Charcoal with stove pellets - TLUD

[mkn]

Hi All,

 

I was researching the TLUD method and came across the use of wood stove pellets.

 

Anyone tried to make coal with the Softwood woodstove pellets? Ours here in VT are from Canada and mostly spruce I believe.

 

If they work, it would be similar to making coal with sawdust, less grinding of larger pieces , the coal would break apart easily I would think.

 

I see people are using cedar chips and such so maybe this has legs?

 

A few different google searches of the forum did not return anything for me.

 

PS rolled another 3 lbs of coal stars yesterday.....

 

Thanks Matt

 

 

 

 

[Nessalco]

Matt,

 

Same idea crossed my mind, I just haven't yet had an opportunity to test it. I do know that I've cooked down SYP pellets that are about 1/4 the diameter of stove pellets, and they worked great. Good yield, slow cook. I'll grab a bag of pellets in a few days and give it a try.

 

Kevin

[pyrokid]

Can someone please explain the TLUD method to me like I'm stupid?

 

My understanding is that they pyrolize the wood, giving off flammable gas and leaving charcoal. Pyrolysis requires heat, right? Where does this come from? Isn't it desirable to minimize combustion inside the chamber? Is it a matter of finding the right balance between pyrolysis and oxidation?

[Bobosan]

Can someone please explain the TLUD method to me like I'm stupid?

 

My understanding is that they pyrolize the wood, giving off flammable gas and leaving charcoal. Pyrolysis requires heat, right? Where does this come from? Isn't it desirable to minimize combustion inside the chamber? Is it a matter of finding the right balance between pyrolysis and oxidation?

 

Correct. The heat is created from the tars and gases given off during pyrolysis. The TLUD pyrolysis cycle is initiated by an external means and sometimes an accelerant is used. It is not a closed system as there is oxygen admitted into the TLUD to sustain the pyrolysis. More reading and a better explanation can be found here.

 

With small pieces and shavings, it burns very fast but does not overcook the wood. Larger chunks get over cooked due to higher heat generated. At least that's been my experience with a one gallon TLUD.

 

TLUD cooker with pine shavings.

.

Edited August 5, 2014 by Bobosan

[mkn]

Matt,

 

Same idea crossed my mind, I just haven't yet had an opportunity to test it. I do know that I've cooked down SYP pellets that are about 1/4 the diameter of stove pellets, and they worked great. Good yield, slow cook. I'll grab a bag of pellets in a few days and give it a try.

 

Kevin

Look forward to the results as I would still need to build a TLUD, retort now for me with a Dutch oven ( melted my SS pot on my second run of coal)

 

 

Correct. The heat is created from the tars and gases given off during pyrolysis. The TLUD pyrolysis cycle is initiated by an external means and sometimes an accelerant is used. It is not a closed system as there is oxygen admitted into the TLUD to sustain the pyrolysis. More reading and a better explanation can be found here.

 

With small pieces and shavings, it burns very fast but does not overcook the wood. Larger chunks get over cooked due to higher heat generated. At least that's been my experience with a one gallon TLUD.

 

TLUD cooker with pine shavings.

.

Hi Bobosan,

 

Like your set up a lot, if I could ask a few questions:

 

is that 1/2 " holes in bottom of paint can?

how far from the bottom is the screen, looks like 1.5" +/-

in the side of your 6" to 4" reducer looks like 1" holes? how many?

 

Looks like you have the air / flow mix dialed in for the shavings !

 

That was real time for a bucket of shavings - sweet !

 

would a windy / breezy day affect the performance if the TLUD is in an unprotected area ?

 

Thanks Matt

 

Hummm, I 'm just getting started and I am already looking for easier ways to make coal.........

[Bobosan]

Matt,

 

All the holes are 5/8" top and bottom. 5 holes in can, 10 in the reducer. Figured more holes on top and less at bottom would allow a greater updraft and that seems to be working great for shavings. Loading the shavings into the can and cool down time was not recorded. Normally, 3 cans are used in rotation so there is one freshly loaded, one cooling and one cooking. I didn't have any undrilled lids so the lid with hole in it is normally used for my traditional retort cooking of bigger pieces.

 

The screen is hardware cloth placed on bottom of can. Be very careful using this as the cut ends will break down and leave bits of metal in the shavings when you dump them. You could use stainless screen or no screen at all but you'll loose some out the bottom. As a general rule, I always run a magnet through home made charcoal.

 

The only reason there is a 2 foot stack is because I was too lazy to cut it down. Wind is a factor when it blows the whole thing over because of the 2 foot stack sail. Other than that, wind doesn't affect the cook. It may cause some smoke to puff out the holes on top on occasion. Overall, a really clean burning process.

Edited August 6, 2014 by Bobosan

[pyrokid]

Could it be said then that the TLUD process is less efficient than retort cooking in terms of recovered charcoal mass? Is there a greater percentage of ash or other undesirables in TLUD charcoal?

 

Unless the gasified volatiles are being used to sustain pyrolysis, it seems that the only heat could come from combustion of material inside the vessel, which is contrary to our objectives.

 

Am I missing something?

Edited August 6, 2014 by pyrokid

[Nessalco]

Could it be said then that the TLUD process is less efficient than retort cooking in terms of recovered charcoal mass? Is there a greater percentage of ash or other undesirables in TLUD charcoal?

 

Unless the gasified volatiles are being used to sustain pyrolysis, it seems that the only heat could come from combustion of material inside the vessel, which is contrary to our objectives.

 

Am I missing something?

PK,

 

I've never cooked charcoal in a retort, so I'm not sure of the return. For most products cooked in a TLUD the return is between 18% and 23% of the original mass.

 

The pyrolysis occurs at a different level in the cooker than the combustion, which keeps the temperatures down to something pretty reasonable. I've cooked shavings, pellets, and splits, and they've all come out just fine. When cooking splits, the have an iridescent sheen and clink together like pieces of glass...

 

Only problem can be putting them out. If you don't effectively seal both inlet and outlet the burn continues, and you will end up with a pile of ash.

 

Kevin

[Bobosan]

In my experience using both methods, the return from what I call a "traditional" retort is much greater than TLUD. Shrinkage is roughly 10-15% and the sticks closely retain original shape. Same size sticks in a TLUD will result in a can of broken down charcoal. I have attributed this to more heat generated to cook the larger sticks does so slightly beyond the pyrolysis stage.

 

Another persons TLUD cooker may produce better results with entire large sticks. In the picture you can see the results of cooking large sticks in my TLUD (lower) vs. large sticks in traditional retort (top).

 

 

[Nessalco]

Splits I cook in a TLUD comes out like the stuff in the top of your picture, Bobosan. I think there is a tendency with some folks to try to accelerate the cook too much, with too much primary and not enough secondary air, and the cook temperature rises more than is necessary.

 

With a TLUD 90% of the inlet air should enter *above* the fuel mass. I've attached a pic of my cooker, made from a 20qt stainless steel stockpot. Notice the opening below the chimney, and the holes in the chimney. The lower opening spans the entire circumference of the cooker.

 

 

Kevin

[Bobosan]

Splits I cook in a TLUD comes out like the stuff in the top of your picture, Bobosan. I think there is a tendency with some folks to try to accelerate the cook too much, with too much primary and not enough secondary air, and the cook temperature rises more than is necessary.

 

With a TLUD 90% of the inlet air should enter *above* the fuel mass. I've attached a pic of my cooker, made from a 20qt stainless steel stockpot. Notice the opening below the chimney, and the holes in the chimney. The lower opening spans the entire circumference of the cooker.

 

Cooker2.JPG

 

Kevin

 

Makes sense when I see the results of large splits in my current cooker. Based on your info Kevin, if I closed off 4 of the 5 holes in the one gallon can and leave the 10 openings in the reducer, it should be close to that 90% ratio you mentioned and give me a slower but not hotter burn? I'll have to experiment with something other than the Paulownia.

[mkn]

Well I have my paint can TLUD with pine chips working great, I have two different bottom hole patterns, can say yet whether one is better or not. all I have is the 6 x 4 reducer( 10 - 1" holes around parameter) . with a 4" tomato can resting on top of that. No screen in the bottom, just load the shavings.

 

Kevin, what does the pattern on the bottom of your stock pot look like? I think I'm up grading to that size very soon.

 

 

TLUD - so far I like that I don't have to set up a propane cooker or other external heat source. Looking forward to trying splints ( I think you are talking about small sticks?) I have not made BP yet with the coal, but it looks good, I am very optimistic. I have cranked out 15 - 20 paint cans in a few hours. about 2-3 " of crushed coal in the bottom of a 5 gallon pail, a decent amount for stars, and a lot for BP

 

Nice burn, little if any smoke, no smell, I think it will be fun in the winter when I need a small fire to hang by, or beat the winter doldrums,

 

Matt

[Nessalco]

The bottom of my cook pots have twenty-four 1/4" holes, randomly distributed. A load of cedar shaving takes ~12-13 minutes, a load of SYP pellets takes a little over an hour.

 

Splits are indeed small sticks. I have cooked a number of different woods in the TLUD, in different forms, and they all cook generally well. The key thing is to get uniform size pieces. Woods that split easily, like aspen, you simply hack up the wood into sticks. You can also make shavings if you have a jointer, or use whole stem pieces up to about 1" diameter for woods like sumac.

 

I have successfully cooked red oak, aspen, apple, yellow pine, red cedar, buckthorn, grape vine, sumac, cattail stalks, and pin (fire) cherry. The pellet, split, or chunk form woods give the best yields.

 

BTW - if you happen to cook sumac in one of these, wear a respirator. The smoke, while not toxic, is very irritating.

 

Kevin

[Nessalco]

 

Makes sense when I see the results of large splits in my current cooker. Based on your info Kevin, if I closed off 4 of the 5 holes in the one gallon can and leave the 10 openings in the reducer, it should be close to that 90% ratio you mentioned and give me a slower but not hotter burn? I'll have to experiment with something other than the Paulownia.

 

The distribution of the holes is important-ish. They need to admit air across as wide an area of the bottom as possible. If you only have 1 hole, you'll need some sort of screen to help distribute air across the bottom of the mass.

 

I checked the numbers you mentioned. For a 1 gallon paint can, you had an inlet area of ~ 3 square inches. That would lead to a very hot cook. For a 20 quart cooker (5x as large) I have an inlet area of 1.17 square inch. Even if you cut down to one 5/8" hole, you will be running with a 25% greater inlet area per quart of volume than I do.

 

Paint cans are cheap. Punch some smaller holes and give it a try!!

 

Kevin

[Arthur]

The issue with "stove pellets" is simply that the wood is unspecified. In pyro we get fussy what wood we use for different purposes. Read a few posts about Willow, Alder, Pawlonia and Pine. Half the pyro products and effects are caused by the correct choice of starting materials, picking a random (mix) of woods is hardly a great start.

[dagabu]

Not the stuff from tractor Supply, its all SYP.

 

http://www.tractorsupply.com/en/store/tractor-supply-coreg%3B-pine-pellet-stall-bedding-40-lb

[MrB]

Not the stuff from tractor Supply, its all SYP.

 

http://www.tractorsupply.com/en/store/tractor-supply-coreg%3B-pine-pellet-stall-bedding-40-lb

There is a potential advantage to using this stuff as charcoal as well... It's actually already dust. Shouldn't take to much to make it back in to dust after cooking.

 

That said, i'm pretty sure pellets for stove burning has specified what kind / kinds of woods are used. I'll see if i cant swing by the stove retailer my uncle just happens to be a silent partner in, and see if i cant get a peek at the details.

B!

[mkn]

Hi All,

 

This weekend I made some coal from the spruce wood stove pellets with TLUD Paint can. " Spruce Point " brand from Canada.

 

My can full burned for 1 Hr. 40 mins. reliably over many cans. Each can gave 1# of coal.

 

The tiny pellet sized coal would give a tiny " clink " as described before.

 

The TLUD burned completely each time, no unburned for me to remove.

 

 

They were easy to work with, if you want to crush them they fall apart with finger pressure. I liked that in the pellet form they did not consume too much volume in my mill as Pine coal can do causing it to be too full.

I use the small rubber mill from Thumblers, with the 5 # of lead, I load 254g of mix and mill for 3 hrs.

 

 

Now to the BP test, I do BPCRH at 3:1 ratio. I ran the base ball test I used 10% of the ball weight, 14.4 g and accounted for the rice hulls at x 1.25 = 18g

 

Total flight time was 7 seconds, according to Ned's info on Skylighter, that is a 300' flight.

 

All in all not highly reactive powder, but very solid for service and the coal could not be easier. and cheap at $ 5/ $6 for a 40# bag of pellets.

 

I will be burning a lot of this coal !

 

Matt

[Bobosan]

Matt,

 

Does the pellet bag specify content? ie. % of wood or % of binder.

[mkn]

They say " 100 % natural , no additives, no bark, and .5% ash "

 

I did not think any binder was used in pellets, just the heat and force to pelletize them held them together.

[taiwanluthiers]

I think from a documentary they explained how fuel pellets are made...

 

Basically they heat the wood dust to a temperature where the natural wood binders within the wood dust melts, and then they press it into a pellet with a press.

Edited October 13, 2014 by taiwanluthiers

[dagabu]

There is a LOT of speculation about binders and such with pellets, most of that is generated by individuals that look at the machines for home use that pamke pellets. The binders there make dustless pellets and they leave no residue. I agree that the commercial pellets rely on the natural resins to bind the pellets.

[Bobosan]

Based on the percentages that mkn has listed from the bag, I would agree. Sounds like a quick easy way for charcoal.

[dagabu]

Based on the percentages that mkn has listed from the bag, I would agree. Sounds like a quick easy way for charcoal.

 

In a TLUD, it is not only easy but virtually smoke free to boot!

[Bobosan]

 

In a TLUD, it is not only easy but virtually smoke free to boot!

+1 yup!