Hi Kristijan, yes I expected the charcoal in the 55 gal. barrel on the left would be somewhat consumed during use, but I had hoped to get perhaps 2- 3, 30gal. batches made into charcoal before refilling the 55 gal. barrel with charcoal, I’m counting on the pyrolysis gas from the 30 gal. batch [via the grey pipe] to provide most of the fuel used to bake itself, after it has flowed thru the glowing charbed. Running the pyrolysis thru the glowing charbed, I had hoped to convert most of the gas into something that would flare cleanly. It may be necessary to get the thing completely warmed up before it will actually burn cleanly due to all the CO2 & moisture that is present in each new batch. …So simply flowing the CO2 rich pyrolysis gas thru the glowing charbed will not be hot enough to crack the CO2 into CO? Is that what your saying?
I am afrayd that is the case. Althugh CO2 isnt the bigest problem, water vapor is. It allso reacts with charcoal to form CO and H2, useing the energy of glowing charcoal. And there is a LOT of water in pirolisis gas.
This reactor sort of looks like water gas reactors. They have a bed of coke (charcoal) blasted with air to white hot, thain steam is put trugh the glowing coke. It reacts with it, draws the energy from it and cools it down. Then the proces starts again. This gives good guality syngas butis unefitiant becouse lots of energy is lost in that reheating cycle.
Hi Oliver, Interesting set up, but as Kristijan mentions, there are problems with it, First of all, where is the heat coming from to get the 30 gal container of biomass up to a temperature to initiate pyrolosis? When you start to heat up the biomass, there will be a lot of water comming across and damping the charcoal. Try to vent this moisture away and keep it out of your charcoal bed. Once the biomass starts to break down (pyrolisis) there will be a mixture of chemicals driven off that you are expecting the glowing charcoal to “crack” And indeed the hot charcoal will crack them, but the charcoal has to be hot, at least 1800F. The trouble is the gases will suck up heat and extinguish the charcoal. This means you will need to add oxygen to the dirty gas stream to keep the charcoal hot enough to crack the volitales, Oh, you will also need a blower to get the whole process started until enough pressure builds in the 30 gal container. Now the gas is cleaned up, run through more charcoal and then flared off in a burner placed under the 30 gal container of biomass to continue to provide heat and char the biomass.
I just feel this system is more complicated than is necessary. Why not forget the charcoal and just direct the raw pyolisis gas directly to the burner? Just seems to me there will be a fair amount of “fiddling” trying to get everything working all the while the temperatures, biomass volume, gas concentration, pressures, etc are changing. BUT, if you feel it will work go ahead and make it, That is what can be so fun about experimenting, Got to love that charcoal thought!!!
Gary in PA
OK, thanks alot to Kristijan & Gilmore & Southerland for the experienced suggestions & explanations.
I might just go with a firebrick rocket type burn tunnel instead, (removing the metal pipes & the disc brake hub) to heat the 30 gal. barrel directly, till it offgasses clear enough gasses to contribute toward baking the batch. And if I can succeed in that, perhaps then I can refine it in the future.
Gases at valve ignited in about 10 minutes. It took a total of 30 minutes of fan assisted kindling flue fire to get a self-sustaining wood gas flue fire. It burned hot and bright for another hour. When the pyrolysis flames stopped, I plugged the air inlet and closed the flue damper.
I’ll check the results tomorrow.
Yes, inside. See the picture of loaded wood above or finished charcoal below. This flexible SS was free scrap from a local stove shop leftover from relining a chimney.
Looks like the SS stands up for the job well. I am allso planing to use one of them for a heat exchanger on my gasifier but man its expensive! Althugh l think it will work great due to all the folds giveing a lot of surface area.
I get all I can use in 4" and 6" sizes. In the fall when everyone is repairing chimneys to get ready for winter cut off pieces are plentiful. My original version used regular stove pipe. Because it is in a low oxygen and low moisture environment it holds up well.
Tom,
Nails come out easy as I’m processing. About half of the nails I pull out as I’m unloading the retort. About 1/4 of them I pick out as I’m crushing and the final 1/4 come out by running a quick release pick up magnet through the sized charcoal before transferring to my container. It is hard to pass up all of the free pallets that are available. I made a pallet popper by welding bars across 2 crowbars the gap slips over the thick vertical pieces and lifts off the horizontal boards.
For the barrel in a barrel retort, I have found that placing bricks at the sides of the internal flue provides a clear path for woodgas and keeps wood away from this cooler area. Before adding bricks I would have some brands in this area.
For smokeless charcoal production consider the air sheet kiln. A thin sheet of air blocks smoke from escaping and adds air to the combustion chamber for hot clean fire. borrowed from incineration industry.
Don you are using the pyramid type system, right? How do you rate that for smoke? I saw Gilmore’s “portable” pyramid in Argos, and don’t remember seeing any smoke. I believe he was using dried wood from the mill. TomC
I have minimal smoke at start up but after there is glowing char at the bottom there is no smoke at all. The downside of the pyramid system is that you have to be there and feed it - you can’t just fill it and leave it. The upside is I can finish 10 gallons an hour all day long.
No opening on the bottom. I just built a log cabin pile in the bottom. When this starter fire was going good with the aid of the fan, I knocked it down and began adding sticks and boards. When the flames calmed a bit and ash began to show I would add another layer.
I had a solid bed of coals up to the 20 gallon level (I am using a 30 gallon drum) in two hours. So about the same rate as yours, but my feed stock may be bigger (2 inch sticks and 1X4s).
Last night was my first run so I don’t know the quality of char yet.
I lined the barrel with pieces of stainless I had lying around. Very hot fire. I had to wear high temp gloves and a face shield to feed it. I ran the fan on low with an inline speed control. The barrel was glowing a bit at the bottom at first so I turned the speed control down to the lowest speed I could get. The only smoke was from the paint burning off of the barrel.
Even though this kiln produced more char per hour, I still prefer my internal flue retort because I can walk away after getting it going.
If the char is good, this could be an option for guys with nasty neighbors.
I was surprised to see the flames travelling toward the blower outlets (see picture). The nozzles are pointed down maybe 25 degrees into the barrel. The fire is hottest opposite of the nozzles where the air is deflected by the barrel down through the feed stock into the coals below.
I will be interested to see how much ash is in the barrel. This thing has a big appetite. I estimate that I fed about 60 gallons of loose wood to get 20 gallons of packed char.
That is awesome Bruce! This is exactly what those of us in the more suburban areas would need. It looks pretty simple. What kind of blower are you using? Any chance you could upload a video?
