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Dan O'Connor

Making Charcoal

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Dan,

Congratulation on the pinning. Do you have any numbers regarding yield and "effort" in terms of hours spent per lbs of charcoal?

 

 

Just today I was in the hood begging for the tree trimmed discards of neighbors ( saving them from the chipper and directing it to the Branch Manager). I will be sticking with the pit method, as it is relatively fast, and I have become addicted to the light fluffy charcoal. I hope to do several runs at about 160 lbs per run yield. I will attempt to keep track of my time and expenses to give readers an idea of what may be involved ( we know it is homemade, not "free" ). There is a Pizza oven on the horizon..I have the form and just need some time.

 

Jan

 

Jan,

Yield is about 40 lbs per barrel in 6-8 hours.

 

 

 

One of my criteria is that it can be done in a reasonable time. Whatever my final system is it will be a good days work 8 hours or so. A system like the barrel can have multiple instances running to get larger quantities.

 

You are right about costs. In my case I have to hook up my trailer, drive 30- 40 minutes to a construction site, gather scrap wood, drive back and unload.

Then cut the wood if it is to long, load the barrel, conduct the burn, unload into bags. Then later chop the charcoal.

 

Time wise it is an expensive fuel. However there is something addictive about the process of making and the use of charcoal. Not everything can be boiled down to a cost/benefit ratio.

I have dealt with that enough in my manufacturing and sales careers.

I have no idea nor do I want to know how much time every pound of charcoal costs me. :D

 

How long does a pit burn take?

I wouldn't mind learning more about your pit burning method.

 

Dan

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Jan,

Yield is about 40 lbs per barrel in 6-8 hours.

 

 

 

One of my criteria is that it can be done in a reasonable time. Whatever my final system is it will be a good days work 8 hours or so. A system like the barrel can have multiple instances running to get larger quantities.

 

You are right about costs. In my case I have to hook up my trailer, drive 30- 40 minutes to a construction site, gather scrap wood, drive back and unload.

Then cut the wood if it is to long, load the barrel, conduct the burn, unload into bags. Then later chop the charcoal.

 

Time wise it is an expensive fuel. However there is something addictive about the process of making and the use of charcoal. Not everything can be boiled down to a cost/benefit ratio.

I have dealt with that enough in my manufacturing and sales careers.

I have no idea nor do I want to know how much time every pound of charcoal costs me. :D

 

How long does a pit burn take?

I wouldn't mind learning more about your pit burning method.

 

Dan

 

Dan,

I forgot about the accountant ( which most of us have and probably need). A pit burn is basically a camp fire, where the coals are saved...I cover the smoldering charcoal with a steel plate after the flames begin to subside ( about 2 hrs of burning...the fire is fed as fast as it will take the wood without creating a lot of smoke). I am looking for some used clay bricks to line the pit as some stones decompose at the temperature. The pit shown in the photos does not exist and will have to be dug again. Fast feeding the fire is really important or you will just have a continuous burn and lose too much wood. The wood stash I am targeting is mostly pine/fir and a little hard wood. I will post some pictures when our burn season starts.

 

 

 

 

 

Jan

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I stumbled across your thread a few days ago in my searching for practical information on making charcoal for use in forge work. I have found and read hundreds of pages of information on this in the last few days, but I have to say this thread is the most informative I have found on the subject. In fact this thread is the initial reason I joined this site.

 

I have always been a bit of a science nerd, when other guys were takeing woodworking I was taking astro physics. I have been aware of destructive evaporation since I was around 12yrs old 30 years ago. My interests along this line have always been more for the gas fuel that results than for the carbon production that results. I have dreamed since childhood about pouring and working metal, there is just something magical about the whole idea, I was lucky enough to work in a small foundry in Portland for a while when I was 17 pouring bells and figurines, fascinating as all get out. Now that my youngest children are in school I have a lot more time in the day to work (play) so I decided to follow my dream of learning to forge. My chosen fuel is a no brainer, I have 50 acres of timber and also am partners in a small mill as well, and a best friend that has a tree trimming company and a horse logging company and my nieghbor also owns a logging company, as well as three other friends that run private mills for buisness. I quite litterally have wood coming out of my ears.

 

Before I build my pyrolysis tank I wanted to try and find some exact specifics on peoples experience at making it and that is when I found this thread. This is by far the most usefull info I have found on this subject.

 

I have a number of 250 gallon fuel tanks one that I have already used to make a giant outdoor fireplace as a backup heat source for the house and for burning up garbage and brush. With one of the others I wanted to make a pyrolysis tank to create my fuel to forge with.

 

My tanks are 60 inches long, 44 inches deep and 27 inches wide, they are fairly heavy duty and after two years of running the outdoor fireplace hold up well to very hot fires. These tanks have 27.7 cubic feet of space within them which will hold a good deal of wood, I will be cutting logs to 56 inches and standing them up in there packed as tightly as possible, it should be around 600 to 800 pounds of wood per burn in the tank.

 

One of my concerns is about the potential of gas pressure build up, with something of this size, the idea of explosive gasses rupturing the tank and detonating spooks me more than a bit.

 

From looking at your fancy 55 gallon drum setup it looks as though you are using 2 inch pipe to outflow the gasses, do you think two inch pipe would hold up on something this size without building up back pressure? I have three 2 inch threaded holes on one side of each tank that I can plumb from, should I consider a larger diameter of pipe to reduce back pressure?

 

I would like to stand the tank on end so that it is five foot tall and place it atop a burn chamber and run the outgasses under it to the burn chamber. I was thinking of bolting a piece of 1/2 inch plate under the tank to protect the metal from the fire. The exhaust gasses from the flame would then be routed through a piece od culvert about 20 inches in diameter that will be surrounde by a 44 inch steel tank and filled with clay. I was hoping to eventually use this setup as a foundry, fill the bottom of the culvert with three feet of charcoal or so and turn on the blower while running the carbonisation tank for added heat.

 

My biggest concern here is making sure I do not blow myself up, my little brother nick named me "Maximum Overkill" a long time ago, and I have too admit I do go a little overboard, which has led to some past misshaps that luckily were not fatal to me or anyone else.

 

I would love to hear any safety concerns about this setup and any ideas on making sure this could be done safely. Looking forward to hearing from you all.

Edited by Roy Edward

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I would love to hear any safety concerns about this setup and any ideas on making sure this could be done safely. Looking forward to hearing from you all.

 

Roy,

 

Three 2" outlet pipes should be fine. As long as the lid is clamped on well I don't believe you will have any pressure issues.

 

How hard and fast you heat the wood has a lot to do with how hard and fast the gas comes out. Build a big fire and gas will come out quickly and fast maintaining a big fire.

 

Heat gently and the gases will come out at lower speed and pressure.

 

Keep in mind that the quality of the charcoal is mostly dependent on the temperature of pyrolysis and to time of cooking. I would recommend a temperature probe to monitor the temperature. You are going to need about 750F-850F for the gases to be hot enough to ignite. This also seems to be a pretty good temperature to cook the wood. Keeping it close will give you some nice charcoal. Letting it run away to very high temps quickly will explode your charcoal and make it crumbly and weak.

 

Make sure you can close every air inlet and outlet tightly to kill the burn. Otherwise you will simply be burning up your charcoal when it is supposed to be cooling down.

 

There is not as much pressure as you might think. If you notice at the beginning of this thread my little test can was just a paint can with lid pressed on as usual. Obviously if there is no way for the gas to escape then you have a problem, but as long as there is a vent you are OK.

Edited by Danocon

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Roy,

 

Three 2" outlet pipes should be fine. As long as the lid is clamped on well I don't believe you will have any pressure issues.

 

How hard and fast you heat the wood has a lot to do with how hard and fast the gas comes out. Build a big fire and gas will come out quickly and fast maintaining a big fire.

 

Heat gently and the gases will come out at lower speed and pressure.

 

Keep in mind that the quality of the charcoal is mostly dependent on the temperature of pyrolysis and to time of cooking. I would recommend a temperature probe to monitor the temperature. You are going to need about 750F-850F for the gases to be hot enough to ignite. This also seems to be a pretty good temperature to cook the wood. Keeping it close will give you some nice charcoal. Letting it run away to very high temps quickly will explode your charcoal and make it crumbly and weak.

 

Make sure you can close every air inlet and outlet tightly to kill the burn. Otherwise you will simply be burning up your charcoal when it is supposed to be cooling down.

 

There is not as much pressure as you might think. If you notice at the beginning of this thread my little test can was just a paint can with lid pressed on as usual. Obviously if there is no way for the gas to escape then you have a problem, but as long as there is a vent you are OK.

 

 

Reading that makes me feel a bit better, I did some calculations and I came up with around 15,000 cubic feet of gas flow as long as it is relatively dry wood. The calculations for green wood run over 20,000 cu feet of steam and a max of about 5,000 cubic feet of volatiles from the 850 pound wood load. In a five hour burn this would pass 5,000 cubic feet of gass an hour.

 

I can reduce outgass volume the most by using dry wood, the only real question left is how do I control the speed of reaction. If I plumb the outgass to the firebox I lose control of the heat process, it is then determined by it's own mechanics.

 

I was considering the potential of running a valve that would allow me to divert outgass to the atmosphere to reduce the fire heat under the tank. I am hopeing this would give me a reasonable amount of control over the speed of the process. From what I have read you are dead on with the cooking temp, there is no doubt it will take some experimentation and trial and error to be able to control it to the right temp. My biggest worry was the idea of a runawy process producing back pressure and rupturing the tank, in my mind that could equal big boom.... These tanks should be able to hold 15 to 20 psi without rupturing, though flexing in and out a lot will fracture the metal after a while.

 

Having had some experience with kiln drying log home logs, I realised that our curfing the logs before kilning them to aid in drying may also work well on charcoal production. The gasses inside the wood have a hard time escaping in a full log, but if you cut a curf to the heart wood you allow an escape route for the gasses. This may not be of any use to you with the type of wood you are using, but it may help to reduce shattering when using logs.

 

One question, how long does it take for your tanks to cool down enough for removal?... Granted my tanks are quite a bit bigger and much more mass to cool off but still gives me a bit of a guess.

 

Another potential idea, for those who cannot completely seal off the possibility of air leaking in on cool down, could they fill all dead space with sawdust, giving less air cavity and excess useless carbon to waste on the leaking O2. I am guestimating that I will have around 5 to 6 cubic feet of dead air space in each burn no matter how tight I try to pack it, the thought of filling that with sawdust entered my head, beings I can get it by the truckload for free 6 miles from my house. Is there any sense to this, or is it just wasted effort and causing a dirty mess to deal with.

 

Thanks for taking the time to respond to my post, I have learned from experience that I am just intelligent enough to be dangerous... As I get older I am a little less willing to just cross my fingers and go.

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Reading that makes me feel a bit better, I did some calculations and I came up with around 15,000 cubic feet of gas flow as long as it is relatively dry wood. The calculations for green wood run over 20,000 cu feet of steam and a max of about 5,000 cubic feet of volatiles from the 850 pound wood load. In a five hour burn this would pass 5,000 cubic feet of gass an hour.

 

I can reduce outgass volume the most by using dry wood, the only real question left is how do I control the speed of reaction. If I plumb the outgass to the firebox I lose control of the heat process, it is then determined by it's own mechanics.

 

I was considering the potential of running a valve that would allow me to divert outgass to the atmosphere to reduce the fire heat under the tank. I am hopeing this would give me a reasonable amount of control over the speed of the process. From what I have read you are dead on with the cooking temp, there is no doubt it will take some experimentation and trial and error to be able to control it to the right temp. My biggest worry was the idea of a runawy process producing back pressure and rupturing the tank, in my mind that could equal big boom.... These tanks should be able to hold 15 to 20 psi without rupturing, though flexing in and out a lot will fracture the metal after a while.

 

Having had some experience with kiln drying log home logs, I realised that our curfing the logs before kilning them to aid in drying may also work well on charcoal production. The gasses inside the wood have a hard time escaping in a full log, but if you cut a curf to the heart wood you allow an escape route for the gasses. This may not be of any use to you with the type of wood you are using, but it may help to reduce shattering when using logs.

 

One question, how long does it take for your tanks to cool down enough for removal?... Granted my tanks are quite a bit bigger and much more mass to cool off but still gives me a bit of a guess.

 

Another potential idea, for those who cannot completely seal off the possibility of air leaking in on cool down, could they fill all dead space with sawdust, giving less air cavity and excess useless carbon to waste on the leaking O2. I am guestimating that I will have around 5 to 6 cubic feet of dead air space in each burn no matter how tight I try to pack it, the thought of filling that with sawdust entered my head, beings I can get it by the truckload for free 6 miles from my house. Is there any sense to this, or is it just wasted effort and causing a dirty mess to deal with.

 

Thanks for taking the time to respond to my post, I have learned from experience that I am just intelligent enough to be dangerous... As I get older I am a little less willing to just cross my fingers and go.

 

Roy,

The dead airspace is not an issue. The wood will shrink in volume and there will be empty space. Think more in terms of oxygen. As you heat the wood all the gases (oxygen included) are forced out of the system by heat and pressure. Only when the pressure stops flowing out can oxygen come back in with air flow. That is when you need to close off all air acess points. In fact kill the burn before all the gasses have quit flaming. Will take experience to know when the right moment has arrived.

 

Your idea of venting gasses to the atmosphere I think is a good one. At the moment I have gone completely away from the retort method but if I was still doing that is what I would try first. The reaction produces much more energy than it needs to sustain itself. There is a LOT of room here for experimentation utilizing the energy released.

 

Determine what you want your end product to be

 

Biochar-Heat that baby up to the max as fast as you can and burn it till it stops. Soft crumbly charcoal that is mostly carbon and little retained volatiles.

 

Cooking charcoal- Heat a a lower temp (750-900F) but cook off the volatiles (tar and methane taste bad.)Nice solid charcoal that heats evenly.

 

Forging charcoal. 750-800F Max keep some of the volatiles. Looking for about 80% carbon 20% volatiles. You can measure the volatile content by carefully weighing a sample. Cooking until there is no gas escaping and weigh again.

 

Best test though is to burn it in a forge and see what you get. Nice hot glow with no flame with air blast-little or no volatility. bright Yellow glow with good flame when air blast hits it more volatiles. Best is yellow with some blue flame to it near the coals. Not very precise but it works.

 

You might want to think about a smaller set up to experiment with. It won't transfer directly because every set up has its own parameters but it may keep you from burning great big honking loads of wood needlessly.

 

Split wood is best. I don't know if cutting a kerf will make a big difference. Surprisingly length of wood has more effect on time the thickness. Seems that wood pyrolyze from the ends.

 

When you start your burn the temperature will reach the boiling point of water and stay there until all the moisture is driven off then will rise quickly. So don't pour the heat to it thinking nothing is happening. You are just wasting fuel

 

I don't know exactly how long it takes my barrels to cool down. If I do a burn in the afternoon I know that it is cool enough to open the next morning.

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Roy,

The dead airspace is not an issue. The wood will shrink in volume and there will be empty space. Think more in terms of oxygen. As you heat the wood all the gases (oxygen included) are forced out of the system by heat and pressure. Only when the pressure stops flowing out can oxygen come back in with air flow. That is when you need to close off all air acess points. In fact kill the burn before all the gasses have quit flaming. Will take experience to know when the right moment has arrived.

 

Your idea of venting gasses to the atmosphere I think is a good one. At the moment I have gone completely away from the retort method but if I was still doing that is what I would try first. The reaction produces much more energy than it needs to sustain itself. There is a LOT of room here for experimentation utilizing the energy released.

 

Determine what you want your end product to be

 

Biochar-Heat that baby up to the max as fast as you can and burn it till it stops. Soft crumbly charcoal that is mostly carbon and little retained volatiles.

 

Cooking charcoal- Heat a a lower temp (750-900F) but cook off the volatiles (tar and methane taste bad.)Nice solid charcoal that heats evenly.

 

Forging charcoal. 750-800F Max keep some of the volatiles. Looking for about 80% carbon 20% volatiles. You can measure the volatile content by carefully weighing a sample. Cooking until there is no gas escaping and weigh again.

 

Best test though is to burn it in a forge and see what you get. Nice hot glow with no flame with air blast-little or no volatility. bright Yellow glow with good flame when air blast hits it more volatiles. Best is yellow with some blue flame to it near the coals. Not very precise but it works.

 

You might want to think about a smaller set up to experiment with. It won't transfer directly because every set up has its own parameters but it may keep you from burning great big honking loads of wood needlessly.

 

Split wood is best. I don't know if cutting a kerf will make a big difference. Surprisingly length of wood has more effect on time the thickness. Seems that wood pyrolyze from the ends.

 

When you start your burn the temperature will reach the boiling point of water and stay there until all the moisture is driven off then will rise quickly. So don't pour the heat to it thinking nothing is happening. You are just wasting fuel

 

I don't know exactly how long it takes my barrels to cool down. If I do a burn in the afternoon I know that it is cool enough to open the next morning.

 

 

Man this is handy information, I gave the venting outflow gasses a lot of thought last night and this morning, and was concerned about what all valves would hold up to high temps, I do have some but the idea of buying any in a two inch size would be spendy. I finally realised that I do not actually need valves at all, I can simply swing the pipes out from under the tank therbye removing one or all flame and heat sources. They will have a threaded 90 sending the pipe under so they will easily swing out from under if I desire.

 

If I watch the temp of the oustside of the tank and when it reaches 800 or so I remove one of the flames from heating, if the temp has not stabalised or dropped in a few minutes I can remove another flame to the outside. I can completely remove the heat source easily at any time with this method. I can also use a threaded 90 on the end of each pipe so that I can turn a plug into them to seal them off when the burn is done.

 

In the tank that I think I have decided to use, I have two 2 1/4 inch threaded holes and a 1 3/4 inch threaded hole, I think I will initially use the 1 and 3/4 and one of the others to run my outgasses on two different pipes under the tank. Now to figure out the exact specifics on my door and I should be ready to build by this weekend, I think. I have an old pine tree that broke off on the edge of one of my fields that I need to get up and that will supply me about 5-6 truckloads of wood for testing on. I also have a chinese pickup sticks mess at the edge of another field where 4 large pines and 5 midsized red firs came down all together in a domino chain.

 

I am not terribly worried about wasting a little wood, I still have about 40 truckloads of wood in slash piles and at least 200 trees down that need to be cleaned up. This does not include the 10 truckloads or so I am supposed to have already picked up at the mills, though I did manage to get two loads last week.

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I purchased a very informative document online called

 

The Art,Science,and Technology of Charcoal Production

Michael Jerry Antal, Jr.*

Hawaii Natural Energy Institute, University of Hawaii at Manoa, Honolulu, Hawaii 96822

Morten Grønli

SINTEF Energy Research, Thermal Energy, 7465 Trondheim, Norway

 

Made me feel a little better about my attempts to produce good charcoal using simple methods.

 

Filled in some gaps on why some things work and gave me new avenues to go down.

I don't mind trial and error but a road map is always nice.

 

They cited 206 different publications on Charcoal.

One of them

The Chinese Charcoal Kiln Chaturvedi,M.D. 1943

stated

Charcoal of good quality retains the grain of the wood;it is jet black in color with a shining luster in a fresh cross-section.It is sonorous with a metallic ring,and does not crush,nor does it soil the fingers.It floats in water,is a bad conductor of heat and electricity,and burns without flame.”

 

At the end of the paper the authors made this statement

"Despite our 38,000 years of experience with charcoal,its secrets continue to confound and captivate us".

 

Amen to that-Who would have thought that this mundane element in our lives would hold so many secrets. :D

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I purchased a very informative document online called

 

The Chinese Charcoal Kiln Chaturvedi,M.D. 1943

stated

Charcoal of good quality retains the grain of the wood;it is jet black in color with a shining luster in a fresh cross-section.It is sonorous with a metallic ring,and does not crush,nor does it soil the fingers.It floats in water,is a bad conductor of heat and electricity,and burns without flame.”

 

 

Dan,

I agree 100% with this definition of "good" charcoal.....the pit charcoal I make is soft crumbly and soils the fingers. My short furnace is quite short...do I really need to set such high charcoal specifications. There are some advantages to the pit method, low investment of materials, raw material is waste, takes a short time and Zero smoke generation. I have just gathered a bunch of pine branches and hope it does as well as the hardwood has done in the past.

 

Jan

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Heya Dan-

 

I've made a few improvement to my barrel method since I wrote that, so I figured I'd share. ...

 

The biggest thing was welding on 3/4 pipe nipples over the holes, so I can shut it down quickly and definitely with pipe caps, which saves lost coal. And instead of a hole in the lid, I just lay it partway on when I want to slow it down. The slower I go, the more and better coal I get- I'm running 5 or 6 hours, i think, and getting about 30 lbs of coal per barrel,after chopping and sifting. I've been running 4 holes open awhile (in an X pattern), and then switching to the other holes.

 

OK pictures wortha thousand words-

 

C1.jpg

 

C2.jpg

 

C3.jpg

 

C4.jpg

 

BTW, Michael McCarthy rigged a tight hood and stovepipe to his, kind like you did, and heats his shop while he's making coal (probably not an issue in Texas!)

 

Cheers-

 

Lee

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Hey Lee,

 

I ended up doing something similar by putting a metal swivel flap over the hole that I could open or close. Was marginally successful given the curvature of the barrel. But did give me more control than dirt.

 

I like you pipes. As you say you can seal them of completely.

 

One of the things that the paper went into great detail about is gas flow. As in how fast the gases leave the wood. The focus of this paper is making charcoal not the distillate by products. Basically they said that you can configure your system to maximize char yield or distillate yield. One will be at the expense of the other.

 

The idea is to get as much of the tarry vapors as they called them to carbonize with the wood. They had about a 4% (by weight)increase in yield just by restricting the outflow of the gases.

 

The Japanese figured this out long ago. The smoke exit hole is pretty small compared to the volume of the kiln. On a 12 foot diameter kiln with a height of 5 feet the exit hole is about 8 inches by 3 inches.

 

Pressure was a factor as well. At 75 PSI there was about 5% increase in yield. Not possible in an open kiln but doable in a stout retort.

 

From high flow-low pressure to low flow-high pressure they reported an increase in yield by about 9%

 

In these particular tests there was no mention of the quality of the charcoal. But it seems pretty apparent that heavier fully carbonized charcoal is better than lighter charcoal of the same wood species.

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Dan,

I forgot about the accountant ( which most of us have and probably need). A pit burn is basically a camp fire, where the coals are saved...I cover the smoldering charcoal with a steel plate after the flames begin to subside ( about 2 hrs of burning...the fire is fed as fast as it will take the wood without creating a lot of smoke). I am looking for some used clay bricks to line the pit as some stones decompose at the temperature. The pit shown in the photos does not exist and will have to be dug again. Fast feeding the fire is really important or you will just have a continuous burn and lose too much wood.

 

Jan

 

Dan,

I keep looking in the "bloomers" forum and not finding this post...I think I have it now. The pine/fir branches are gathered ( they are a little larger than ideal ) and some sheet metal to prevent the dirt walls from collapsing has been located. I will be digging a 4' X 4' by 3' deep hole and lining it with some discarded sheet metal shelves. I will try to stabilize the dirt prior to digging, hoping the collapse is minimal. The sheet metal ( gap between the dirt and metal) will be backed by old charcoal fines for insulation and dirt support. After a few runs I will recycle the sheet metal and refill the hole. I have only done this with mixed wood and do not know if the soft wood will work. I am trying to avoid the cost of all the bricks required to do it properly.

If I can fill that hole with charcoal I will have 48 cubic feet of material....... at 7.5 gallons per cubic feet and 1 lb per gallon of charcoal I will probably end up with 150 lbs of usable charcoal and lots of fines. I will take up the use of fines in another post.

As I proceed, I have to keep reminding myself that I am burning the volatiles in the wood, not the wood. I will post some pics. early in January.

 

 

 

 

 

Jan

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Dan,

I keep looking in the "bloomers" forum and not finding this post...I think I have it now. The pine/fir branches are gathered ( they are a little larger than ideal ) and some sheet metal to prevent the dirt walls from collapsing has been located. I will be digging a 4' X 4' by 3' deep hole and lining it with some discarded sheet metal shelves. I will try to stabilize the dirt prior to digging, hoping the collapse is minimal. The sheet metal ( gap between the dirt and metal) will be backed by old charcoal fines for insulation and dirt support. After a few runs I will recycle the sheet metal and refill the hole. I have only done this with mixed wood and do not know if the soft wood will work. I am trying to avoid the cost of all the bricks required to do it properly.

If I can fill that hole with charcoal I will have 48 cubic feet of material....... at 7.5 gallons per cubic feet and 1 lb per gallon of charcoal I will probably end up with 150 lbs of usable charcoal and lots of fines. I will take up the use of fines in another post.

As I proceed, I have to keep reminding myself that I am burning the volatiles in the wood, not the wood. I will post some pics. early in January.

 

 

 

 

 

Jan

 

Jan,

 

Pine burns very easily. Once the burn is established (and that happens quickly as well). It takes very little air to carbonize it. An 8 foot diameter Japanese kiln only needs an opening of 2 square inches or less to burn. If you have a charcoal grill thermometer handy try to keep the temp at 600-700F.

 

Good luck

 

Dan

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Jan,

 

Pine burns very easily. Once the burn is established (and that happens quickly as well). It takes very little air to carbonize it. An 8 foot diameter Japanese kiln only needs an opening of 2 square inches or less to burn. If you have a charcoal grill thermometer handy try to keep the temp at 600-700F.

 

Good luck

 

Dan

 

Dan,

This is a wide open pit, I stay as far away as possible , no control. The process is quite similar to the one lee shows using the two barrels...I sometimes struggle to stop the process even after covering the pit. A good wood stove ( lined with lots of refractory in the combustion zone) will make charcoal out of 2-3" wood in about 20 minutes.

 

Jan

Edited by Jan Ysselstein

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I have a one interest:

I read a book on old Czech knife makers, and there was written that them burned charcoal in the oven for baking bread.

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I have a one interest:

I read a book on old Czech knife makers, and there was written that them burned charcoal in the oven for baking bread.

 

Hloh,

 

I can see that working.

The way a wood-fired bread oven works is that the oven is filled with wood and fired for 4-5 hours-maybe more. The huge thermal mass of the oven (bricks, clay even concrete)absorbs the heat and retains it. The remaining coals are raked out and the ashes brushed away. A fine mist of water is sprayed in the oven for humidity and then the baker loads the loaves of dough he has prepared while the oven had been firing.The bread is baked by the retained heat of the oven. Depending on the size of the oven and the amount of thermal mass it has as many as 15-20 loads of bread can be baked through out the day. There is no high tech alternative to achieve the same taste and texture.

 

If the wood was managed to get charcoal before it completely burned up then I could see a goodly amount of charcoal being produced since the ovens are fired every day.

 

There has been a big resurgence in naturally leavened (sourdough) wood-fired breads and there are numerous books on the subject as well as many international bread baking competitions. There may be bakers in your area you could approach.

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I want to build an earth oven, so that possibility makes my happy. But how cool burning charcoal? Put it into water?

Here I found some video from making fire in earth oven there is to see that wood carbonize:

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I always thought that there where only two types of charcoal making-Direct where a fire is built within the wood to be coaled and indirect where the wood is cooked in a sealed container (retort). There is third way where the wood is carbonized by the hot gases from a fire. Kind of an indirect/direct system. This the method the Japanese use.

After spending way too much time on the internet. A search for Japanese charcoal kiln returns 430,000 records. I looked thorough around a thousand of them. I feel I have a beginning handle in the kiln design and technique. So, after many small scale tests I have built a mid size kiln.

 

Dirt is your friend here. It seals and insulates.

 

Here is the enclosure I built from landscape timbers.

 

kiln5.jpg

 

Kiln with coaling chamber and fire box. Yuki always manages to get in the picture at some point.

 

kiln6.jpg

 

Filling in the dirt

kiln4.jpg

 

Almost full

kiln3.jpg

 

Dirt in place with top on. Dirt will piled on top as well once wood is loaded.

kiln2.jpg

 

Front view

Kiln1.jpg

 

I still have some liquid collection and gas burnoff work to do.

 

I have found a sawmill where I can get southern yellow pine drops for charcoaling. I will try this rather than the kiln dried 2x4s.

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I always thought that there where only two types of charcoal making-Direct where a fire is built within the wood to be coaled and indirect where the wood is cooked in a sealed container (retort). There is third way where the wood is carbonized by the hot gases from a fire. Kind of an indirect/direct system. This the method the Japanese use.

After spending way too much time on the internet. A search for Japanese charcoal kiln returns 430,000 records. I looked thorough around a thousand of them. I feel I have a beginning handle in the kiln design and technique. So, after many small scale tests I have built a mid size kiln.

 

I still have some liquid collection and gas burnoff work to do.

I have found a sawmill where I can get southern yellow pine drops for charcoaling. I will try this rather than the kiln dried 2x4s.

 

Dan,

This looks interesting and should give a pretty good volume...good luck on the project.

 

Jan

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Very interesting. Is there a gate between the horizontal barrel and the chamber? How did you figure the sizing of the chambers and height of chimney?

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Very interesting. Is there a gate between the horizontal barrel and the chamber? How did you figure the sizing of the chambers and height of chimney?

Jesus,

 

There is a small opening between the chambers.

kiln7.jpg

The idea it keep the flame away from the wood to be coaled and only send heat and flue gas with no oxygen into the chamber.

 

The size of the chambers is a guess. The chimney will be routed into a liquid recovery system and the residual gas will be burned away-I hope.

 

Right now I am not worrying much about using the residual gas for firing the combustion chamber. I am going to stick with traditional methods until I get a handle on it.

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Pile of scrap yellow pine blocks at an East Texas sawmill.

I tried some white pine log ends last month in my test kiln from a company that brings them in for

log homes from Montana. Wasn't very impressed with it.

 

maxwell2.jpg

 

Loaded and ready to go.

maxwell1.jpg

 

Didn't get a full load. Wasn't sure how well my little Jeep Diesel would pull it.

Had no problems. I will fill it up next time.

$20 a load. Cut square and virtually no bark.

 

Loaded up some oak as well for the fire in the combustion chamber.

On the down hill side now maybe one more week to make the first burn.

 

 

Pine logs waiting to be milled

maxwell3.jpg

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Wow! Awesome Dan.

Do you plan to split these, or go with them as is?

 

Great looking cooker. I hope it works like a charm for you.

 

Mark

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Wow! Awesome Dan.

Do you plan to split these, or go with them as is?

 

Great looking cooker. I hope it works like a charm for you.

 

Mark

 

Thanks Mark,

 

I will split at least once.

One more task to add to the process. <_<

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