You really ought to try charcoal screened 3/4 inch down to 1/4 inch as that is the recommended size for charcoal gasifiers.
11 Likes
I totally agree Don. I’ll have to get some properly sized screens next time I go to town. I only go twice a month so I just couldn’t wait!
6 Likes
Marty, put your charcoal in a small barrel shake it and bang it to cause viberation. The fines will settle to the bottom take the charcoal off the top and use it.
The flare looks good. Congratulations on your build.
Bob
2 Likes
Well, I guess this is a two step forward, one step (or maybe two) back report. I rearranged my gasifier to take out the large volume hot filter and went directly to the radiator from the cyclone. I was leery about tars condensing in the radiator while using wood and being a bitch to clean, but now on charcoal that isn’t an issue anymore. I plumbed in a small foam filter after the radiator.
I screened my charcoal and did another run. I had a tough time again getting a sustainable flare. Mainly I think it was the charcoal being too wet again. I got more water out of the radiator tap than I expected after only running about an hour.
My foam filter was a bust. It did a great job of filtering the gas, but there is too much stuff making it past the cyclone. In addition, it was wet and formed a paste on the foam which probably did a good job of killing the gas flow.
The cyclone stopped probably 90% of the particles, but I can see I will have to increase my filter area to keep the loading from restricting flow.
Another issue is that I am dropping a lot of unburned charcoal through the grate into the bottom of the gasifier.
So I have several questions:
Since it is difficult to control moisture in the feed charcoal, should I just use bone dry stuff and add a water drip? What parameters do you use to determine flow rate? Temperature?
Can I use a smaller filter like mine if the filtered stuff is dry? Will it fall off the filter if I vibrate the filter?
Is it normal for so much charcoal to make it past the grate? I opened the cleanout door in the middle of a run (carefully) and noticed that at the bottom of the restriction cone there was no burning charcoal. Should the burn extend to the grate?
I look forward to any suggestions.
Thanks!,
Marty
5 Likes
Marty I’ve had issues with foam, a filter using sawdust has worked very well for Matt.
He suggests to put hay or pine straw or some other loose media at the bottom and then put the sawdust over that. The outlet has a screen to prevent the engine sucking in sawdust.
Also for moisture, maybe it would benefit you to add a condensate gutter to the hopper for excess moisture to leave. It also will help if you decide to run it as raw wood.
One more thing about your cooler, in that vertical style it’s best to run from bottom to top, moisture will drip down and rinse the pipes as it condenses.
As for your grate, how far is the distance between the bars of the grate, or size of the holes? I think with the size range we use here 3/8" gap is sufficient for engine grade charcoal.
The distance of the burn depends on how hard your engine or blower is pulling on the gasifier. I want to say if you see it actively burning at the grate you’re over pulling it, you want a distance of charcoal where the oxygen has been totally consumed and can scrub the gas.
4 Likes
Looking at the grate the charcoal passing through is the size open of the grate.
If you were burning a flame down to the grate you would not see the bigger charcoal. It would be more ash. 10% moisture is what you should be burning with out a drip system. Having wet chargases is okay. Is looks like it is condensing in your cooling tubes. Yes the surface area of the filter looks to small and is clogging up. Have you tried a wood chips/sawdust filter yet after the cooling tubes? They are easy to build.
Look up @Matt Matt Rider, he shows some nice wood chip/sawdust builds.
Bob
2 Likes
Thanks guys,
Good ideas on the filter.
I have 3/8" holes in the grate, about 60 in a six inch diameter plate. What I don’t understand is how the ash from higher up gets through the unburned charcoal below it. I do have to shake the grate every couple of minutes to keep the flare strong (when it was working a couple of days ago). The fan speeds up a bit after the shaking indicating to me that the ash was clogging the passage ways between the coals?
I guess shaking the grate lets the unburned charcoal drop out with the ash above it? I’m just wondering if this is expected to get so much charcoal in the ash pit.
Marty
4 Likes
Every time you shake the grate char will drop through. On my news grate it is a slotted V and the spacing is 5/16". I am hoping not to have to shake it. It is 15" with a 8" coming out the bottom of the restriction charcaol reserve. This charcoal/wood gasifier will be running a 5.2 liter engine. I want to see char bits in the bottom of the ash area. It is no big deal because I just reuse the char again after screening it.
Bob
3 Likes
If you look at my char dump videos on both the toyota and the dodge, you will see that I DREAM of so little ash coming through the grate on my trucks 
I can fill a feed bag cleaning out the char after 3 days of driving the v10, same after 6 days in the toyota
5 Likes
Thanks Bob and Marcus,
As a newbie to this art, I was afraid I had an issue contributing to the flare problem with the char falling through the grate. It’s good to know that this is expected.
Bob, as to moisture levels in the charcoal, how do you measure it and how do you prepare the charcoal?
Out of a retort or fire pit I would expect 0% moisture in the charcoal. If I douse it with water and let it dry like firewood, would I expect it to be in the 10% range? The problem I foresee is that unless I spread it out, it would remain a damp mass in a barrel or container.
Marty
2 Likes
Marty you could just suffocate the charcoal to put it out. Take a metal drum or trash can with a lid and lay the lid on with a brick to weigh it down, don’t lock the lid down with a ring clamp because you want it to release any pressure.
Usually when someone is adding moisture to the charcoal they do it by weight. Charcoal will absorb moisture from the air over time if you’re in a humid environment like I am.
5 Likes
Like Cody said, I never douse my new charcoal with water. As charcoal cools in a covered barrel overnight, it also cooks some remaining brands, if any. The only reason I would douse with water is if I am making bio char for the garden when the cold water shocks the char giving more surface area.
6 Likes
Thanks Cody & Don,
I think I will bake some wood in a barrel to make charcoal. So do you guys add any water to the charcoal in the gasifier? Or has it absorbed enough from the atmosphere by the time you use it?
4 Likes
I like to add water 15% by weight.
4 Likes
Marty the way I make charcoal is to just simply burn the wood in the barrel. Start a fire in the barrel and slowly feed the fire. If you can safely tilt the barrel at a 45 degree angle it will make the charcoal faster.
Make sure there are no holes in the barrel or else air will get in and consume the charcoal.
I use branches about 4 to 5 feet long so it feeds itself, falling into the barrel as the charcoal crumbles. When I have the barrel filled up or I run out of wood, I put the cap on it and leave it shut for at least a day. Hot charcoal will re-ignite if air is reintroduced.
3 Likes
Marty if I wet my charcoal to put it out. I will dry it on a tarp on a slighty sloping ground. Good old evaporation and sun light. I cover it up at night, or you can let the rain wash it some more before drying it. I like doing it this way the best. I pull my hot charcoal out of the retort or fire pit and into a basin of water. This washes the ash away. Becareful of the water, you are making lye ash and sluge. The charcoal will be less dusty, then if you just screen it and bagging dry, after putting it in a air tight container to put the charcoal out and cool to cold charcoal. In the winter months I put it in a air tight container to cool down completly, because of the freezing conditions. Frozen charcoal just stays frozen wet.
I have a barrel retort that I can seal off the incoming air and cool the charcoal. I leave it set for a couple of days to make sure the charcoal is completly out and cold.
The name of the game is trying not to be covered in black charcoal soot dust on the face, hands and clothing when making it.
Bob
4 Likes
This is a game I have yet to win
6 Likes
Same here for me. A shower at the end of the game.
Bob
5 Likes
marty, on my blue mower the reduction area is only 16cm diameter caused by small space on the mower
, a bit more than 6 inch…this cloggs after one hour with ash because of the small diameter…so i made around a part of bypass screen, in way that the gas can travel besides , when the area is blocked by ash…of course the nozzle must be high enough above to not make inefficient the reduction area…ithink your diameter over the grate is too small, when you must shake so often…
further, when your gasifier runs , than is good to fix the motor or gen-set on the frame , that causes vibrations what can help to avoid bridging…
5 Likes
Yes Giorgio, I have been coming to that conclusion too. I built the reduction according to a successful gasifier running an engine of my size. It’s weird though, the gasifier runs well on wood but not on charcoal.
Since I have decided to go charcoal, I think I will try Gary Gilmore’s simple fire. I have most of it built anyway already. I’m going to remove the reactor from the 55 gallon gas collection barrel and put a top on the barrel. I have a fuel inlet where the grate shaker is. All I have to do is seal up the ignition port. It’s a little on the large size - I would rather go with a taller and narrower propane tank, but this will at least get my feet wet.
5 Likes