They will break in, you want them tight for this reason.
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This is making me wonder if increasing my single nozzle size to 2" will be too big for the 4.3L. The Mako I’m working on is going to be about 10 1/2" nozzles but I’ve got welded in pipe couplers to reduce them if need be. Only one way to find out and that’s get it finished and test it!
I’m still amazed the 1" ID hexoloy nozzle ran the engine, even if it was just stationary with occasional revving.
I’ll try to get the body of the gasifier done this weekend and take some pictures, it’s another silly simple build, nozzle going in and a gas exit a bit lower. This time I’m using a 55 gallon drum body instead of the smaller drums, it’ll sit below the roof of the cab. The 55 gallon body will give me more distance across so I can afford to have it not as high up. I haven’t made a grate yet, I might just test it without one, with just a simple mesh guard around the exit pipe.
Not sure what all I would add to make the design more efficient, it’s almost too much of a blank slate to think of design improvements for my simple caveman brain. Matt’s rectangular form factor definitely lends itself to better reduction zone quality for sure.
Maybe a semi restriction halfway down between the grate and the single nozzle? Would aid in moisture cracking. I think this design is only a little less sensitive than an updraft in my opinion, without really fine tuning the nozzle size and distance to grate like the Pegasus book suggests.
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Just try it out and see what happens. Then work from there. K.I.S.S.
Bob
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this is definitely all Seat of My Pants type engineering for sure. I don’t exactly know the mathematics to design a charcoal gasifier, and even if I did I’m not good at math! I think I have dyscalculia sometimes, I look at a number with decimals larger than .00 and I go all cross-eyed.
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Cody, I wrote something on this topic here, well, to repeat it again, the ratio of hot zone sand to the cross section of the air intake opening is supposed to be 100:1, I mean the area, which for round elements is calculated by the formula π×r ×r (r= radius) 
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Using that math it seems I’m looking at a 1:120 size ratio with the 2" single nozzle.
Or is my math wrong, is it Area of the nozzle air divided by the area of the drum?
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Cody, are you building the gasifier using the upward process? Or down? Or a diagonal process? If you have a 22" diameter hot zone and a 2" air supply pipe, it would be good to supply air to several smaller openings, but I don’t think you need a wider area than 15".
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It is diagonal, downwards direction.
I’m just using a 55 gallon drum with a diameter of 22". When I used the other gasifier to test on the Sierra it used a 1" nozzle in an 18" diameter body.
The Mako body will be roughly what you just described, 10 .5" nozzles in a 15" diameter air jacket.
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Finally found my jumbo nozzle I made.
It’s very hefty, weighs maybe 1kg alone. Inside diameter is about 1.8" at the tightest point of the nozzle.
I have this new body made up and you might be asking, “Why is the gas exit a 90 degree fitting?”
Excellent question. I goobered up the hole alignment and I used the 90 degree to bring suction demand back to the centerline. Simple is as simple does I guess.
I doubt it will affect much. Or it will cause a thousand problems.
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Air comes in and goes down through the hot charcoal and gases go out the 90 degree elbow at the bottom. I do not see any problems with this. Except the gases are having to make one more extra turn before exploding in a IC Engine cylinder.
Bob
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I’m thinking since the gas exit is off center I might have room to use the corner of the bed for a cyclone or a drop box. Drop box would be the most beneficial because it will give the gas a room to be less turbulent before being cooled and filtered.
I am going for now with a vertical grate, just tacked in a couple places. The idea of this gasifier body is I can configure it how I want, and change parts easily. Simple nozzle not good enough? That’s fine, I’ll swap it for a Duck’s Foot Nozzle to give a spread.
Drop in semi restriction, drop in grate, etc.
I may go with some of my ceramic wool in a layer or two, and coat it with some of that IR Reflective refractory. Or a simple treatment of sodium silicate.
It wouldn’t be great for long trips, but for the 30 mile radius I travel in it’ll be just fine I think. Will still require updraft quality charcoal in this configuration.
If I want to return to a diagonal point I’ll look for a 2" 45° Street Elbow fitting.
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If you tack weld two U shaped channel pieces vertical on ether side of the exit tube you could slide a screen down into the channels and bend the top of the screen to fit the curve of the barrel this will give you a lot of surface area to keep from plugging up on your gas exit. Any fine ash will go through but the bigger pieces of char will stay in the barrel.
Yes a drop box after the exit pipe will help filter more ash out of the gases and cool the gases down.
Bob
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You could just do it with a piece of corragate roofing on the inside of the barrel with a smooth sheet of metal to hold it to the out side of the barrel. This barrier will keep the out side barrel cooler. It works great on the WK Gasifiers lower part of the gasifier. Fill the space between with ash. It does not have to go all the way to the top of the barrel. And this is very low cost effective. Compared to the others ways to insulate the barrel. Any hot spots on the thin barrels will burn the paint off and rust out like Wayne said.
This is how all my future barrel insulations will be done for now on. The ceramic wool and welding blanket works but it is not worth it in my opinion with the cost difference. The less cost in building these gasifiers the more cost effective in saving gas monies they become in long term driving.
Bob
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I think what I’m trying to achieve mostly with this gasifier as a test bed, is to find out what minimal things need to be done to make a good downdraft charcoal/blend wood gasifier.
I really hope this nozzle holds up. I think it will. I can definitely clean it without worrying of breaking it when scraping slag off.
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Waiting on a few plumbing pieces and some ceramic wool rigidizer.
The intake is going to use a 2" Tee fitting with a flapper valve mounted vertically for gravity to assist. My truck has a pretty aggressive rake angle when unloaded so I don’t trust a swinging check valve to stay closed when parked if it’s horizontal.
The other benefit of the check valve being vertical is the INTENSE light given off by the other nozzle tells me I should point it down. I really hope I don’t make a dang strobe light with this.
Regular 2" plug for lighting and cleaning the nozzle out.
I’m planning to adapt my old grate to fit in this gasifier, just with a sheet collar to take up the rest of the space. On top of that is ceramic insulation.
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I had enough junk angle iron laying around to make a grate. I also have beaucoups amounts of bolt lock rings.
Epitome of lazy, I almost didn’t want to take a picture. It’s diagonal somewhat because it’s resting on the exit fitting.
If it was a barrel in a barrel I could suspend the grate. A single barrel unit actually gives some challenges.
I should document it even if it’s a warning to other lazybones like me.
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Looking good Cody. Hope to see it running soon.
Bob
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Got the flapper valve and tee. They’re stainless, even the 2" close nipples. Surprisingly they’re cheaper than standard steel fittings on Amazon even if it’s only a few dollars.
Flapper valve was 26 dollars if you can believe that.
Here’s a rough idea that I intend to go through with after generally testing it.
In this super basic form factor I’ll call it the Benchmark phase.
My next modification will be to fill in the useless spots with ceramic wool hardened with sodium silicate “water glass” treatment. Making a trough for the active zone to stay in and hopefully allow me to blend in wood pieces or very wet charcoal. From there I can either bend down the nozzle at a 45 degree or keep it straight.
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Applied some red RTV in the seal channel, smoothed it over with a homemade putty knife aka an expired credit card.
Let that set for an hour and I have it banded down tight against the drum with cling wrap on the barrel.
None of my lever ring clamps are tight enough to hold it down and that bothers me. I guess I’ll need to use some toggle clamps to cinch it down tight. I don’t think springs will be enough. Waiting for my high temp grease to come in the mail before I do any testing. I’m excited to see how it performs in this most basic shape.
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So this will be the way to fill your hopper everytime. I would think 4 to 6 springs would hold it tight if you put the lid on the same way by marking it on the lid and barrel. With the big lid it will make it a easy access to get into the gasifier from the top for maintenance.
Bob
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