Because, as in a wood gasifier, the fixed burn zone, prefferebly with a restriction, gradualy “licks” away the chunk surfaces as they migrate down. Everything is more confined, concentrated. The goal in the end of it all is that the gases pass trugh pea sized charcoal before exiting the burn zone.
But with a updraft, its the other way around. Smaller bits are at the nozzle, biger ones are at the boundry of the burn zone. Thats a recepie for a forge, not a gasifier. Hope it makes sence
11 Likes
Hi Kristijan have you ever tried to impregnate the coal with a little waste oil to enrich the gas for a downdraft generator?
1 Like
Kristijan,I am looking, in the forum, where you posted photos and explanations of your downdraft coal generator
1 Like
Going to attempt an engine run. Hopefully my predator 212 can pull enough to keep it running. I stuffed some open cell foam in a 2" pvc pipe to keep as much soot as possible from ruining the engine but if it dies, it dies.
1 Like
Can’t wait to hear how she runs. Depending how hard you “stuffed” it, 2" may be too small to allow unrestricted flow? My first small engine gasifier filter, based on Gary G’s example, was a 4 inch block of open cell foam cut round so that it slid snuggly into 4" pvc. There are many great filter options, if your 2" pvc is too tight.
1 Like
Trigaux,
Here is where the development of Kristijan’s downdraft charcoal gasifier begins: Mercedes-Benz E230 vol. 2, charcoal powered - #365 by KristijanL
3 Likes
Yeah I’m not sure if it’s the engine or the filter. It can’t get enough force to run. Going to try one last time but without a filter. It’ll just be a short run anyhow.
Edit: I give up on this little engine. I’m having way too many variables screwing with me and I hate relying on the rope start.
Next engine test I’ll have built an actual filter and I’ll test with the Sierra. At least I know that will pull correctly.
How about drill for starting?
2 Likes
That would have been nice but in the heat of the moment I wouldn’t be able to find the right socket. My biggest problem is for air adjustment I just have a humongous 2" ball valve that didn’t want to comply. I don’t have any reducers to use a reasonable sized valve. It also didn’t want to start on gasoline but it has been used and abused so I’m not surprised. Engine was rescued from a mini bike that was left in the elements for God knows how long.
Also the state of my shop would make a crazy person look sane.
Also also not a fan of the lack of things to cap off the flutes with. When I shut down I get gentle flames exiting the flutes and I’m afraid of burning up my charcoal in the hopper.
I think I’m going to see about using what I’m learning here and trying to adapt a Svedlund system.
Taking a downward nozzle like the Svedlund but welding a heavy cap on the end, and drilling holes 90° from the end to make an outward ring of nozzle holes. These would be pointed at a ceramic wool burn tube for insulation sake, and a little below that a restriction of more ceramic wool at a smaller diameter. I’ll try to draw it up on my sketch paper.
1 Like
Now that I’m thinking about it you wouldn’t really need a lighting port. Could just light it up like Wayne does with his WKs. Could install one with a sight glass like Don does though.
Exit gas wouldn’t really even need a grate. Matt Ryder has shown you just need a cover as your grate in his ammo box build. Or you could use expanded sheet metal wrapped in a tube or hardware cloth in a 1/8" size. Not sure what size holes you would want for the nozzles or how many of them.
The reason why I drew it with a welded capped bottom is to prevent a blast of air cratering directly beneath the nozzle causing overheating. Svedlunds got around this by using kanthal. The added benefit of the welded cap is when you run a drip feed the water lands on that cap and lets the water boil off to be sucked out through the nozzle holes.
I plan to build a tester of this and see how good or bad it does. I intend to use a 1.5" pipe with a 1.25" pipe pressed into it to double the thickness. Or if I’m lucky find a 1.5" steam pipe or the like at the scrapyard. The welded on cap will be at least 1/4" thick.
1 Like
Tinfoil is always worth a try. I have made all manner of caps and plugs and gaskets out of a few layers of it crumpled up.
4 Likes
yep i used tin foil and even plastic shrink wrap over the years to stop the air getting in .
Cody , i can sense the frustration of not having the right bits and pieces around , but i bet you will find most things will fall in your lap as each day goes by , just keep your eyes open for the right kinda junk , starting with an old lawn mower and a cordless drill with a loose fitting socket and old water pipe fittings , they were always on my radar in the early days .
Dave
6 Likes
Thierry, l think l have done this but cant remember for sure… Shuld be no problem thugh.
Yeah thats gonna be hard with a 2" valve… For refference. On my Mercedes l had a 1/2" opening for the air inlet and it was spot on perfect as air adjustment goes. For a long time l didnt even have a air adjusting cable in the cabin! I just drove on this pre adjusted setting untill l got a lean condition, that was couple of days… This ment its time for ash cleanout.
Charcoal gasifiers make incredibly stable gas!
Anyway, what l like to say, do t go crazy with the air inlet valve size even on your trucks. Smaller valve will give you more accuracy.
On your Svedlund try, l think the idea of the capped end with water is good, but if you go this way you will not be runing for long instead of investing in a tungsten or something like that nozzle like Dave has. Even kenthal cant last forever.
Althugh water might cool the nozzle enaugh while operating, there is a huge amount of energy stored in the glow zone at shutdown. And with no water and air comeing in to cool it…
Also, l wuld extend a thin water pipe in the air pipe right to the cup. This will deliver water right in the cup without aerosoling it on the way so that it all can aid to cooling.
3 Likes
So you’re saying to get a thread on tungsten nozzle tip? Would the tungsten survive in the shut-down glow zone?
Also I think I already know the answer to this question but how would Titanium grade 5 hold up in this zone? I think it would have the same issues as Stainless Steel.
My idea is to use thick steel to get a lot of mass to protect itself, just like with horizontal flutes. I think I’m going to build a small scale version for testing using 1" with 3/4" pipe pressed into it. I also will be using pipe fittings so it can be disassembled for replacement or repairs.
You realy need Daves opinion on this. He is the one that has good sucsess with his tungsten nozzles.
As for mass, sure, mass is good. But remember, no amount of mass will survive the temperatures unless the heat has something to go. With mass we usualy achive fast enaugh heat conduction away from where it is not wanted. Some like to do that by venting it away, and @Handy_Andy prooved the concept with his aluminium nozzle, and it works. But l like to squeeze everey drop of energy out of a gasifier and am a fan of internal heat circulation (intake air used as a coolant). Same as our host Mr. Wayne
5 Likes
I wonder how the Svedlunds and Gragas systems lasted so long. The kanthal only went but so far on those. I guess their benefit was replaceability of parts.
1 Like
If I do an oil change away from home I just dump the waste oil in the hopper and usually throw the filter in there as well.
6 Likes
As soon as I get enough loose money together I’m going to buy a mig welder from a coworker. Then I can try my hand at welding thinner stuff more cleanly. I have a few things laying around that I could build a heat exchanging hearth like a WK that could work for charcoal. Air compressor tank that is slightly smaller diameter than a 20lb propane tank, could split the propane tank on the old weld seam and then fit it over the compressor tank after welding my just freshly replaced metal cutting bandsaw blade onto the burn tube for heat sinking.
Then I could base a Mako design off of that.
2 Likes
I have a 1.5" gate valve that I’m going to use for metering air for testing. I just need to clean up the area in front of my shop and I’ll try to use my Cherokee Laredo as a test bed. I can pull the ballast resistor to cut off gasoline flow once I detect the revs increasing and try to get a good lean idling condition. It will be a stationary test but since the Jeep has a 4 Litre engine it’ll be close enough to the demand of the Sierra. I can monitor temps and see how it performs with minimal water drip. The PVC fittings I have put together are just slip fit with no glue so if I have a puffback it will just pop off right there.
2 Likes