Chuck. I think we must also consider that the air entering the gasifier represents only 50% of the volume of gas leaving. I hope to be understandable, correct me if I’m wrong
Thierry
From post 447 (also relevant to post 259), yes it literally says ‘air rate’, not gas rate.
And I was calculating gas rate…
The air reacts with the char and the products are roughly twice the original volume of the air.
I think you’re right… if you want to calculate the air rate through the nozzle you have to use another 50% in the formula.
Does the gas rate calculation look right to you?
The implication are not good for small engines.
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Would you happen too know of any good charco gasifier design books, with clear pictures, as like the ones you posted , i want too buy a book if one exist.
Hi Kevin, no, sorry, i don’t know any good books with charcoal gasifier design, all i got is from old books, 1920-1950s, mostly principle drawings. i don’t know if there has been much work on charcoal gasifiers since ww2, other than can be found here on this excellent forum?
The Swedish book “Gengas” (available in library here?) has some drawings and a little about dimensions, also FAO (?) report has some? If i remember correctly?
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The book labelled Driving On Wood aka the PEGASUS book has tons of old charcoal designs @kmrland that’s where I found the diagonal draft gasifier.
At the end of the book it shows a lot more designs.
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Kevin, you sound like me 6 months ago. The best info I could find was this thread:
Lots of designs from guys here on the forum. I read and studied all of them because I really wanted to run on charcoal. In the end, I decided to build the bottom end of @Wayne’s gasifier as it is the only one proven for the long haul on a big v8 engine. I can then have the option of switching to wood if I want in the future by adding the hopper ect. If I was going to put a gasifier in a small car I would probably do something similar to what @KristijanL did in his Mercedes.
Garry C
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Thanks for showing me too the peg gas book.I got too go back and look at the end of the book for the design pics,Thanks Man.
Thanks Garry Campbell for sharing all the char gas pictures, lots of good build ides get started.I can tell you are a high tech guy, getting all that info on char gasifiers all into a nice package, Thanks Now i gota go copy those picks and writings for reference too build a charco unit. That really helps.Thanks again.
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I will check out the sweedish gasifier book in library/Thanks
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please excuse me, I’m never completely sure of my calculations when I want to dimension a nozzle. I especially wanted to make sure that I use the formula correctly
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Are building a cross flow charco gasifier, or horizonal/ are they the same thing, and what the main advantage / GAIN, too useing the design,THANKS CODY E-T.?
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With the diagonal downwards flow, if you dimension it correctly, you can blend in some wood. It’s basically a super simple downdraft but it has to be sized correctly.
Otherwise it’s just like a cross draft. If you run a cross draft on only charcoal it’s fine but they don’t like tarry fuels like plain wood. A cross draft is also meant to have an ash dump on the bottom to get all the clinker and slag out, usually once per day of use. The grate in a cross draft is just to keep the fuel and slag from getting sucked through the piping and not really sift the ashes out.
A diagonal draft you just place the nozzle higher up than the grate, but you have to space it just right.
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If i build a down draft char gas maker- can i install a single nozzle up through the bottom of the unit, or is the nozzer come through the side of the unit.Do the gas come out below the grate, how far from the grate should the nozzle be, Or how big diameter pluming and nozzle for a 1.8 pontiac vibe, You think. THANKS
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I’d go with a Mako style charcoal gasifier. Air jacket and nozzles. I’m eventually going to make one for the 2011 GMC using a car rim as the air jacket. Pipe nozzles to thread in and replace.
The Mako S1 from the Gengas book says with 4 14mm nozzles it could power a 2 Liter to a 4 Liter engine, so I think with 3 of those nozzles, or 4 of some 1/2" steel pipe nozzle you’d be able to power the 1.8 on the Pontiac and have good heat to crack moisture in the charcoal. I think the area below the nozzles on the Mako S1 was 14" diameter by 14" deep to the grate. They didn’t even use that thick of a pipe for the hearth, I want to say it was 3mm thick or around that, almost 1/8".
You could basically build it like a WK burn tube with nozzle tips or like an Imbert without a restriction. Preheat is always good but isn’t as necessary for charcoal. Bumpa Gary and Bobmac are basically doing that.
Mako nozzles pointed a little bit downwards to keep slag from building up in front of them.
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THANKS much CODY i will check that out once i find the gengas book, I am not premium member Yet. THOUGH thats a lot of good info, or probley enough,Like you said,those replaceable screw in nozzles idea i like TOO. I was thinking about that as i was typing, why a wk burn tube set up should work, it burns pure charco now though only below the nozzles, should work with a little exra thick metal around the nozzle area of the burn tube,Or fire crete few inches above and below the nozzles. and some scew in nozzles, maybe small water drip.
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The nozzles will keep the worst of the heat away from the walls. I’d say if you wanted to go thick you could use 1/4" tube and use 2" long nozzles, I’d start with 4 1/2" pipe nozzles. Buy some plumbing couplers and cut them in half with a chop saw and then you’ve got your threads for the pipe nozzles. You’d think the cast iron couplers don’t weld in but I’ve used them a lot.
If you use moistened charcoal you won’t need water drip, it’ll keep the heat down.
You should still have a cooling rail condensate tank but it’ll mostly be just water with some soot in it.
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Thanks again CODY, I will check that gen gas unit , i am copying the notes you gave me, back too bed for know , or i won’t get my dakota finished, its taking shape though, well the gasifier end of it anyway, the cab corners need under coating and a little mig welding metal fab next,or no end in sight,Dang salt eats up older vehicles from michigan salt roads.THANKS AGAIN for all the tech notes. I could get building with that great information.
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hello kevin, here some copies from the swiss gengas book from tilman (search under Til )…
slag build up in charcoal gasifiers, different constructions
and crossdraft, where the problem comes up that the slags leads the heat too much to the shell of the gasifier , and so the protecting effect from coal around the hot area exists not more…and further creates disturbs with gas-flow…
therefore i like the design of eddy ramos (ramosedmundo) with his nozzle that enters from the bottom, so less possible heat stress for the nozzle i would say…
easy water drip installation, the water cannot flow the gasifier when forgotten to close the valve…
the slag build up makes the form of a crater and from my modest insight this protects the nozzle , further one can make some heat resistant stones around the nozzle for prevent nozzle contact with the really hot area…
what i would modyfie at this design: i would not make the gas outlet on the top of the gasifier, but in about maybee 30 cm over the nozzle to avoid too much coal dry out…but of course than is needed a additional cooler…
.in the swiss book is also claimed that high speed air flow must not be connected with cross-draft design…
English-Manual-V3-PDF.pdf (2.1 MB)
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Thanks giorgio, its not in english, though what are them black sock looking area near in inlet nozzles/ I see the exit pipe half way up the side of the charco drum, is that a good way too pull the gas out. Looks like a slotted pipe maybe on the exit plumming.
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Kevin the black splotches are to show where the reaction is flowing
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