the coal you have, try being more aggressive with a poker to keep it broken up. Generally with anthracite I rarely stir it up as it is an easy way to kill the fire, but with what you have it sounds like you need to. Track down some other coal to try. Some hardware stores carry Smithy coal which is soft or find a blacksmith.
You've only fired once. It takes experimentation to find what works. Thats part of the fun!!

Bob

[Builder01]

Hi Bob and Glenn,

Thanks again for your responses.Yes, I will continue to experiment. As you say, I will eventually get the right combination. I would like to successfully be able to steam in my driveway before bringing it to the club track! Thanks again for all the suggestions.

David

[Kimball McGinley]

I would also think that when actually running under load at the club track you will have much stronger draft from the steam exhaust than when just spinning on rollers? That might really change the way she steams. Can you add some drag so she barks a bit?
A car engine revved to 6,000 rpm in the driveway is just loafing compared to 6,000 rpm getting on the freeway with that throttle actually wide open... Just ask my wife!

[Builder01]

Good point! But I'm not sure that the draft is the problem. Initially, I can take the boiler right up to working pressure and lift one or both of the safeties, no problem. If there was not enough draft, I probably could not do that. What happens is that the coal starts to fuse together into a single mass, or, several small masses, effectively blocking the air. Would more draft reduce this? Maybe, not sure about that. If I can rig some way to "load" the engine, I can certainly try that and see what happens.

I think my next move is to try some softer coal. While I wait for the softer coal to arrive, I'm going to experiment a bit more this weekend with the coal that I have.

David