It might compress a little but the vibration is more than likely going reduce the fuel bridging issues.
I am not familiar with Joni’s design.
Chips are a real difficult thing in small machines, big machines also have bridging issues with them.
Small blocks however under 1 inch seem to flow nicely in everything.
Bigger machines might work better with bigger blocks however.
it all depends on the hearth size and air velocity to find the best size blocks.
I have easy access to softwood chips.
Its my opinion they do not gassify well…
Looking at my hopper on my Mini Joni, I might remove that and replace it with my old steel milk can. Can’t think of any time I’ll need more than 10 gallons of hopper in one go. Save the big 25 gallon hopper I made for a different build.
I didn’t follow Joni in every detail. I made a grate out of angle, so ash fills little troughs and protects the metal from very high temperatures somewhat. I drilled the holes for the bolts that hold it in place 1/8" oversize so it can rattle just a little. Here’s a top view that I used to lay it out.
Now I’m making hopper tubes and a tar still. The still will drip the tar into the reaction zone. I’m hoping that removing water will allow me to run a 275 cc engine generator that I have without resorting to charcoal.
Did you make an inverted V ash cone to make your reduction zone? I just used some 6" pipe and welded 2 small bearing races for my restriction to build some ash.
I still need to add a cooler and filter to mine before I fully test it. Might add 3 circumferential nozzles in a much much smaller nozzle tip size since I used a 12" propane tank for my gasifier body, and keep the central nozzle to prevent a cold spot in the center.
Mine is scaled up ever so slightly but I hope I can run a 400cc engine.
Well, there you go Rindert . . . a single central air nozzle! An instant fail in a small raw wood gasifier.
You and Cody keep referring to Joni’s recommended system??
I’ve read his own built shown systems. Not a one uses a single central air nozzle. JG7, JG8, JG9, JG10. All with peripheral air jets.
The closest he got to recommending a single air-in was the system with a drop down single fed internal nozzle ring.
Single central air’s have been claimed to work on raw woods: The Australian Kurt Johanson (sp) and a couple of others guys. But only on bigger than 275cc, high flow drawing multi-cylinder engines.
Convert what you have to the drop down at least five jets internal peripheral air ring.
You want the oxidization heats sources out near the outer; will be colder, edges. The made wood volatiles mists and gasses then will not be outer walls cooled, but force thru the center hot hell lobe.
O.K. Yeah.
And how is this in any way related to Joni’s shown video except having that single central air nozzle??
Point 1) he shows in the diagram and video a tall narrow in proportioned tube gasifier.
Rindert you have made a larger diameter; larger volume hopper gasifier. Making for a larger volume wood cooker chamber.
Point 2) look at the heat rust on his outer tube housing. That smaller diameter surface gets HOT, HOT able to hot char convert wood volatiles. You will never be able to generate this outer heat only pulled by a 275cc engine, Rindert. Certainly not generate the heat energy to convert your much larger volume of raw wood volitals cooked out.
Point 3) He said wood chipped gasifier. Wood chips always have a greater internal resistance flow than a wood chunked fed gasifier. In his tall skinny gasifer this slows down the internal volatiles flow for a longer residence time in heat exposure. Wood chunks allowing fast flow of the unconverted upper system volatiles.
Fellows. Details matters.
So not a Joni at all. His shown pathway was not followed.
A Rindert in development.
Steve unruh
Anyhoo, The way I see it first you make a burning charcoal hell, then you feed air, tar and maybe a little water thru it, while keeping the char at a temp where it can do it’s work. I was watching this it with one of those non contact, pistol grip thermometer. the shell outside the reaction zone seemed to run ~350F. To me that says there is a lot of potential to save thermal energy by insulating.
Of course when I over pulled it the whole lower part, ash door, gas outlet nozzle and everything got up to 800-825F. Don’t tell my wife. LOL So now I have some notion of what actually happens when you over pull.
At a gut level, you don’t learn without doing.
Rindert
That was the original idea. But in the real world I haven’t figured out how to make a cone shaped hole in silicon carbide. So this is what I could actually do.
Rindert
The grinding wheel restriction is crumbling. This isn’t the same material foundry crucibles are made of. Maybe just the binder that holds the silicone carbide grit together isn’t able to stand up to the temperatures found in gasifiers.
Rindert
Rindert I would maybe look for an old golf cart wheel. You can use it as a combination restriction and reduction, the center hole is usually 3" but you could always put a plate over it.
Hmmm, What is it made of?
I would think something with large thermal mass, high melting point and high corrosion resistance. I think I’ll try furnace refractory next. A tungsten carbide nozzle was reported on this site and apparently worked. I’m going to keep the grinding wheel in there for now, and make a tar and water still.
Rindert
They’re made of sheet steel, looks like 14ga or maybe 12ga. I would put it in to build up ash. They’re about 8" at the bead seat and 6" in the center, I had thought about using one in a 9" diameter tube.
I did not want to be a party pooper but I kind of that that was going to happen.
The binder is designed to be flexable and allow some stretch and shock resistence.
Its probably something with a rubbery quality to it that melts.
But it could have gone the other way…
Somethings you would never expect like never seize will become super glue when heated beyond what they were designed to do.
It could have gone one way or the other.
Might turn out there are some good binders out there that don’t; degrade but cook down to super glow too…
Right. Morgan makes silicone carbide foundry crucibles. Sometimes when you get one that has too much glaze on the outside it will run down and stick the crucible to the stool. Makes an orange hot gooey mess you don’t want to deal with. Others make SiC thermocouple sheaths. I think if one were to cut the end off one of them it would make a good nozzle. I just have to find the right shape in a high temp application. The right Leggo…
Rindert
You never know unless you try Rindert. For a stationary system where a little extra weight is not a problem I think refractory is a good material. I used it as the base for my reactor in my first unit and it has held up fine. I would be good if you could find a way to reinforce your present restriction to see what could be done with that kind of material.
Some of us have been using these for nozzles Kent. The will slide tight into an inch and a half sch 40 coupling. Aussie Dave has been using the same nozzle for years without any problems.
If you can’t find anything ideal for a restriction I can always search for some of my spare bearing races. Weld them together, very high quality steel and fairly thick.
