Western Soft Coal Experiments in the DF 520

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stoker-man
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Post Wed. Mar. 10, 2010 7:09 pm

We are testing bituminous coal from the West. This first test is with Wyoming bituminous from the Gillette area. The video shows a fire with an air setting of 2 and a feed rate of 10. The short worm and bin cannot be used. Reducing the air to 1 stops the smoking.





The picture shows the coal sample sent. The coal is much too large and had to be broken down to the size in the middle pile. The last sample, opposite the Wyoming coal is anthracite rice.
Lignite experiment 006.jpg

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Post Mon. Mar. 15, 2010 12:23 pm

Burned by volume 19 gallons, by weight 83 pounds of Wyoming bituminous. The ash weighed 4.5 pounds and the volume was 1 gallon.

By weight or volume, the ratio of raw coal to ash was 5%

The largest clinker was 2x2x 3/4" thick. The heat output is more than wood pellets and maybe 60% of anthracite. The fire burns with very little smoke at the chimney; almost imperceptible. The size of the coal was buck sized, down to dust.

The coal that was the size of chestnut upward to stove coal burned great in the hand fired boiler. I got a 12 hour burn, no clinker at all, and ash was the same as wood ash. If I could get it in bulk, I'd use it in my own boiler.
Wyoming-soft-coal-clinker.jpg

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Sting
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Post Mon. Mar. 15, 2010 12:56 pm

Does this mean your ready to sell a Bit consuming boiler?

Or are we still fiddle - diddeling around?

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Post Mon. Mar. 15, 2010 2:20 pm

It means that the standard 520 burns soft coal and lignite in the small quantities that I have received, with no modifications necessary to the existing design. The coal must be properly sized and the proper size coal seems to be considered waste out West. Also, the heat output is significantly reduced by the lower BTU content of the coal; at least 40% less.

I'm still waiting for some coal from Colorado and Alaska.

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Post Mon. Mar. 15, 2010 3:46 pm

Just came back form the post office, aproximatley 170 lbs, eight boxes of Healy Alaska's bituminous is headed your way, priorty mail, sized so you could put about three pieces on a nickle, not a penny :) . I hope it burns well, but I'm still hopping the EFM rotating ring is a viable option.

I like the room under your burner for ash removal, currently with my Will-Burt style stoker I lift some clinkers out and grab a few shovel fulls of ash, that inevitably contain burning coal, I've tried leaving the ash in as a Iron Fireman instruction manual recomended but it just fills the combustion chamber and causes preasure in my coal hopper. I understand both the rotating ring and the standard DF 520 have room under the fire pot.

The coal data sheet from Usibelli coal mine web site calls for "initial deformation temperature (red) 2150 F" and a "T250 temperature 2320 F" near as I can tell the T250 temperature is when coal becomes a fluid and possibly flows into clinkers, I searched the web some with limited satisfaction. Anyone have some T250 numbers for the coal they burn :?:
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coal to EFM 004.JPG


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Post Mon. Mar. 15, 2010 4:27 pm

Did you see the youtube video link above? There is no sizable clinker to remove. I'd like to have enough coal to test so I can see if the ash ring builds up higher and higher instead of falling off. It might be necessary once a day to manually push the ash off the ring if that happens. The clinker is so fragile that finger pressure breaks it apart.

We are sending out the AF150 Furnace this week and that will be appearing at various shows in Wyoming and surrounding areas.

The coal that shortbus is sending should be perfectly sized.

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Post Mon. Mar. 15, 2010 5:38 pm

the rotating ring adds a measure of safety to the boiler; it prevents a massive clinker from forming, breaking things, filling the firebox, or causing an outfire. The rotating ring, while not necessary on very high AFT coals and proper burning conditions, and short burn times, will prevent the chance of any of the mentioned bad things from happening under conditions and coal suppliers other than the ones you've tested under. lignite I wouldn't be concerned with, but before a boiler is sold as a "bit burning" boiler using the origninal anthracite pot without the ring, extensive testing has to be done under varied conditions and load and over longer periods of time, or you may have some very displeased customers.

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Post Tue. Mar. 16, 2010 7:52 pm

Yesterday before I went home, I went to empty the coal container and then crank the rest of the coal in the auger into the pot. The coal bin was empty for some time and the fire bed was half way down into the pot, at most, a quart of glowing coal, so I shut everything down and called it a day.

In the morning, I wanted to see if there was any clinker on top. The only ash on top was talcum-powder-like and I stirred it around with my hand. Added fresh coal to the bin and cranked it into the pot until the pot was full. To my surprise, I saw a few red coals in the mix, turned on the air and the pot came back to life after 17 hours of inactivity. I then remembered Joe saying the same thing when he tested in Shenandoah. (That unit has been in use the entire Winter at Sheridan, WY, heating a 7,000 sq. ft. space and has not had any problems at all). I had burned a total of 12 hours, (7 hours and 5 hours continuously,) about 35 gallons worth when I took the video below.





We found a breaker in Montana that will properly size this soft coal from the Powder River Valley of Wyoming, which is the only type of bit coal that has been problem-free in our stoker at this time. The warm air furnace will be on display at the various shows in Wyoming starting soon.

Unless something changes, there is no reason for a rotating ring using the coal from the Powder River Valley. The clinkers are smaller than Anthracite and much softer. The fire held for 17 hours without any forced air, so I'm not concerned about outfires. The further testing with a furnace will begin in Wyoming in a few weeks. The unit will never be advertised as a Bit Burner, but the existing Sheridan stoker has run all Winter on bit without any problems.

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Post Tue. Mar. 16, 2010 8:19 pm

stoker-man wrote: (That unit has been in use the entire Winter at Sheridan, WY, heating a 7,000 sq. ft. space and has not had any problems at all).
Good woork! The tests look promising. Ok, you got my attention. Now, if the 520 gets certified for Bit, especially W.V. Bit, I'll be getting one. I have to move to Western North Carolina this year, and will need something that can burn the readily-available local black rocks :D

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Post Thu. Apr. 01, 2010 11:16 am

A breaker in Montana has supplied us some rice coal for the Wyoming market, but there is some more work to do. About 35% was pure dust, and a very low percentage was oversized, just enough that it might bridge over the worm. I'm going to put the oversized in the bottom of the bucket as a whole and see if it feeds. Otherwise, if a second screening can remove the dust, we might have some usable rice coal in bulk quantities.


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Post Thu. Apr. 01, 2010 12:39 pm

that's what will be almost impossible to find other than perhaps with this one dealer that's selling it; "rice" sized bituminous coal. that's going to be what keeps it from moving into the bit market.

btw, short bus, the reason you have so much loose ash is because your coal has a fairly high AFT. it won't clinker like the stoker was designed to, especially not at low load conditions. Many people seem to have the misconception that a clinker is bad - in some appliances it surely is - but in a hearth-set underfeed stoker a proper clinker just outside of the retort is ideal. A clinker allows for a huge reduction in ash volume, ease of removal and handling.

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Post Thu. Apr. 01, 2010 3:00 pm

Since I posted, I put all the small amount of oversized coal in the bottom of the bin and the rice over top and all of it fed in, so I guess that wasn't a problem. Then I dumped in half a bucket of pure dust and that fed in as well. So, I guess the coal from Montana will be fine, but I'd be happier if it didn't have the dust.

On Monday, I'll dump a full 5 gal. bucket of pure dust into the bottom of the bin and see what happens. The only problem with the dust would be if it was damp and it would bridge over the pipe's entrance.

As usual, there is no ash to speak of.

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Post Tue. Apr. 06, 2010 8:10 am

I dumped in a 5 gal. bucket of pure dust as planned. It fed well and burned, but it was a cool flame and smoky. As supplied, with the various sizes mixed , I'd say it is acceptable, but would be ideal if an extra screening was done to remove the fines.

For the first time, I left the coal fire continue overnight and everything went well.

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Post Fri. Apr. 09, 2010 7:55 am

Update: It's now Friday morning, 72 hours after all the coal in the bin was gone and I go to crank in some anthracite to fire up the boiler and the Wyoming coal is still red in the pot under the ashes. Turned on the air and it took off again.

I don't think a timer is needed for this coal.

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