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BIOMASS => General => Topic started by: Bodidly on June 30, 2015, 02:02:04 PM



Title: Ideas wanted on building a charcoal retort.
Post by: Bodidly on June 30, 2015, 02:02:04 PM
Hi all. Wondering if any of you have any bright ideas on how to build a retort. My current one is steel and works great but the steel is not going to last long with the temperatures involved. I have looked into fireproof bricks but they are too expensive for something as unprofitable as making charcoal.

This is my current set up to give you an idea as to what is needed.
https://www.youtube.com/watch?v=ceJap39Qwro

The barrels work fine and are cheap enough to replace but the outer chamber takes a hammering with each burn and is buckling more and more. I do need to put a front on during the burn but some old corrugated sheets would probably suffice. Be intrested in any lattaral ideas you all might have.


Thanks  :)


Title: Re: Ideas wanted on building a charcoal retort.
Post by: garethpuk on June 30, 2015, 10:16:08 PM
Looks like it's an old water tank? Was it fairly thin to start with? I'm no expert on making charcoal but something makes me think the retorts are usually quite thick steel and round? (just been watching grand designs and Ben law was making charcoal)

How about finding a local engineering firm who could roll some say 4 or 5mm plate into a tube and weld the seam

Is stainless more heat resistant? Maybe some sort of scrap stainless tank with the ends cut off to leave an open bottom and to use as a removable lid, an ex dairy tank any good?

Possibly more random thoughts to follow! ;D


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on June 30, 2015, 11:03:34 PM
I like random thoughts Gareth  :)

You are quite right about it being an old water tank but is a fairly heavy plate. Yes steel is the convention but does fail over time round or square. There is a production retort in heavy round steel that I know needs beating back into shape after a few hundred burns. Not sure on stainless and had considered looking for some sort of scrap dairy tank but most of the local scrap boys have pretty clear yards and leave little to pick through.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: renewablejohn on June 30, 2015, 11:35:55 PM
Your ideal solution would be a thermal oil rotary plate dryer but there soooo expensive even 2nd hand.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 01, 2015, 03:25:31 PM
Yes can't spend too much John. This is not really a serious business if you look at the hours involved more a hobby that makes a few quid.

Had wondered about building a brick kiln like a giant pizza oven. Fire bricks are very expensive but apparently some clay bricks cope with fairly serious heat due to the way they are made. Any comments on that?


Title: Re: Ideas wanted on building a charcoal retort.
Post by: smegal on July 01, 2015, 03:32:52 PM
Yes can't spend too much John. This is not really a serious business if you look at the hours involved more a hobby that makes a few quid.

Had wondered about building a brick kiln like a giant pizza oven. Fire bricks are very expensive but apparently some clay bricks cope with fairly serious heat due to the way they are made. Any comments on that?

What about using cob instead of bricks? (minus the straw) maybe reinforced with something like this.

http://www.ebay.co.uk/itm/230867481610


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 01, 2015, 04:54:33 PM
Off to look up cob now. Thanks smegal


Title: Re: Ideas wanted on building a charcoal retort.
Post by: desperate on July 01, 2015, 05:08:43 PM
Howsabout build a kiln out of ordinary thermalite blocks and have a cast iron pipe going right through it so timber could be fed through the pipes and the charcoal would drop out the other end. If you rendered up the inside of the thermalites with a fire cement render that would be good for at least 1200 degC. Not quite sure how you would stop the charcoal burning inside the pipes though, maybe a batch system with loose fitting plugs at each end?

Sounds like a good fun project to me ;D ;D

Desp


Title: Re: Ideas wanted on building a charcoal retort.
Post by: smegal on July 01, 2015, 05:29:40 PM
Off to look up cob now. Thanks smegal

I have no idea what temperatures it can take, but may be worth a look. People seem to make pizza ovens from it.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: mr_magicfingers on July 01, 2015, 10:12:43 PM
was just contemplating a charcoal retort today as I walked through our wood and looked at the old coppice. Was wondering if a rocket stove would work, built around a barrel


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Philip R on July 01, 2015, 11:08:24 PM
If you are travellingnear the Scottish borders take a couple of hours and visit the gas works museum in Biggar. Very interesting.

BTW why make charcoal, does not sound very environmentally friendly!! Just burn the wood cleanly..

Philip R


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 02, 2015, 07:34:07 AM
If you are travellingnear the Scottish borders take a couple of hours and visit the gas works museum in Biggar. Very interesting.

BTW why make charcoal, does not sound very environmentally friendly!! Just burn the wood cleanly..

Philip R

I get your point but we use the small branch wood that in the past we would have been burnt up in a brash pile in the field. A retort is much cleaner than a traditional ring kiln and imported charcoal well don't get me started on that  ;)

Thanks for the tip on the Biggar museum.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Greenbeast on July 02, 2015, 10:14:35 PM
i was going to suggest fire cement, or a castable refractory lining
Still might be pricey though for that size (would need a few inches thick i would think)


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Warble on July 02, 2015, 11:47:28 PM
Why not dig a pit then you would only need to cover the top.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: roys on July 03, 2015, 01:16:52 AM
Not sure but do you not need combustion air feeding into the base ?


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 03, 2015, 07:12:44 AM
Why not dig a pit then you would only need to cover the top.

Need to load with the tractor and our water table table sometimes reaches ground level. I started by digging into a bank but when the earth got hot it turned to dust and literally ran into the fire down to a surprisingly low angle.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 03, 2015, 07:14:20 AM
Not sure but do you not need combustion air feeding into the base ?

Yes it burns a LOT of air when at full tilt.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 03, 2015, 07:15:53 AM
i was going to suggest fire cement, or a castable refractory lining
Still might be pricey though for that size (would need a few inches thick i would think)

Will look into castable refractory lining but suspect it would be as expensive as using fire bricks.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 03, 2015, 07:20:32 AM
Off to look up cob now. Thanks smegal

I have no idea what temperatures it can take, but may be worth a look. People seem to make pizza ovens from it.

Did read a bit about cob. Seems that there are many different types of clay and some are not suitable. Sounded like samples need sending off for analysis to get it right. Sadly we have no clay of any sort on the farm. Would be nice though.


Sorry to be negative about the suggestions so far but keep em coming as it's much appreciated

Beau


Title: Re: Ideas wanted on building a charcoal retort.
Post by: billi on July 03, 2015, 07:39:47 AM
... i guess , i would  go  Smegal s  route as well  ,  and built a dome / pizza oven style  out of clay/subsoil  and reinforcement material init  , like cop ,   straw can be replaced or additional reinforcement like chicken wire / re-bar  added

I mixed my own subsoil    with sand and grid , and straw  shreddered with our Kenwood smoothy maker (bless him  rest in peace)  and  some imported clay powder


A dome structure   can be   built easy   out of rebar and chickenwire  and the clay plaster  added to the structure  after ,  or one mounts sand or  on site earth  to a dome  and casts the cop mix over it  and digs out the mount under the dried out shell after .....


Other idea ..... 5 mm thick Metal   (mild steel ) is costing about 50 Euro per m2  , a welder ......

Billi


Title: Re: Ideas wanted on building a charcoal retort.
Post by: Bodidly on July 03, 2015, 08:00:43 AM
Love the image of you mixing it all in a smoothy maker  :hysteria How long did it last?

Does sound like there is some mileage in the cob rout if I can get my head around how to do it. Shame it's such a large first project in it. 5mm steel will give up the ghost in time. The frame the barrels sit on is some 5mm thick angle and glows cherry red then bends. A pic of the first frame in 3mm angle after one burn. It gets hot in there


Title: Re: Ideas wanted on building a charcoal retort.
Post by: billi on July 03, 2015, 08:27:17 AM
..... did the job ,    for shreddering the straw   for the clay plaster of our  35 m2 extension   building ,  ... cant remember  if its  still working ,  but  somehow  he never made it back into the kitchen .... whistle

It worked quite well , cause the straw ended up in fibres  similar to strong hair , ....  so smoother than raw straw





(http://s2.postimg.org/dqhed16r9/clay.jpg) (http://postimg.org/image/dqhed16r9/)


Title: Re: Ideas wanted on building a charcoal retort.
Post by: smegal on July 03, 2015, 10:02:49 AM
Would storage heater bricks take the heat? They may be cost prohibitive for making the whole thing, but could work as supports for the barrels.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: chasfromnorfolk on July 03, 2015, 10:38:35 AM


Does sound like there is some mileage in the cob rout if I can get my head around how to do it... It gets hot in there

Sorry for the negatives, but if you do go the cob route, maybe reinforcing is not a good idea. I'd guess multi-directional expansion and contraction of the rods or mesh would crack the clay open. You'd need to put a roof over it too... rain on clay, even baked clay, is known in pizza-oven circles as ruinous.

Chas


Title: Re: Ideas wanted on building a charcoal retort.
Post by: mr_magicfingers on July 03, 2015, 10:51:38 AM
I wonder if putting a coat of lime render on the cob would protect from weather, seems to do so for the houses round here. It's what I'm planning to do when I build my pizza oven.


Title: Re: Ideas wanted on building a charcoal retort.
Post by: chasfromnorfolk on July 03, 2015, 06:07:39 PM
I wonder if putting a coat of lime render on the cob would protect from weather, seems to do so for the houses round here. It's what I'm planning to do when I build my pizza oven.


Don't think so...lime rendered cob walls are deep under overhanging eaves away from much direct rain. Admittedly not much rain sticks to a dome, but lime render isn't waterproof enough for exposed cob. Either use brick for the dome instead or render with a modern product like K-Rend. Even that's not waterproof.

Sorry, off-topic-ish.

Chas


Title: Re: Ideas wanted on building a charcoal retort.
Post by: mr_magicfingers on July 04, 2015, 09:02:49 AM
I wonder if putting a coat of lime render on the cob would protect from weather, seems to do so for the houses round here. It's what I'm planning to do when I build my pizza oven.


Don't think so...lime rendered cob walls are deep under overhanging eaves away from much direct rain. Admittedly not much rain sticks to a dome, but lime render isn't waterproof enough for exposed cob. Either use brick for the dome instead or render with a modern product like K-Rend. Even that's not waterproof.

Sorry, off-topic-ish.

Chas

Thanks, will look at K-Rend for when I build my oven as there won't be a roof over it.