Charcoal from the stove

[jayco]

I have an old pot-bellied stove in my shop for heat during the winter months.
Since I burn a considerable amount of firewood in it.....and I also like to make my own charcoal for the forge........why not sift the ashes from the stove and use the charcoal in the forge?

The 'problem' is that the stove leaves little charcoal behind........99% of what goes in the stove becomes ash.
This type of stove is not very airtight at all.......this one has no gasketing.

It's almost the opposite of what is required for the making of charcoal.......a well sealed barrel to keep as much air out as possible.

So, the question is, are there any easy modifications that would allow me to get more charcoal from it?

I can always burn wood in a barrel outside and make charcoal.Just thinking maybe I could get the old stove to do 2 things at once......

What does everyone think?

[rlarkin]

I think the problem you would face is that to generate heat, it needs to burn hot.
To make charcoal, it needs to smolder cold.
You would light it, get it hot, then choke it down to smolder and loose the heat, and the ability to get heat until you empty out the charcoal you made, which could take a day to truely work properly.

You might get a little heat from the smolder if you looped in a large diameter pipe and pumped air through it like a heat exchanger.
But during the times you used it for heat, you could possibly burn up your exchanger.

[easilyconfused]

I've done the same thing for many years in our shop stove. I just pull out the embers and smother them in a barrel once they're down to good embers. Gets kind of smokey and you want to make sure it's clear of any flammables in the area, have a fire extinguisher handy, and watch it for a while to make sure the fire is in the barrel not the shop walls. Touch wood I haven't had any issues with fires. Not much more risk than the forge itself if the proper precautions are taken. Something I'd try if I had time would be to rig up a barrel with a wagon to roll it outside in the winter. Much faster cooling that way and a lot less smoke in the shop. I always have the doors open to suck the smoke out too when I'm smothering it. My furnace is large enough I can get half a 55 gallon drum per burn and 2 burns through the day. When it's just smothered I start another fire while watching to make sure it's out and then go for lunch or supper while the smoke clears from the shop.

Full 55gal drum a day, which generally lasts the next day of forging when I'm on break. Shop stays warm too since the doors usually have to be open to keep it cool enough you're not sweating too much on a full furnace.

[craig]

I make charcoal in the stove a couple of ways...Both involve a small stock pot or something of the like (I used to use a coffee can but the pot is nice cause it has handles)
First method is to burn a bunch of wood until it's only charcoal left, then scoop it out into the pot and put the lid on until it cools.
Second is to cut the wood into small bits and fill the pot, then once your fire is going good, put the pot (with loose-fitting lid) in the stove and keep wood burning around the pot until no more flame is coming out from the lid. When it's really cooking it looks and sounds like a blowtorch !! Then take it out and leave it sit until it's cooled.
The first method is less work, but you have to deal with more ash.
Second method is more work cutting it all up, but the charcoal is nice and clean.
In the summer I use a 1/3 of a barrel on the fire pit (one of the two pics in my gallery)

[JohnW]

Hey jayco, in my opinion, you've analysed the problem correctly. The stove burns the embers to ashes, mostly. So I don't have any great ideas. Shovel out the coals and extinguish them by suffication or water -- work.

Some wood produces a big bed of coal easily. Yellow poplar does this. It seems to break apart before it gets all burned down. But ash, one of the world's greatest firewoods, doesn't seem to break up much at all. It just burns down to ash. (Ash to ashes.)

[LarryM]

Jayco,

One thing you can do to make your stove more air tight is to roll up lengths of tin foil into a rope like shape. Then use it as a door gasket. It works on my homemade wood stove. With door gasket it will burn all night.

Larry

[jayco]

John W,I have one idea to try......don't know if it would work........to simply shovel some ashes(possibly dampened) onto the glowing bed of coals in the stove at the end of the day.
I don't know if it would work, but an easy experiment to try.

Larry M, thanks for the suggesting of using tin foil........should be effective at sealing out excess air.......and much cheaper than buying a bunch of the 'rope type' stove gasket material.
Hmmm....would even be handy for sealing the lid on a charcoal 'burning barrel'!

[woodtick]

I get alot of charcoal from the stove in the way that JohnW already suggested. When there is a deep bed of coals in the stove, I'll take out a scoop full and give 'em a good spraying with a water spray bottle.

[Ice Czar]

there is a class of gasifiers that rely on a throttle body type constriction to allow the fuel to drop into a lower chamber once its pyrolyzed to charcoal

the trick there of course is a relatively consistent fuel stock
(rice hulls, wood chips, ect) and working out the amount of constriction required

typically the upper chamber is to create woodgas
(mostly CO CH4 H2 and tars )
while the lower chamber is employed to create producer gas with air
(2C + O2 → 2CO)
or in the event steam is injected, water gas
(C + H2O → CO + H2)

rather than a secondary combustion chamber
it could be a chute leading to a quench chamber

[bsiler]

I have an outside wood furnace that I use to heat my house. A lot of times when I clean it out there will be a good amount of hot coals that I take out. I use 2 large metal trash cans to store the ashes in until they are cold so I can dump them. I've noticed there is usually right much charcoal in them when I empty the cans. After reading these post it seems like I might have a supply of fuel.

I'm new at this and used coal a few times ( not counting the course I took). Does charcoal start the same way coal does and how long does it burn compared to coal. I have a forge I made myself with a champion 400 blower.

[jayco]

bsiler, I like charcoal as a fuel. It actually starts easier and burns cleaner than most coal that I have seen.
The big drawback is that it burns up quickly.
When I'm lucky enough to find charcoal in the stove, I just sift out the ashes and use it.

If I recall correctly, charcoal has about 1/5 the energy per volume as coal does.
Pound for pound I think they have about the same heating potential.
It's just that charcoal is somewhat lighter and fluffier than coal.

[bsiler]

Well, I tried some charcoal. It worked real good. The only thing I was a little worried about was the sparks when I cranked the blower. My forge is in a small log building that my great grandfather and my grandfather used as a blacksmith shop. I need to get me a fire extinguisher in there. It did burn up fast but so far I have not been able to spend very much time at the forge at a time.
Thanks jayco

[bsiler]

jayco
I've been saving charcoal from my furnace. At first I was just going thru it by hand. Not to good! You mentioned sifting yours. So I made a sifter with 1/2 inch rat wire ( I had seen somewhere in here where someone used 1/2 to sift through coke and left over coal). It works real good except there was a good amount of 1/2 inch size charcoal that falls through with the ash. What size sifter (or what do you use for sifting) do you use? I imagine the 1/2 inch size stuff would burn very quick, maybe not worth saving. I also have some big pieces. Should they be broken up to work any better.

Now that I've started saving it, I would not have thought I could have saved as much as I have in a weeks time.

Thanks for the thread, I don't think I would have ever thought about the charcoal from the furnace.
Thank You

[jayco]

bsiler, you mention fire danger from sparks in your log shop. yes, you do have to be careful of that........especially if you have horizontal beams/logs where sparks and hot scale can fly from the forge and start smoldering without you noticing.
I have some pieces of old roofing metal nailed to the wall behind my forge as a fire proof wall covering.
I always kinda 'check around' when I finish forging for the day. Large sparks can land on cotton gloves, your jacket, a cardboard kindling box, or your open bucket of charcoal sitting beside the forge and start a fire after you have left your shop.

As far as sifting the charcoal is concerned, I use 1/4 in. rat wire made into a little square tray ( the edges bent up) it looks like a cake pan.

The smaller stuff, 1/4 in. to 1/2 in. is burnable charcoal and I use it, but is not as clean as 1/2 in. and larger. If I'm going to forge weld, I use the larger charcoal.
I will resift to a larger size )(1/2 in. is a good size) for the good stuff........or just rake the larger pieces off with my hands.

Some folks use a piece of expanded metal ( the stuff with the diamond shaped holes in it) to make sifters. You can put a handle on a piece of expanded metal and make a sifting shovel.There's a B P on that somewhere.

Really large pieces of charcoal, I break up into smaller pieces.
1/2 to 1 in. seems to be about the right size for me.
Also, it takes much less air for charcoal....that will make it last a little longer.
Hope this helps....James

[belargehair]

Lately, what I have been doing is when I have a fire out in the back yard, I throw some chunked up wood in a cookie tin and place it in the fire pit. when I'm ready to go in or run out of beer, I throw a few scoops of snow on it and in the morning I have a good amount of charcoal. Some from the tin and some from the remaining fire.

[bsiler]

Thanks again jayco
I started to get some 1/4 inch wire.
I like the idea of the expanded metal scoop. I think I have some laying around here somewhere. Now just to find it.
The sparks do concern me. I try not to crank to hard and always try to keep a eye on the sparks. I thought about trying to fix a hood and chimney. Don't think it would help much. The shop is only about 10'x10'. A hood would take up room but it would help from burning the shop down it would be worth a try.
Thanks again for all the advice
Billy

You mentioned blueprints, a lot of the ones people here talk about I can find. The search part does not work for me.

[jayco]

It seems that hardwood charcoal produces less of the sparks, or 'fleas' than the softwoods ,like pine, produces.

As to the B P's.....several of them are currently off-line and are being 'reconfigured' for the site. They will return.

[Frosty]

A word of caution about charcoal. Store it outside of your shop in a sealed steel container, the chances it isn't out when you sift it out of the ashes is great.

Frosty

[bsiler]

A very good point Frosty. Thanks for the word of caution.
Billy

[jimbob]

bsiler, you mention fire danger from sparks in your log shop. yes, you do have to be careful of that........especially if you have horizontal beams/logs where sparks and hot scale can fly from the forge and start smoldering without you noticing.
I have some pieces of old roofing metal nailed to the wall behind my forge as a fire proof wall covering.

one of the other uses of borax if fire retardnt
...you might mix some up in a sprayer and coat the logs and let it soak in

[JohnW]

bsiler, I'd say you won't have any sparks when you forge if you stick with the 1/2" grid for sifting, and shake it real good. Don't breath the charcoal dust from sifting unless you want to avoid old age.

[olcarguy]

I use an air tight wood stove in my shop. When I go in for the night, I turn the dampers off so almost no air gets in. Come morning, I use a french fry basket and a shovel, sift over the ash bucket and save the charcoal thats in the basket...1/4 in holes..

[KELTOI]

What I do and it seems to work although ti is a bit time consuming...I use the fireplace tongs to remove the larger sized coals form the fire and quench them in a bucket of water. No so long that they get water logged, but long enough that they are no longer burning. Then I take the quenched charcoal and put it in a basket on top of the wood stove until it dries out completely!

[Scratch]

I also have an outdoor wood burner and use charcoal from it for my forge. Don't get a whole lot, but definitely enough to save!

[bsiler]

On the 2nd page of this thread jayco mentioned a sifting shovel made out of expanded metal. He said there was a blueprint for one of these. I'm just wondering if anyone has seen it. I figure I could make one but I had much rather see the blueprint first. Other people usually have better ideas than mine. I think this would work very good getting the hot cools from my furnace. Seems like there are a lot of blueprints I can't get.