Cody you say that you overestimated the flow of the 4.3 your truck engine size ? and because of that your nozzle is a little too far away ? i don’t really follow as the larger the engine the further away i would have thought to allow some cooling of the gasses .
you also say With Crossdraft types that distance is very key. is that written somewhere so i can look ?
The reasons for my questions will come clear once i have smoothed out a few minor problems on one of the downdraft builds i made so i am trying to fins as much info as i can right now .
Dave
@d100f In the Drive On Wood book in the Library, aka the Pegasus book. With a Cross Draft you want the glow zone halfway to the grate, to prevent dirty gases from slipping past. I think I have a screenshot saved somewhere.
The thing about a Diagonal Draft is it allows the distillation zone to make more of a protective blanket. So I think adding somewhat of a restriction would help.
You could achieve similar with a Cross Draft by making the grate narrow. Maybe solid plate on either side and above and below, with a choice spot for the gas to flow through.
One of the Brazilian guys has done that somewhat by welding in a large pipe as his gas exit, tunneling the gas.
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Well i have a open grate similar to what you have on your unit , but i have a restriction on it allowing gas to travel a little further along and i have come up against a few issue’s that can be fixed but a Pegasus cross /downdraft has a heat issue , both the drum and the gas have unacceptable heat levels that are not suited to my stationary units , now it may be because of me and due to the fact that my inlet nozzle is only around half inch , and running a 400cc engined generator on full throttle and full power on very dry charcoal , and as yet no water drip has been added , that will happen in an hour or two when i go out to play in a while .
One other thing i am noticing is that i am getting great gas from the start , my large generator has no problem in giving my inverter charger as much power as it wants , now that is strange as normally i would have to wait at least 10 mins to get up to 60 amps charger puts into the pack ,
Still plenty to play with and change and experiment with before i am happy to make a finished unit for myself .
Dave
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For reference to nozzle size, I’m using a 1" ID but the tip is slightly more narrow than the piping running to the nozzle. I think you might see it running cooler with a 3/4" nozzle tip with 1" delivering the air.
Even with my nozzle protruding over 7" into the fuel, it gets hot as the dickens, but not above the nozzle area and not near the gas exit.
What’s the size of the restriction? I’m thinking of making my restriction half the diameter of the barrel, so it would be about 10" in my case.
Have you thought about adding vibration from the engine to rattle the gasifier and help fuel flow smoothly?
Also, my charcoal got fairly moistened when I added some of the really big store brand hardwood lump charcoal to keep my smaller stuff from falling through the grate. After my bag filter I did get some condensation in the PVC routing, maybe a few CCs of it. In all fairness to that I didn’t have a lot of cooling rail and I wasn’t moving. Or maybe the condensation dropped out because of a change in pressure and all the bends in my piping. I’d maybe consider a drop box, then the cooling rail and then the filter also doubling as any sort of condensation collector. Or add a trap for the water to fall into before it goes to the engine.
OK Cody I have added a water drip now its started up fairly fast again under 1 min and engine running under 2 mins , i must be sucking air in through the gas reheat pipes behind my engine before the final filter as i have the air valve nearly closed , will look at that some other time as i can work around that for now .
Great power again from the gas and full power at the inverter engine has no problem keeping up with demand so far .
The gasifier drum has a outlet pipe more or less on the bottom of the drum , and the nozzle is set half way up the drum , leaving 11 inches of charcoal above the nozzle .
Update just went out side to measure the drum and the temps were crazy hot and so have stopped it for a while so i can open up and see the charcoal level before making adjustments and restarting .
Temp on the top of the 22 inchx15 barrel are 105 C on the lid 320 c at the nozzle plain and lowering too around 140 C at the bottom of the drum pipe work too the first filter was around 120 C gas temp is unknown at the moment but i would imagine its in the region or around 80 C
My Restriction size is changing all the time , but i do plan to try and set it at around 7 inches as i have a very nice grate that will fit good .
Will see what it looks like inside in 30 mins once cooled down a bit
Dave
Run time in total was 40 mins
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You’re pointing the nozzle down towards the gas exit, right? I set mine up so I could use plumbing elbows, and a 45 degree had me pointing right at the exit pipe. I think next one I make, I’ll weld the coupler in at the angle, so I can change out nozzles from the outside like how Matt has been doing.
I wonder if it might help to add a 1" layer of some ceramic wool soaked in water glass to harden it? If you did that you could probably get away with some wood blending since the insulation will help cook anything down.
Next run you attempt, try dampening the charcoal a little bit, 10% by weight maybe. Maybe that’s why I’m not getting as hot it’s cooling the whole reaction down.
No i am not pointing it down towards the exit , if anything i want it as far away from the exit as i can get , if i have to make a maze for the gas to travel though to slow it down then that’s what i shall do , one of my test runs did have a 90deg elbow but that was worse ran way way too hot , i am pulling some gas through this system for sure , this is only a experimental while i am getting my stainless system together , i rather cut this one around than the nice shiny one .
If i have to install insulation to this then i will make a jacket to go around the outside as i do not want to make the inside any smaller than it already is .
Wetting the charcoal from what others have said seems like it might be the only way to run a small system without the high temps , we shall see .
Dave
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Oh by the way Dave I forgot to mention, the final resting place for the Diagonal Draft is going to be on my friends Jeep Cherokee Laredo. Has the 4.0 I6 engine. He’s probably one of my only friends as daft as me to put it on a vehicle he owns. Everyone else has seen my results but don’t want anything to do with it personally.
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That will be 1 more modern jeep that will be gasified and DOW going down the road. Good for him.
Bob
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Status update from the test trial of the diagonal draft.
@d100f here’s what my hexoloy nozzle looks like. Lots of slag congealed right on the end, even just inside. I’m wondering if it’s liquifying the silicon carbide.
It formed an almost perfect donut shape inside the nozzle tip, restricting it slightly.
Definitely too much velocity, after chipping some away it looks like a slight amount of the hexoloy flaked away too.
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The diagonal draft tempts me.
I’m going to try this hunk of steel I called a nozzle but is really more of an Air Cannon.
I wonder if restricting air at first with 1.25", and then letting it pour out of the 2" nozzle will hurt or help anything. I’d rather not cut out the 1.25" coupler I welded in.
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Cody , the Hexoloy you just showed in the photo’s has run how many hours let me guess its run about maybe 2 hours at the most just making a flare ?
If you think that’s bad wait till you see a photo of a carbide nozzle i am using in the downdraft i am running at present , so far its run around 36 hours and it looks bloody terrible ! But underneath all the crap its still fully intact .
The first Hexoloy nozzle i still have from 2018 in my 55 gallon updraft , its mounted vertically from the bottom and so works just like the flute where you get a build up of slag and clickets on top helping to protect it , its seen better days after 4 years of a lotta lotta hours many hundreds of hours for sure .
Dave
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It ran maybe 10 minutes of flaring and 2 hours of idle engine load with intermittent rpm increases by me blipping the throttle.
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Oh so you did manage to put your cross / downdraft onto the Mazda sorry i don’t remember reading about it , so how did it go ? what was the gas and pipe temps after 2 hours running ?
Dave
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That was in the Sierra.
When I had just the fuel pump cut off and the injectors on, because I put a fuse tap on the wrong fuse, it was running fine at idle and responded well to throttle.
So, definitely undersized for that engine just based on how the nozzle was reacting. 
Pipe temps, for the 20 some odd feet of cooling rail it was cool enough I could leave my hand on it. But the gas exit was maybe a 4 second touch level of hot.
But I was getting clear water throughout the PVC, maybe a half cup or less but enough to realize it would be an issue for extended drives.
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Ok my mistake you have that many things on the go its hard to keep track the way you jump from one to the other , oh to be young again !
Well i am slowly sorting out this barrel downdraft its a long learning curve and it does throw up a lot of different running conditions every time i run it , yesterday i took it all over to the yard and tried running a 6 cylinder old Bedford truck and a 4 cylinder fork lift , gasifier started both but would only run idle little too no throttle due to the small size of the nozzle you could hear the drum compress being sucked in with a half inch nozzle wayyyy too small .
Dave
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I have a kind of chaotic work process.
Basically when I get frustrated with something I’ll stop working on it, or else I’ll goober it up. Little here, little there.
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That how I do it too. It works for me. Step back and figure it out and work on something else. Wait for free parts to come to you or find. But some things you just have to buy if you can not find it.
Bob
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There are acknowledged Miracles. Jesus walking on water and raising the dead. Noah figuring out what to do with tons of animal poop on a boat and me ever finishing all the projects I have partially completed. I hope that when I’m dead I can finally stop starting new ones or thinking about reworking the old ones.
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Hi Dave, on the down draft gasifiers with 8 or more nozzles in a ring formation in the WK style firetube. The preheating of the air helps with the longer run times. This due to not having to have blasting of air through the nozzles. Even though I have larger nozzle holes designed for a larger engine, the same unit will run a smaller engine just fine. Now this is with a wood chunks gasifier.
This is why I am making a charcoal type gasifier with some of the WK design built in to pre heat the incoming air but more important reason is to protect from some of the heat from the fire tube wall. This is what the added heat shields do. On the out side of the firetube is where the big secret is that I will not talk about on this side of the site.
The lazy air coming into the firetube moves down to the restriction opening and this is where the tuning on the gasifier is done by size opening and distance of the restriction opening to the nozzle. Above and Below the opening is the reduction and charcoal reserver that is very important all the way to the grate.
If you just keep working with the down draft style gasifier you will find the right size and tuning.
Water drip or moisture in the charcoal is a must to bring the Hydrogen levels up to match the power of a wood gasifier out put.
Loving both sides of the Wood or Charcoal Gasification.
They both made burnable gas.
Bob
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