a question on the restriction zone.

Comment

Comment by len von speedcult on June 3, 2009 at 4:10am

The condensate from those test runs last fall was definitley black (not clear). The filtration was not a priority when I did that . I just wanted to see if I could make gas. How can you guarantee a clear condensate ? Is that just a function and result of a cleaner burn ??

Comment by Daniel on June 2, 2009 at 9:49pm

had a look at your photos hard to see your gas burn in the light of day.....just improve your filtration.....and Keep a eye on the color of you condensation from your gas cooler (should be clear)

Comment by Daniel on June 2, 2009 at 9:34pm

Gas Color

Len said his gas burn was “clear with a tinge of orange at best “ in my experience this would indicate good gas.......... you will only see blue at night, that is the clear flame (Hydrogen)..... the tinge of orange is carbon burning after being preheated by the hydrogen burn.

Orange would indicate to me that you have a high content of carbon either from ash, char, sot or (co)carbon monoxide

Yellow or Red would be very bad !!!! tar and creosote !!!

Comment by len von speedcult on June 1, 2009 at 9:48am

some pics are posted. They're all from last summer/fall. I'm going with an inverted V design now.
Before I went this route though I had to have a better understanding of what exactly is going on in a reduction tube since my design design really didn't have one. Thanks again for everyone who helped me understand.

Comment by len von speedcult on June 1, 2009 at 9:02am

Thanks everyone for painting a decent verbal picture of whats goin' on in there. I had OK results last fall with my project when I used just a V (not inverted) style reduction . Basically I just transitioned from my 12" diameter inner hopper tube to a 6" diameter via 45 degree cone. On that 6"
diameter was a grate that bolted on via a flange ring. It worked but was prone to clogging since I could not shake any ash out and was reliant on it just "falling through the openings". It made gas..
never the nice blue stuff....clear with a tinge of orange at best. I'll try and post some pics if anyone cares to see. len

Comment by Adam on June 1, 2009 at 8:54am

Yes and BTW, you don't want to block the tube with a grate at the top. The Imbert reduction design is basically gravity-fed. The charcoal 'falls' and is funneled into the tube as it is reduced. The key is to keep the charcoal hot and moving. The inverted cone is basically a clever way to prevent charcoal flow from getting blocked up in the tube. It's a nice-to-have, not a need-to-have IMO.

-A

Comment by Adam on June 1, 2009 at 8:41am

Yeah from my experience, the grate/cone combo is just enough to stop the charcoal chunks from falling into the bottom. On first startup, you fill up the whole thing (restriction tube and all) with ~2" charcoal chunks (hand-broken and picked) until about 3 to 4" above your intake nozzles, and then fill the rest with your wood chunks. As the charcoal heats up and turns to char, it falls through the grate and gravity does the rest to repeat the process. So if you're using an inverted-V reduction tube, your grate will need to be just wide enough to prevent the charcoal from spilling out from the sides when you fill it up. If you keep a good charcoal bed, you hopefully won't need to do the whole charcoal startup thing again - just add wood.

-A

Comment by Steve Unruh on May 29, 2009 at 4:38pm

Not bridging, stacking up. The whole reduction tube/cone needs to be filled up with char/charcoal up even to the nozzle level to have enough reactive pass though time and surface area to convert the produced noncombustable H2O, CO2 gases into combustible H2 and CO gasses. Confusing at first to understand. Read/look at as many different explanations as you can find - they all say the same in the end. Do watch out for confusing artwork.
Those who have tried restriction area bars have found they are blocking the needed charcoal migration into the Reduction area. The water vapor and carbon dioxide ( and tars) will pass through and out unreduced into the simpler combustible hydrogen and carbon monoxide gases.
Good if you are trying to make a heating stove - bad as a fuel gas producer.
Regards SteveU.

Comment by len von speedcult on May 29, 2009 at 1:52pm

Thanks for both of your opinions. They do differ but thats ok. On this statement from SteveU.
" The uncarbonized wood chunks are physically being held above the tube/cone by stacking up and their size.". Soooooo...we have to be dependant on some constant level of bridging???? Hmmm. that sounds chancy???..might happen..might not. Thats why I was wondering if some sort of single rod or crossed rod grate at the the top of the restriction tube would be in order.
If the bridging Gods don't smile on you it would be feasible for the wood chunks to just drop through
and fill the whole tube and grate???

Comment by Steve Unruh on May 29, 2009 at 10:26am

Hello
Just above and within the Reduction tube/cone you have two completely different thermal/chemical processes taking place. The uncarbonized wood chunks are physically being held above the tube/cone by stacking up and their size. With a small "controlled amount of air" allowed you are sacrificially oxidizing the heat driven out volitile hydrocarbons to produce the heat that makes ALL of the other three processes work. Moister drying of the fuel at the top; higher heating driving out of the volatile hydrocarbons next step down and below the the oxidization zone the actual Reduction process must start out hot because it will absorb heat.
The remaining smaller white hot carbonized char wood chunks now settle down through the restriction opening and you do want them to stack up in tall pile. It is when the uncombustable gases produced in the upper zones are forced past the new glowing red hot charcoal pieces the you get the thermal/chemical change to combustable gases. The word Reduction refers to this chemical process, but is also handy for understanding what is happening to the physical size of the char pieces: they get smaller and smaller as they are consumed in tis process. A tube restriction needs an internal grate to keep the char pieces inside, but can suffer from gas flow thru impediment from the small char unless allowed to fall thru and be "wasted". The cone reduction tube tries to mimic the shape a pile of char would form if slowly poured out. Good flow thu capability but unless you can keep suppling enough new hot char on top the pile and NOT lose to much thru the grate the upper uncomustible gases can channel bypassing the red hot char unchanged. SO tube or cone have to do the same thing, but pros and cons to each.
Bens vidio shows these zones and processes and in the Links and Reports sections you will find other explanations with more or less pictures, math, chemical symbols. All say the same thing presented differently.
Regards SteveU.

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