How to make charcoal in a home made retort
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- Опубліковано 22 сер 2024
- An in-depth explanation of how to make top-quality charcoal/biochar using a home-made retort made out of two old gas bottles. After much experimentation I've discovered this is the best and fastest method to make the best charcoal first time every time.
The plan is eventually to use the charcoal in a charcoal gasifier to power a vintage stationary engine
Hi Andy, thanks for your nice essay on how to build a charcoal retort. I like that you have used old gas cylinders as these are very robust and long lasting compared to the thin steel of the old oil drums. Old firefighting cylinders are even better as they are stainless steel and there are some large ones used for commercial situations.
There are a few of things you could do to improve the efficiency of your design. Firstly, rather than cut slots in the bottom of the fire chamber, i.e. the external barrel, you could drill a couple of rows of holes around the side at the bottom, with each row offset so that the holes don't line up. (A step drill is useful for this) Then, the barrel can just be set onto the ground and the ashes are contained.
Secondly, invert your retort so that the valve hole is at the bottom. Make the top lid just the same except don't drill a hole. You want to force the gases from the feedstock out through the bottom so that your fire will ignite them. This way, the gases are providing useable heat to your retort as they burn up the sides of the inner tank.
A row of holes at the top of the barrel and then also at the base of the stack will introduce secondary air to feed the flame and keep the smoke gases burning for a much cleaner burn.
If you are not using the thing as a heater, it is beneficial to insulate the outer barrel so that you have more heat transferred to the retort.
I reckon you could halve the burn time if you did these mods.
Once again, thanks for your video. Here in Australia, gas cylinders only have a 10 year life before regulations stipulate that they must be inspected before being recommissioned. Guess what, the inspection process costs more than than a new one, so there are lots of them going to scrap! It's a considerable waste, but for this kind of thing, a great way to recycle gas cylinders.
Hi Bruce, I agree about your ideas for improving the efficiency. I'm not sure that drilling holes around the sides at teh bottom would work so well though. I've read various things about wood needing to get air from above and burn ona bed of ash, but having tried it I can say without doubt that it burns hotter and faster if the air is comming from directly below, just like a coal fire. Also I worry the ash, although minimal, might still block up the air holes if theyw ere in the sides. At elast with them in the bottom gravity helps get rid of the ash and keep the burning surfaces exposed to the fresh air. The draw is so great that whatever ash there is mostly goes up the chimney, so very little drops on the floor.
The thought of putting holes around the top, where the main outer barrel joins the lid is a good one. It definitely needs more air in that region to burn the smoke off.
Turning the inner barrel upside down is good in theory, but not so easy in practice when using old gas cylinders. There are two main problems. First the cylinders are heavy, so the inner one is permanently attached to the outer, making it impossible to tip it upside down. I could seal the hole in the lid and make a new outlet in the bottom, but I think the lid would then need a gas-tight seal around it otherwise their would be an air path through the inner drum which might burn the wood rather than charring it. If the lid was sealed (which would be difficult to do) then it would lose the safety feature of being able to blow off if too much pressure was produced inside. I guess this could be overcome by using some kind of pressure release valve or sealing the litd in place using springs, but it's a bit complicated to achieve. If I was using good wood for the heat source then I'd definitely want to do everything to improve the efficiency. But as I'm basically burning junk (rotten wood, weeds from the garden etc) then it's not such a big worry.
Another way of using less fuel on the fire would be to cut away the bottom of the fiore grate and mount the whole unit on top of a rocket stove, which would probably use less fuel to produce very directional heat.
Now spring is here in the UK I'll do some more experiments and report back. Next step is to complete the gasifier to run an engine though.
A@@
Andy's Shed thanx for sharing your design. Maybe you can use those 2 square pipes you already welded for the gap arrangement for transfering woodgas down to burn at the bottom by drilling some holes near the grate and adding 180 turn abit smaller square tubes for each like tight sockets on the inner cylinder lid. this idea might be usefull for you. more heat, less time, less fire woods.
Best charcoal making vid I've seen 😉. Love your design and use of old equipment. Recycled stuff is always a winner.
Thanks. I'm glad you enjoyed the video. There will be more about biochar coming soon. I'm currently building a gasifier to run sn engine on the charcoal I produce.
Andy's Shed ... Now that I must see 😉 Hydrogen powered!
I've subbed so won't miss any, I look forward to seeing more great ideas and builds 👍
I've seen a few of these videos and I got to say you are best with the design and instructions. The end is all charcoal and plenty of it. Top marks
John H Thanks John. What you see in the video is the simplest design that works well. There are enhancements you can do, such as insulating the outside, but they're not totally necessary.
Outstanding! This is cheap, easy to build and very efficient. Thank you and greetings from Oklahoma.
Thanks. It's good to know you enjoyed the video.
Mike, are you a chickasaw plum grower or do you just harvest them wild? Do you have any trees that are especially outstanding (especially large fruit, better taste...)?
Brilliant video, very informative and explains the process very well. I’m going to try this myself once I find some cylinders.
Huh, best design I've seen so far. No way for a tar/gas/ect-junk to build up and block something for an explosion. I'll give building one a go!
Yes I don’t mean to bring controversy over repurposed pallet wood. I was making a observation and it was a question I’ve had for years, without answer. Because the Chinese Asian Beatles and other invasive species are having havoc on the globalization process. I don’t think our global ecocide is actually worse than our global invasive species problems. FYI in Italy thousand year old buildings are being literally eaten from China’s plants that came from the “made in Italy” shoe industry. That and the Corona virus hit Italy because they have Chinese workers commuting there. Many thanks for your video, it’s awesome bio coal burning information.
No problem. It's a good question and something I have never really thought about.
you, my friend, are top notch.
i am researching retorts with a view to building my own.
i think i found a winner here.
would live ti see it running
Thanks Paul. I tried the Hookway retort and the double barrel method before I tried this. Neither of those worked as well as this does.
I cant see any retort beating this one. Not without some kind if tech being involved anyways. I'm going to build this.
3 thumbs up my friend!
Give it a go. I'd be interested to know how you get on. You can drop me a line at andysshed.callpress.net
Thank you for sharing with us. I really like your setup and i have exactly the material to make one like yours. I will use the charcoal for cooking inside a Camado BBQ. Best regards from Canada
Good luck with your build. Let me know how you get on.
The older the nail, the harder it is because of wood shrinkage and the metal swells from oxidation from moisture in the wood, makes for a very tight fit. Its why when you pull wood off, the nail pulls out though the wood and the nail is still sticking out the other part its nailed in to.
Great job, only one thing I would change, make the charcoal bin easier to retrieve the charcoal by a chute or maybe lifting the bin and dumping it.
I'm not sure how a chute could be added and still keep the thing airtight. Lifting out the inner barrel would work, but because it's an old gas cylinder it's quite heavy, even when it's empty.
@@AndysShed a drop door/chute combined, drop the door, it becomes a chute.
The best video about diy charcoal making I've seen so far. Congrats. Question: how easy it is to take the charcoal out the inner barrel and would it be worth trying to improve that?
If you cover it with muddy fabrics or fibers, efficiency will increase couse of not losing heat much. It is basically covering with durable mud surface.
That's a good idea. I'll try that.
I imagine the wood gas burning at the top helps burn off smoke and make it cleaner over all.
I gave you a like because I like the way you explain it and show what you did. Very well made video. I never knew you could use charcoal for gardening. I sometimes come across chopped trees and didn't know what to do with it. I wanted to cook with it. I've seen other just store the chopped wood in a make-shift shed until it dries out then they use it, but this would be a lot better.
Seen a few, best yet, thankyou good luck
Very nice bit of construction. Great burner. Just thinking wouldn't it be better to have the gas escaping from the bottom of the inner chamber? Thus the burning wood gas would contribute to the heating.
In theory you're exactly right. However that would mean having to seal the top somehow, which in turn would greate the need for an emergency pressure release valve of some kind. If the top wasn't sealed and there was a hole in the bottom, there would be a path for air to go through the retort and it could be enough to turn at least some of the wood inside to ash rather than charcoal. What might be possible is to take a small pipe from near the top of the inner barrel, out through the side, down the outside and back into the burn chamber. That would keep all the holes near the top and so there would be no air path inside. I'll probably have a go at that sometime when I get around to it.
@@AndysShed After I made that comment I saw that as the problem... seems a shame to waste that energy in the wood gas. Something to solve.
I would think that you would want to have it gas-off into the bottom of the outer chamber that way you get full retort and don't have to use as much wood, if any to keep it going. Otherwise, I like the heavier gauge materials used for durability.
You're right about ideally getting the gas into the bottom fire chamber. I'm just working on the best way to do that now. Watch this space for an updated design!
You need to put the inner retort in that thing upside down so all the burning wood gas and volatiles work in your favor to further heat the retort instead of just pissing all those tens of thousands of btu's into the air..
Just saying.. otherwise excellent job 👍
Unfortunately I haven't found a way of putting the retort in upside down because it's fixed to the sides of the outer barrel with stand-offs, so doesn't come out. However I'm looking at taking a small pipe from the side of the inner retort near the top, through the outer barrel and back down into the burn chamber where it could be lit, which would effectively do the same job. However the problem then becomes how to seal the lid so all the smoke is forced down the pipe. I definitely agree with your thoughs though.
@@AndysShed Might also run into a problem where the first dirty gas/moisture/tar clogs up the small pipe. Would need a bypass opening with weighted seal (large steel ball?) to allow first dirty gas to escape before routing it down thru the pipe to firebox. Should small pipe clog the weight ball would allow expansion of gases to safely release.
Great video, keep it up!
You should check out HOW the " old timers "( Farmers ) , used with wood to run TRACTORS
It was in Europe some tractors and cars runned on woodgas during WW2 with a lack of fuel.
I’m just wondering if pallets are treated with pesticides because of exports. It’s a wonderful video. And I hate to mention it... regardless the pesticide would probably be burned off.
I doubt they are treated with anything. Lots of people burn pallets and some even build sheds or household furniture out of them. Some pallets have also carried food, so I doubt there would be anything that would be in any way dangerous.
I guess you can’t use pallet wood for BBQing though as it’s pine? Decent set up overall and well explained. I think I’ll give it a try but using hardwood instead. I might use pine for bio charcoal for the garden.
Some pallets are pine, but others are hardwood. It's easy to tell the difference from the weight. I don't use the charcoal for barbecuing. My plan is to use it to power a vintage petrol stationary engine using the gasification process. Watch this space for a follow up video showing my home-built gasifier and how it's connected to a single cylinder engine.
Most pallets are made out of Cottonwood not pine
I like your video, great work. I have a question, will it be more efficient by burning it horizontally than vertically as it burns more evenly.
That's a very good question! Unfortunately I don't know the answer. Wood burning stoves certainly work better horizontal. I think the fire would still need to be below the charcoal though. It would probably need to be a ling fire burning the entire length of the charcoal barrrel too.
Great ......................Cheers
Love it
You can boast with the nails in there, of producing - "Iron fortified charcoal" as well as "hardened nails".
Do work on redirecting the wood gas to the bottom for more efficiency regardless of the fuel (I think anyway). Waste not, want not. An additional (modulated) air inlet at the bottom should add efficiency and reduce the smoke even before the wood-gas kicks in making it a much cleaner operation. My 2C anyway. Nice idea though, I do like it..
I'm planning some modifications, one if which will be a pipe from the top of the inner Barrel down into the fire box to try to use that gas or at least burn the smoke off!
If u just put rails down the sides then you could pull the barrel into and out of the outside barrel. which make it Easyer to Load and unLoad
It's actually quite easy to load and unload as it is. It's justbthe right height to reach into and pull the charcoal out. I did originally have a removable inner barrel, but when it was full of wood it was too heavy to lift into the outer one, especially with having to lift it quite high.
As it is I can just comfortably reach to the bottom of the inner barrel.
One backdraw of the design, is how to extract the charcoal from the inner cylinder!, I belive it will be hard to extract from that depth
did you use softwood to make the charcoal
It was probably a mixture of wood. It was just anything I hay laying around.
Brilliant, ta!
Give over, How does it connect to the flux capacitor?
I know this is from several years ago but I would like you to send me a jar of powdered char. I live in Adelaide South Australia, I'm 70 years old and would love to sample some of your finest char. I will pay for shipping and of course a container, maybe 1 kilo, that's if it's not too expensive. Thank you. I liked and subscribed.
Thanks 👍 Andy, I have one question did you put any holes in the bottom of the inter barrel? I been looking at how to build a reliable biochar processer. I am looking forward to building this one!!
Hi David. No, definitely don'y put any holes in the bottom of the inner barrel. If you did there would then be a path for air to enter at the bottom and go out the top, which would allow the wood to burn away rather than turn to charcoal. If you're interested in using the gasses driven off from the inner barrel to help fuel the fire, then you can fit a pipe (steel would be best) to exit the inner barrel at or near the top, then bring it down the outside of the outer barrel and back into the firebox area. That would then take some of the gasses back down to the fire. But whatever you do, make sure you don't fasten the lid of the inner barrel. This needs to be able to lift just in case there is a large build up of gas that needs to escape.
@@AndysShed thanks for the advice, I really appreciate it! Looking forward to building mine this spring!!
Duuuuude, you look like Ben Franklin.
A mixture of Ben Franklin and Ron Jeremy
Hey Andy,
Do you have measurements or dimensions of the retort? would love to try this. Thanks for the video
Hi! I didn't make the retort to any particular dimensions, so I don't have measurements. It can be as tall as you like, needs enough space underneath to make the fire and a gap betweeen the sidewalls of an inch or maybe two so the flames can reach up the sides.
@@AndysShed ok thanks
so you can put any wood into the inner barrel.. 2 x 4's will work as well, BUT, can u barbecue with the 2 x 4 charcoal, is it ok to eat barbecued food from 2 x 4 charcoal, or will it have a weird taste?
I think once it's charcoal you've burned off most impurities, so it won't have a weird taste. An untreated 2x4 is just a piece of wood like any other piece of wood, so I'm pretty sure it would be ok. The only think you might need to be careful of is if you're making cahrcoal out of old timber that has been painted and teh paint has lead in it. What I do is use clean timber in the retort to turn into charcoal and any painted, rotten or otherwise dodgy stuff I burn in the bottom as the fuel for the process.
hey thanks for your time and wisdom, thats a good point regarding iffy wood to be used as the fuel wood.
P.S. I have recently removed the internal tank from a 40 gallon gas water heater.
Its too big for a forge, and I was wanting to use it as a retort BUT the center pipe that runs the entire length of this water tank is of a smaller diameter than 4" diameter heating pipes on youtube charcoal retorts! ( The water heater heats up the water in the tank by utilizing a burner at the very bottom of the water heater.. The burner heats up the bottom of the water holding tank directly and also all heat is directed upwards through the center pipe which is installed in the center of the water tank. Natural convection and fire and heat travel up the pipe, heat the pipe, and therefore transfer that heat to the water which surrounds the center "chimney" pipe!
SO- can a retort still be successful and function well with a smaller diameter heating pipe?? So long as I am on top of adding fuel wood and keeping the fire HOT?
If I've understood this right, what you're wanting to do is send the heat from the fire up a central tube inside the retort (a bit like a rocket stove) rather than round the outside of the retort as I did.
While this method does work (James Hookway has some good videos doing something similar) the tube up the middle needs to be quite big to give enough surface area for the heat to transfer to the charcoal chamber. You would also definitely need to insulate the outside because otherwise there would be wood right up against the cold outer skin and that wood probably wouldn't char.
What you could do would be a hybrid design where as well as the fire burning up the central tube it also goes up around the outside like mine. The problem you'll have is finding a way to make an opening to load the retort with wood and also being able to almost seal it , so basically no air gets in but pressurised gasses can get out. This is a problem with the Hookway retort too.
I did try a small Hookway type retort and it didn't work too well for me. It might be that it works better if you build it bigger though as mine was quite small. I also found it difficult to make a sealed lid for the charcoal chamber.
If you try any different designs be sure to let me know how you get on. I'd be very interested to know.
the hookway version uses less wood.
I think the Doorway only uses less wood because the gasses given off from the inner retort are piped back down into the burn chamber to help with the heating, which also helps control the smoke given off. It's been mentioned before that I should run an iron pipe from the top of the inner barrel, just below the lid, through the outer barrel, down the outside and have in enter back into the burn chamber. It's a modification I intend to make, I just haven't got around to it yet. I guess it's more of a concern if your fuel supply is limited. However I burn all sorts of rubbish in the burn chamber, not just wood.
The problem with a Hookway, which has the chimney up the middle, is finding a good way to seal the charcoal chamber around the outside. I'd be worried about it sucking in too much air from the top and turning the wood to ash rather than charcoal. I'd be very interested to know how others have got around the seal problem.
@@AndysShed I'm building one at the mo and everything will be welded and I will use water to quench when the gases stop coming
@@mikha007 I'd be interested to know how you seal the chamber with the wood you want to turn to charcoal, Doorways usually have a round top with a hole in the middle for the flue pipe but I've never worked out how to seal it so the gasses given off can be routed back to the burn chamber efficiently. That's the main reason I put my flue around the outside, so the inner barrel could have an ordinary lid.
@@AndysShed not all of your comment came thru but the rocket flue passes tthru the top of the drum containing the future charcoal.the bottom of that barrel has a detachable lid which can be released to exit the charcoal.everything is sealed.
however the pipe which allows the wwoodgas to go to the burn chamber needs to be shut off if you're not dousing with water when the gas is totally consumed or else oxygen can re ignite the freshly made charcoal. the vent at the top also needs to be plugged
How do you get the charcoal out of inner container does it lift out? How easy is that
No, it doesn't lift out. There's no reason it couldn't be made to do that, but the cylinders I used are pretty heavy, so I just made the whole thing solid. I just reach in and grab the charcoal chunks. I like to snap them in two anyway to make sure they're done. If they don't break then they go back in with the next batch.
I have an outdoor wood fired water stove with a large firebox, approximately 24"x24"x34". Do you think I could make a metal container to set inside my water stove firebox to make charcoal?
That sounds like a good idea to me. The key thing to remember is the container has to be almost air tight, just with a small hole to let expanding gasses out. I've heard of a lot of people using large paint cans with a small hole in the lid. You can't produce much charcoal that way, but it proves the concept. Just throw it on your fire and when flames stop coming out of the hole the reaction is done and the gasses are all burned off.
@@AndysShed Thanks so much (and apologies if I shouldn't be clogging up the comments with just a thank you, but I really appreciate it.)
No problem. Comments are always welcome. Let me know how you get on with your charcoal making.
@@AndysShed I'll try to report back. I'm thinking of going with just a 5 gallon propane tank and using it very much like you did, except in the firebox of my outdoor water stove. That's a little smaller than I might prefer, but I build a fire every few days throughout the summer to heat my hot water anyway, so multiple small batches of charcoal shouldn't hardly be any more trouble for me, and that should add up to all the charcoal I want to make for now anyway. I've gotten one propane tank I can use already and just need to find one more. Thanks again!
@@AndysShed Following your idea here but making use of my outdoor water stove firebox for the outer chamber I've now made about a half dozen batches of charcoal, and it's working great. If you're interested, and if you can recommend a way to do it, I'll send you a photo of it in operation. I can open my firebox door and see the flames shooting out the top of the propane tank. I'm loving it. Thanks again!
First off GREAT SIMPLY GREAT -- But as far as not using for a Gas engine because it is to HARD to clean Here is an EASY WAY TO CLEAN THE GAS **** RUN THE GAS ONTO A Double PEE TRAP like in plumbing u fill the first with water then the other end is the gas exit ,as the gas is DRAWN through the water , debris is left behind in the water ..bottom plug for cleaning --- ( just example ) but you get the Idea
This device is just for making the charcoal, not for producing gas to use in an engine. I'm currently building up enough charcoal stocks to start experimenting with a simple gassifier to produce the gas. The idea of using charcoal rathet than wood is that in the process of converting the wood to charcoal most of the tars and other nasties have been burned off. So charcoal will burn much cleaner in a gasifier than tjomgs like wood pellets and so won't need anywhere near as much filtering. Yes, you've lost some energy in the conversion, but that is balanced by not having to carry around huge filters as part of the setup. A simple open cell foam filter in something like a large coffee can should be enough for running a small engine.
Is there a trick to emptying the barrel? Can you turn it over to get all the charcoal out?
There's no trick. I just put my hand in, grab the charcoal and drop it into a bag. The whole thing could be turned over, but it's quite heavy. Picking the charcoal out also has the advantage of leaving all the fine dust in the bottom of the barrel to fetch out seperately.
@Whoop!!!
Wouldn't pallet would be treated?
Not normally. A pallet is cheap and disposable. Any treatment would be an unnecessary cost in the manufacturing process.
What size are the cylinders? Is the big one 48kg and the inner a 13kg?
Sorry, I have no idea what the sizes are. They are just scrap cylinders that I was given. The outer one was about 5 feet tall and the inner one about 3 feet. The dinensions are not critical though provided there is enough space under the small cylinder for the fire and there is at least an inch of clearance all round inside the large cylinder so the flames and heat can rise up between the two.
in the uk it would be a 47kg and a 19kg
Great video Andy and really well explained. I’m already searching for a couple of old gas bottles to get started with. Thanks for taking the time to share this idea with us all. As one youtuber already mentioned it’s much sturdier than the 45 gallon drum versions you see out there (in my opinion).
Cheers Pal, nice Vid.
Is the outer cylinder hollow at the top and bottom?
Yes, there's a space at the top for smoke and flames to move over the lid to escape up the flue pipe. The bottom of the inner Barrel is also about 6-8 inches off the bottom of the outer because this is the combustion space where you put the fuel you actually want to burn.
if you pack the space with waste wood and light it at the top it would be less labor
It's a good theory, but I've found by experimenting that it doesn't always work in practice. If you fill the space with wood and light the top what tends to happen is the very top burns, but because heat rises not enough heat transfers into the lower wood for it to ignite. Also when top lit, air is being drawn upwards, which also tends to stop the wood burning downwards. It might work if the space between the two barrels was bigger, but that would require a lot more wood than I'm using in the video. The other thing is that heat rises, so to get the maximum heat possible transferred into the inner barrel the burn is better to happen at the bottom to heat the bottom of the inner barrel, then it also heats the side with an effect similar to a rocket stove.
The TLUD system needs more wood and the wood has to be totally dry (which here in the UK it very often difficult to achieve). This bottom burning system can use slightly damp wood if necessary. You can also burn other home and garden waste. The down side, as you rightly point out, is that you have to keep feeding the fire. However I was more cnncerned with using less wood and wood of lower quality than being able to leave it unattended.
The other down side of a TLUD is you will often get 'browns' left behind because the fuel has run out around the barrel before the entire inner contents have been turned to charcoal. If you run my system for long enough (mine takes 2-3 hours from lighting) everything gets totally converted because you can add extra fuel as necessary.
drill holes around the base of the chimney
I'm going to try that. I did try someting similar where I put two steel rods under the chimney section to hold it off if the retort about half an inch to let air in there. It made it more difficult to light and it didn't draw the fire as much. My guess is I was letting in too much air.
Could you use sawdust or shavings?
Hi Phillip. You could certainly use them inside the barrel to make the biochar. When making charcoal the idea is not to let any air get to the wood you're trying to char, so sawdust would proabbly be really good and it would come out as fine dust for garden use. However as I'm personally making the charcoal to run in a charcoal gasifier, I need to use something a bit more chunkey. But for garden use it would probably work ok. The thing is don't pack it in too hard because it's a really good insulator and it might stop everything charring right to the centre of the barrel.
Shavings would also work well to start the fire. I think sawdust would probably choke the flames though. But if you have sawdust you want rid of, just sprinkle some in there little and often.
👍❤️👍
Do not retort.