Hi Bruce as soon as i get a chance i will strip it down and show you , it is more or less as Brians sketch shows i cut the disk pretty close to the diameter of the drum so there were very little gap all around and just wet some ash all the way around not really more then a bead to fill the gap but it seemed to hold up as long as you don’t move or rock the drum too much .
Brian because i started out like you with holes on opposite sides all i did was screw a pipe nipple in that then took it all the way over to the other side of the drum ,just trying to extend the length of time the gas remains inside is what helped me .
Dave
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Hi BrianM.
I am totally NOT impressed with his downdraft system.
His explanation is grossly flawed. He talks about pyrolysis. Completely misses the internal making first hot CO2 and super heated steam H2O. Then that getting thermal chemically REDUCED into his stated actually engine capable H2; CO; CH4 fuel gasses. And the char carbons should be used up to contribute the extra needed C to turn the two O’s in CO2 into two CO’s.
He also regurgitates the false trail that any bio-mass carbonateuos input can be made to work.
HA! Only in University Labs. In big industrial highly controlled expensive fluidized driven, recirculating media bed systems.
I know personally fellows who have broken their hearts on wheat and oats chaffs. Broken hearts on sugar cane squeezes-out stalks. Too high of plants made silica in these; melting and flows clogging. Broken hearts on actual corn kernels. Heated; the starches and oils ooze out and glue into a sticky lump mass. Dried corn cobs have too light of weight of mass with lots of hanging up edge fingers not wanting to flow downwards. Broken hearts on tree barks. Far too high of mineral ash content. Flows internal gasses flows clogging.
Broken hearts trying to gasify ground up books. Gasify waste paper stocks.
Actually fuel wood pellets can be done O.K. in a dedicated for fuel wood pellets system.
Why? Why pay more for the end result electricity made than if you were buying pump gasoline, diesel or bottled propane?? Why.
Wood. Wood. Wood. Woods have the porous grain structures to do gasses exchanging. Wood is releitivly low ashing. True woods; does it easier, and better, for DIY, simple made systems.
He only marginally gets away with his pyrolysis fuel gas because he is using an old style valve-in-block engine. When the intake valve gets stuck up open on tars made, and passed through unconverted, and it is just drop the carburetor-intake. Pull the easy off cylinder head and spray clean free; manually moving back and forth the stuck valve.
Modern overhead valves engines, much more combustion efficient, and it is bending the push rods. Maybe bending a valve stem; the stuck down open valve head impacted by a rising piston. Maybe breaking the rocker arm cast stand. Or threads pulling, bending, breaking the rocker arm pivot bolt.
His whole attempt deserves a big Thumbs-Down as leading folks astray.
On his video that I put up for a look-see: it was 100% about thinking about using a paint pot converted to a cross draft system. The paint pot system has all of the elements for an easy build. For small engines. For a portable pre-made WOOD-charcoal fueled crossdraft system.
Regards
Steve Unruh
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I hate to do this since I’m close to having some kind of gasifier but:
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This isn’t the DOWN DRAFT that I originally wanted.
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My pipes and their locations aren’t in the best locations.
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I already have a working gasifier.
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I keep looking at that tank and imagining it as a small forge.
Today I welded up all the extra holes that I had drilled as nozzle locations, welded the bottom threaded hole closed, and welded in a 1" to 3/4" adapter which I now realize should have been a 1" coupler that that adapter would have screwed into.
I wasted at least all the charcoal I made yesterday and did get a flare from either direction but my lid is still leaking. The stove rope is out for delivery and should be here today but I’d rather save that and turn this into a forge. All my “wasted” charcoal is no longer usable as engine fuel because it has all kinds of raw wood, wood chips, and even ashes and dirt mixed with it but I think it could still work as forge fuel.
I still hope to build a down draft gasifier but I’ll have to do a lot more studying and find the right junk.
Not really wood gas related but a good use for extra charcoal or bad charcoal, raw wood, or I’m sure coal.
No use for the bent rebar. Just wanted to see if it would get hot enough.
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Brian, This topic, including your forge, was a nice ride. Thanks for sharing. It will continue giving encouragement and guidance to others considering a down-drafter. This topic woke me up this morning with a downdraft design from my junk pile: 100 lb propane tank, A 5 feet section of 1-1/4 inch finned steam radiator pipe for under tractor cooler, 8 inch diameter cast iron disc for lid, 4 inch nipple and cap for clean-out, schedule 80 pipe for flute tuyere, 1-1/4 pipe for bottom “grate,” and ammo can for filter. Two days ago a free 1970s Simplicity hydrostatic garden tractor followed me home. The engine cowling was packed with a mouse nest and it had one flat tire. A little B.G., Engine Performance Restore in the spark plug hole loosened the valves and rings enough to get her running. Now to gasify.
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Bruce, you can either take over this thread or at least post a link to your own thread on your down draft gasifier here if/when you start on it.
I haven’t given up on this but that first propane tank was going to need too many modifications and I wanted a forge. I do still want to make a down draft gasifier.
How big of engine is the Simplicity? I had one of those at one time but never got it running and ended up just scrapping it.
I did work on a 1960 Speedex a little while ago and considered trying to run it on wood. I think it’s a 10 HP but might only be 9.
This one had a mouse nest and a bees nest in it.
I can’t locate current pictures of that little tractor but I put new front tires on it and replaced the back ones with pickup truck tires. All the tires on it were bad. I put a new carb on it and throttle cable and got it usable but not “restored”.
EDIT:
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Brian, Mine is 18 HP. Thanks for inviting me to take over this thread, but it will probably a long time before I make any progress. Now that I know the engine runs and I have a gasifier plan, it is full stop so I can get our house and cars ready for winter. I look forward to seeing your progress when you get back to building another down-draft. Perhaps you have inspired others to keep this topic going while you regroup?
Grace and peace,
Bruce
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Are you sure about that Bruce? Looks identical to the 14 hp motor I am rebuilding. If I remember right the Simplicity 3414 was 34 inch cut with a 14 hp motor.
GC
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HV_Druck holzgas columbien pdf.pdf (3.1 MB)
brian, my first building guide was this pdf from a project from south america…
my first downdraft gasifiers from propane tanks has worked really well from the beginning…
first motor, a honda gx 160 runs in july 2020, first test run one hour to see if it works for longer time, it was very exiting …with not so much charcoal runs a motor!!!
only the nozzle from up, because made of normal water installation pieces was not ideal, and not keeps up for long, so i made the nozzle entering from the side…
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Thank you Giorgio for that building guide.
I used Google to translate it and, if I figured right, this is about what I want rounding everything to even INCH numbers.
I think my engines are about half the size of their 0.5-1 liter so I don’t know if I should try to scale this down or just try to find scrap close to these dimensions and hope for the best. My engines are pretty close to the honda gx 160 you used.
It depends on what I find and how ambitious I am but this at least gives me an idea for the next try.
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i have made it without fire cement ecc for weight reasons, and it is really not necessary to use them…
you see on the photos : the nozzle massive metal head is situated immediately over the part with smaller diameter (diameter about 20 cm, deep down to the grate 17cm)
hopper filling is for 4 hours engine run under load…long grass mower
also the 3kw peak electricity generator , 200ccm engine, also honda runs fine with this dimensions, but needs a bit more coal because of the fixed high rpm of the genset…the mower works fine with less rpm…
exhaust gas redirection is absolutely useful for nozzle protection…without this there was always a very little consume of the nozzle ss steel head in front ,with egr nothing…
another advantage of egr, there is minimal slag clinker production…without egr a clinker in the size of a lemon or also apple size can appear and this creates a ostacle for the gas flow…
ps…about coal production: when you shovel the hot coal in a barrel and the lid is not good tight, i give always a layer of ash, 2 inch high, or a bit more on top for sealing…ash is pressed, so air cannot get down to the hot coal…
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Garrt, Not sure about much. I don’t know where I got the 18 idea? Specs say 3414H is 14 HP. Thanks for the correction. BTW, any tips about this engine?
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Garry, sorry. extra characters
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Giorgio, Thanks for posting. Great info.
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I have ported the valve passages and milled.060 off of the head to up the compression. These two mods alone will add about 3 horsepower. These Kohler engines are in high demand for garden pulling tractors as they are so dependable and can be souped up quite a bit. Lots of good info for rebuilding them at gardentractorpullingtips.com.
GC
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As I think about how I can build this, I have some questions.
Assuming charcoal only, is there any reason to preheat the incoming air? The outgoing gases will need cooled so some of that heat could be used to preheat the air but that would mean I couldn’t use that nozzle opening to light the gasifier.
If the charcoal around the burn chamber is for insulation, could it be filled with ashes instead of leaving it fill up with charcoal?
My only experience now is with my simple fire, updraft and I get a pocket that needs poked to get the charcoal to settle back around the nozzle. Will switching to a down draft eliminate that need and only have to empty ashes that make it through the grate?
Also, in my simple fire, my last runs had some damp charcoal and I got a lot more condensed liquid in my filter and moisture on the lid when I refilled it. Is something like the WK gasifier uses to condense and separate that moisture from the hopper useful for this charcoal only down draft or should it (to a point) draw it through the hot burn chamber and convert to Hydrogen?
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Thanks Garry. Mine is a B&S. I think Simplicity switched to Kohlers in their 3414 in 1978? Somewhere I came across a guy that laps the head and block with valve grinding compound on a piece of plate glass and eliminates the head gasket to up the compression.
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No pre heating air is not necisary. We are not combatting moisture like a wood gasifier. Its almost the opposite. We add in water to cool the nozzle. The resulting steam processed is exothermic cooling the process down along with exit gases. If you are dropping water then you are adding too much water. If your fuel is wet and causing moisture, dont put wet fuel in your gasifier to begin with.
Dont over complicate it.
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100 pound propane tanks are a bit harder to come by than the smaller ones so I’m trying to get my plan together before starting to cut.
This is what I’m thinking.
There could be changes depending on what I might find as far as an ash hatch and that opening could possibly be moved down an inch or two but the bottom of the tank is rounded.
The actual burn pipe depends on what I might find. It could extend an inch or two down into the ash chamber and the grate might extend it a little lower.
I haven’t decided if I will cut the top off and make it removable or maybe make a fill pipe like my simple fire has. Maybe both so I could access the inside to change/check on the nozzle but the nozzle could be on a plate that would be bolted on the side.
If I understand right, this should give me more than double the run time that my simple fire does. The burn chamber alone is about the same height as my simple fire and bigger diameter.
I can only burn maybe half the depth of the simple fire (from the top charcoal level to the nozzle) before it shuts itself down but that gives me around 2 hours run time.
Judging by the burnt paint, it looks like the hottest part is around 8 to 10 inches from the nozzle.
The way I imagine the bigger one to be, the nozzle to grate distance as I have it drawn should end up about the same.
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Hi Brian,
I have this big roll of paper someone said I could have when we were cleaning out the basement of my church. Experience tells me that time spent making revision after revision on paper and cardboard saves time and grief when I’m cutting and welding.
Rindert
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Made the first cut. Even though this tank had been previously used as an air tank and I put some Baking soda and vinegar inside for good luck, it’s always a little scary.
Still in the thinking stage but I found a washing machine tub that could be the ring to hold the burn tube. Not as thick as I was hoping to find but it will be covered with ashes or unused charcoal to insulate it and direct the usable charcoal into the tube.
The tube is an old stainless steel soda concentrate container. It’s about 8-1/4 inches diameter but pretty thin and not easy to weld or braze. Still hunting for a better option.
I cut the bottom of the propane tank off mostly to make it easier to build or repair. Still debating how it will go back together but have plenty to do before I need to worry about that.
I cut the tank running the generator with the simple fire gasifier and the mixed charcoal with the finer flakes and it worked good but an angle grinder isn’t much of a load.
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