So is it a singular central nozzle acting like a showerhead, or is there a perimeter of nozzles in the wall as well?
Would be really interesting to figure out nozzle ID to a ballpark displacement. I guess use Imbert nozzle dimensions but combined total area of those to imagine a singular?
Nope different process. My guess is 3/4 to 1 inch pr 1 lite of displacement. Charcoal is much more tolerant as well wit a huge turndown ratio. This is where building a team I think would benefit a vehicle. Build a box not a cylinder that will make better use of the square bed box.
You guys want to something cool put a small engine carb on your intake take jet and use that for your water flow. It will need to be linked to your accelerator. Mash down the go peddle it adds more water to boost your water intake. That would be cool.
I think you are making it too complicated just use a side nozzle. Shield that nozzle and keep it wet you will not have any issues if you do this. Dont let it go dry of water.
Bridging above the nozzle.
Iâm not sure of nozzle size yet. The idea is just a showerhead style nozzle.
I have always been concerned about bridging above the nozzle but in all the test runs it never has, even sitting still.
I am hoping for this to be a wood gasifier i think it will work.
Do you guys think i need a restriction or a grate? @Matt @Dualfuel @KristijanL
Restriction or reduction? Wouldnât you want a restriction/choke-plate for raw wood? Joni has done fine without a reduction though.
Jakob,
Earlier posts said this design made good gas. It was just wet.
A restriction is to force the heat lobes to pass through the center band of incandescent charcoal. Seeing as the center tuyere is already doing that, I would try it with no reduction tube or restriction.
My assumption is that from the tuyere out to the hopper wall will be a heat gradiant. Hottest at the tuyere and coolest at the wall. I think the trick is keeping it hot enough somewhere below the tuyere and by the wall, that the wood gets cooked to charcoal.
If the gas always passes through hot carbonâŚthen the CO2 will always get reduced to CO.
Is the output really wet? I have trouble with that, seeing as you have kiln dried maple. It should burn hot enough to reduce water. You should not have a big moisture load being sent through the reaction. So where is the steam passing by the carbon? Or is it an air leak down below somewhere?
Anyhow, itâs the best kind of fun, working on a new reactor.
I want to redesign it so it doesnât have the double wall hopper and just use a standard WK hopper. I think that will held a lot with moisture. Also some cooling systems will help a lot.
That is what is making me wonder if I need a reduction zone because Moisture/ tar could be slipping through. No leaks that i know of in the one prototype that we used the most.
Oh I was thinking this was for a charcoal gasifier. The light weight / simple through me way off. lol.
Ok your center tier design is a good idea then for direct fuel system and Ive always thought this made better sense. I donât think bridging will be an issue and having that jet in the center will push and direct heat from the center of the raw fuel above so it can not fuse and bind. This actually will solve bridging problems. For the jet, just use a single straight jet. Focus that heat to the center at (high velocity) as much as you can and using a single jet is the only way to do that. It will form insulation naturally around your oxidation zone. I think you should try it without a restriction fist but may need an (hour glass shaped hearth) and your grate should have a solid center this will prevent center channeling. I can see that coming without this. So to visualize you gas flows; Primary air comes out from a single point at your jet and then fans out like a cone and then to the grate. Adding the center core to the grate ensures this happens. On the outside of this flow cone natural and regenerating char insulation will form.
Yes you need a grate with a chamber under to equalize the pressure. Otherwise pulling out the side will make the unit lopsided and the gas flow will be to the one side where you are pulling out instead of evenly from jet center to grate center.
What you will have is a Central Nozzle High Velocity Down Draft Gasifier.
Hello Jakob, donât be offended if I express my opinion in your topic.
I was also thinking about the center nozzle from the top down, but I decided to make the air supply from the bottom up, because that way the temperature of fresh air and exhaust gas is exchanged more, the air is preheated and the gas cools down. The second reason is that there is no obstacle in the upper part. Sealing through the bottom is easily solvable, easily also with ART.821 SPOJKA, PREFABRIKAT â Livarna Titan. For easy construction, I would use a brake drum as a fire hose side-sealed and insulated with ash, and for air supply a thick-walled hose with side bores and closed at the top, which also allows the hot zone to rise and fall.
I would suggest silicon carbide for nozzle material. Foundry crucibles are commonly made of it. These thermocouple sheaths would seem to a convenient shape.
Also @d100f Dave & Brian seemed to get good results with tungsten carbide
Rindert
Some questions Jacob, I also think about making a new gasifier.
How long does an oil barrels suffice without breaking, like a jumper and protection around fire tube?
Donât you cool down the area of the reduction with the air to the nozzles?
I had problems with hanging the wood when I had the little fire tube, wonder if you not got problems with it, with the construction of the nozzle?
Hi Jan, the 92 Dakota truck from the book was built in 2012 by Wayne, my low barrel and hopper barrel are still being used. The middle section and plate is original only the firetube was replaced some part are still being used. Even the ash boxes are original. The doors were replaced because of the seals cook out. Thatâs 9 years and still counting.
Bob
Thank you for the answer Bob, I thought they were in for thin sheet metal.
@Tone Sorry for the late response. i have done that on my prototypes the problem is that it is supper heating the pipes and they are getting very badly corroded. On the bottom all i ever did was weld a threaded fitting in the floor then just threaded the stand pipe in to that. the main hot spot was where the pipe went through he grate.
@Jan With the prototypes I have the barrel was getting to hot with the nozzle blowing strait out i am hoping that with the nozzles pointing down and out that it wonât over heat. Honestly in donât know how long a barrel would last. On WK gasifiers they are almost all very well insulated so they last a while. most of what i have replaced on dads truck has been due to rusting away from the outside not getting burnt away from the inside. Make no mistake the heat causes them to be very susceptible to rusting.
I have not had any problems with bridg8ing in the hopper. I am a little surprised at that fact
@r_wesseling I have been thinking about that for the nozzles i am probably going to try stainless because that is cheap for me. If it doesnât work then i will look for something else.
Nozzle design?
Matt suggested a single nozzle pointed strait down in the middle. I have been imagining a shower head style nozzle. About 10- 15 small holes basically thinking of a flute nozzle where the flute is a ring shape.
Restriction?
@Matt If i am understanding you right you are saying to build a cone shaped reduction zone. How small would you make the small end of the cone or is that going to be determined by engine size?
@KristijanL I am curious about you opinion on all this?
No that is how flows will look inside
No this is a wood gasifier, this design wont have the velocity you want. When you get a fire going how do you stoke it up? You blow focused air into the ambers right? Use a single nozzle with high velocity. The fuel istelf will spread the flows up and it will fan out into a cone shape. If you put the core air block off at the center of your grate it will ensure this happens. The dynamics of this I see working much MUCH differently than an Imbert and I dont believe a restriction will be required. `
Dang it Jacob, now i cant stop thinking about this thing. I have this stupid air compressor that blew up and now Im going to have to build this out of it. lol
An alternate version would be to couple two propane tanks together using a pipe to create a restriction between the two. Id probably go with a 3 or 4 inch pipe about 2 to 4 inches long. Then once they are welded together fill this section between the two (on the outside) with refractory. Could use aluminum flashing to mold it or stitch weld a shell around this area.
This stupid simple approach is intriguing, and its hard for us complex wood gas folks to keep it simple. But I see just a straight pipe leading down the oxidation zone, this restriction and then a grate. The air feed tube just sticks out the hopper lid. To seal it use a section cut out of a rubber innertube and seal it to the lid with a flange and then a hole just smaller than the air feed tube.
Matt
I believe that in one paragraph you just described my next attempt at a small engine charcoal gasifier.
Something to run a 5kva generator.
2 questions.
How far below the 3â connector to a hanging grate
How far above the connector is the nozzle.
Yeah I think this design could work as both a charcoal or direct unit. One of the reasons I want to try it. I think 10 inches for the grate and a min of 6 inches above the junction.
