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Charcoal Retort

September 28, 2010

This is my latest project.

I was at a friends house this past weekend and he had 3 White ash trees that were cut down about 7 months ago, anyhow I stopped over to help him split the wood, in return I was going to use some of the wood for my Smoker.


     


As we cut the wood, we came across some Longhorn Beetles, Wasp Beetles to be exact, anyhow we started splitting and about 2+ cords later, we
were tired  and beetles were everywhere, there wasn't a piece of that poor ash they didn't infest.

So now he has 2+ cords of wood that can not be moved and he needs to utilize it somehow, So I did a bit of research and hopefully we can turn some of that useless wood into good quality lump charcoal that we can use on our smokers, that's right, were gonna carbonize those critters.





How this is supposed to work, I hope I worded this correctly.
 
  • Fill a 55 gallon drum with Bio Mass (wood or other materials, Pine works also),
  • Secure the Lid  on the drum
  • Build a fire underneath the barrel. Water vapor will burn off first, approximately 2 hours into the burn drying out the wood. Now before it becomes charcoal, two chemical reactions will take place, pyrolysis and gasification, pyrolysis is the decomposition of the bio mass resulting in gassification igniting the pipe underneath the barrel.
  • When the gasification process has begun, stop feeding the fire, the gasses will continue to burn and supply heat to the wood causing more pyrolysis and gassification until it burns itself out.
  • At this point  if done correctly, it is charcoal, pure carbon but it will need to cool overnight at the least, if it gets air it will be ash.



On a smaller scale, you can use a cookie tin with a 3/4" hole in the lid and throw it in your fire pit, this should produce the same results, only on a smaller scale.

Forgers use this method to make charcoal for their forges, it's called the Retort method which means (return, bring back).
The yield I think is 1/3rd, and is supposed to produce excellent Lump Charcoal, not that store bought crap.

Using the retort method will
reduce the amount of un-burned hydrocarbons to enter the atmosphere as opposed to simpler ways of making charcoal that are not climate friendly.  If your system releases visible smoke, that means you are allowing un-burned hydrocarbons to enter the atmosphere. Volatile organic compounds can include methane, which is much more potent greenhouse gas than CO2.

This method will capture all gases released from the biomass, wood, etc in the retort. These gases are then burned , this system will reuse these gases to recirculate the gases back into the system to fuel the production of charcoal.

You can use almost anything that will carbonize, Bones Pallets, Brush, twigs, corn cobs, pine cones, just to name a few.
Just need to stay away from treated woods and glued woods like plywood.

The most efficient way to do this is place the retort in a kiln of some sort, I do not have the resources to do this so mine will be done in a stone firepit.

The charcoal can be made into Biochar, which aids in the removal of CO2 from the atmosphere.


Hopefully I will have it built this weekend
.


The two basic methods of making charcoal that I know of are direct and indirect:

  • The direct method is the incomplete combustion of organic matter, which is to become charcoal. Combustion is controlled by regulating the amount of oxygen allowed into the burn and is stopped by excluding oxygen, smothering, before the charcoal itself begins to burn, for example: Start a fire inside a drum allow the water vapor to burn off then completely eliminate the oxygen supply.
  • The indirect method uses an external heat source in a closed chamber (retort). The vented gasses are burnt off. This is what I am in the process of making.


For you tech heads: tons of Wiki links below.


Gasification Process: The essence of gasification process is the conversion of solid carbon fuels into carbon monoxide by thermochemical process. The gasification of solid fuel is accomplished in air sealed, closed chamber, under slight suction or pressure relative to ambient pressure.

Pyrolysis: is the thermal decomposition of biomass fuels in the absence of oxygen. Pyrolysis involves release of three kinds of products : solid, liquid and gases. The ratio of products is influenced by the chemical composition of biomass fuels and the operating conditions.

Pyrolysis is a special case of thermolysis, and is most commonly used for organic materials, being then one of the processes involved in charring. The pyrolysis of wood, which starts at 200–300 °C (390–570 °F),[1] occurs for example in fires or when vegetation comes into contact with lava in volcanic eruptions. In general, pyrolysis of organic substances produces gas and liquid products and leaves a solid residue richer in carbon content. Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization.

Thus reaction is called Pyrolysis which leaves mostly carbon as the residue, is called carbonization.

Biomass:  a renewable energy source, is biological material from living, or recently living organisms,[1] such as wood, waste, (hydrogen) gas, and alcohol fuels. Biomass is commonly plant matter grown to generate electricity or produce heat. In this sense, living biomass can also be included, as plants can also generate electricity while still alive.[2] The most conventional way on how biomass is used however, still relies on direct incineration. Forest residues for example (such as dead trees, branches and tree stumps), yard clippings, wood chips and garbage are often used for this. However, biomass also includes plant or animal matter used for production of fibers or chemicals. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic materials such as fossil fuels which have been transformed by geological processes into substances such as coal or petroleum.

Biochar:
is made through a process called pyrolysis, where biomass is "baked" with little oxygen under controlled temperatures and pressures. This releases a highly useful volatile gas and leaves a charred material that is 95% Carbon. (OK, it's just charcoal at this point, and to truly become biochar, it must be put in the soil.)



October 8, 2010  Charcoal test 1 (Direct Method)

Last weekend, I did a batch of charcoal using the direct method, I was sort of just stumbling through the process. Anyhow I started with a 55 gallon drum, got a decent fire going inside with pallets then added my "Wasp Beetle infested White Ash". I had problems keeping the fire from extinguishing itself due to the fact that there were no air holes in the bottom, I knew this was going to be a battle from the beginning but due to limited resources I didn't want to cut any holes in the bottom since this barrel is going to be used as a retort.

It was very interesting to say the least, half the neighborhood was in a fog, it was one of those weird fall nights where everything seems to hang, kinda eery!

After several hours of burning pallets, I added the ash then let it burn another hour or so then capped it off. The next morning it was still hot so I let it go until the following day.

Results: Opened the drum and the burn seemed acceptable except for a few larger pieces.
I started shoveling charcoal into 5 gallon bags and did a test burn, I lit a piece with a torch and laid it on a piece of pallet, I kept thinking it was out but almost an hour later it was burning through the pallet.

Observation:
I decided to do a test burn using the chimney and then into my Reverse Flow Smoker.
A lot of the charcoal was small some would fall through the chimney starter and it took a little longer to get the charcoal burning.
The smoke coming off the chimney was chocking the fire, most likely because of the smaller pieces reducing the amount of airflow and oxygen.
I was starting to get bit disappointed in the chimney test, after about 15 minutes it cleared up fine.

After the chimney was well lit about 20 minutes or so, I dumped it into the Reverse flow, waited ten minutes then added a split to see how hot the charcoal actually was, no problem here, the split caught up immediately.
After a half hour passed I dumped an unlit chimney on top of the hot coals and that caught up as well. Overall the Charcoal performed well, burned very hot with little smoke, however I will not be using this for cooking, this test batch will only be used for starting fires in my firepit due to the fact that I used lighter fluid to keep the fire going and some of the charcoal is from pallets.


Conclusion: I can consider this a moderate success, and will be continuing with this project, unless the Fire Department shuts down my charcoal production plant.

Today I picked up the rest of the piping for my Retort and a half a dozen pallets from work. The only changes to my design is it will be horizontal instead of the original planned vertical, my reasoning is, it will be much easier to use in my firepit on its side.







 



October 9, 2010  Charcoal test 2 (Indirect Method)


I started with a modified 55 gallon drum, got a decent fire going in the firepit with pallets then added my "Wasp Beetle infested White Ash" and secured the lid. Placed the barrel in the firepit and had a decent fire by 5:00 pm.




Results: Opened the drum and had maybe an 80% success.


Observation: About an hour into the burn I could hear a popcorn popping sound inside the drum.
Water vapor was pouring out the first 3 hours. I was getting some gasification on the pipe about an hour into the burn but not around the leak in the lid but around 8:00 pm (3 hours) I was definitely getting some major Out gassing around the lid and lasted about 30 minutes.

Conclusion: I pulled the retort too soon, although I was getting no gasification, it was not ready to come off. Next time I will give it at least 2 more hours after the gas stops.
I was hoping once the gas ignited it would feed itself until all the gasses were consumed. Maybe the lid was leaking too much or I needed more heat at the top of the barrel or I needed to rotate the barrel, I don't know. I was slightly disappointed but not discouraged. I now the retort method is much more efficient, but for me the direct method is much easier, but I will decide after another Indirect burn which path I take.
I believe the Ash is not fully seasoned and may have had better success on this test if it was.

Is it worth it: For me as of now, it is, considering I have no resource to wood except for the option to buy, but in this particular case there are 2 cords of wood sitting at a friends house that is not really good for anything but an outdoor firepit and I have an unlimited supply of pallets for the fuel source. Hopefully we can utilize most of this wood into a fuel source for cooking. I will go through a decent amount of wood on my Reverse Flow Smoker, so now I can use this lump charcoal and wood, reducing the amount of wood needed for a long smoke. It can be a bit messy making charcoal and most likely will not be doing this after all the "Beetle infested Ash" is utilized.



 

First part of the video (3.29 sec.) shows some homemade lump charcoal being used.

Charcoal Retort test 2 (Indirect Method)



October 16, 2010  Charcoal test 3 (Indirect Method)

This was another test using the indirect method. I started with a 5 gallon pail drilled three 3/8" holes in the center of the lid.
Cut the wood on a band saw then chopped into small blocks,
then added my "Wasp Beetle infested White Ash" and secured the lid.
Started a fire in the firepit with pallets . Placed the pail in the firepit and had a decent fire by 4:00 pm. Removed about 3 hours later and laid on the ground upside down. See the video below.



Results: Opened the pail and had 100% success. Yield was roughly 40 percent by volume.

Observation:
Water vapor was pouring out almost immediately.  I was definitely getting some major Out gassing about 2 hours into the burn

Conclusion:
I believe the Ash is not fully seasoned and may have had better success on test 2 if it was.

Is it worth it: For me as of now  it is, considering I have no resource to wood except for the option to buy, but in this particular case there are 2 cords of wood sitting at a friends house that is not really good for anything but an outdoor firepit and I have an unlimited supply of pallets for the fuel source. Hopefully we can utilize most of this wood into a fuel source for cooking. I will go through a decent amount of wood on my Reverse Flow Smoker, so now I can use this lump charcoal and wood, reducing the amount of wood needed for a long smoke. It can be a bit messy making charcoal and most likely will not be doing this after all the "Beetle infested Ash" is utilized.

 
 
 
 Another test burn of the Lump Charcoal..
 Testing heat output in smoker.
This stuff puts out some heat!


 Chopped wood for 3rd test burn.

 Filled pail with Ash.
 Water vapor escaping.



 Gasses burning off.
You cant tell by the photo, but once the water vapor stage has completed, the gas coming out will ignite
   
 
   Finished product 33% yield by volume.
Slightly under 2 chimney fulls.


 

Charcoal Retort test 3 (Indirect Method)




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