Tom Collins' Gasifier

SteveUnruh · August 31, 2018, 5:58pm

Maybe a bit out of the current exchanging info flow but grate types and WHY’s of it, are important.
VesaM makes very thick stout grating with a mechanical driven above the grate sweeper (crusher/grinding) arm. Why? he wants his systems to be commercial available in his area, peat-fuel (sod) capable. This peat-fuel has a higher than woods mineral ash %. That ash gathers up, collects, and clinker lumps melts together. He has to have the capability of his systems to grind up these clinker chunks and pass them though. Plus handle an occasional carried in with the peat-fuel cubes, small rocks. So woods, any wood are a snap with his grating systems.
I/we/us in many parts of the world have available only soft char making woods. Wonderful usually for low mineral ash percentages; and that ash usually having high melting points. But these soft structured wood char chunks crumble easily versus the hardwoods chars. The soft structured wood chars really easily turn most systems into a gross soot makerers.
So need a grate that does NOT have any up and down chars crushing motions!
Experiences say the maximum char-to-gas with the least soot is with an outer edge flow around grate system. The actual grate grid very fine grate opening (to hold up the progressively smaller and smaller char chunks into active zone use) versus an ALL-must-flow trough grate. If it is to the perimeter extended, perimeter supported grate it must be an ALL-must-flow-through grate. Super picky then on grate-grid openings sizing and the opening shaping to needs-must be flows through capable…

ALL-must-flow-through grates; and non-active grating are VERY dependent on gas-flows velocity/volumes to effectively ash clear. This limits an IC engine very low idle-fuel to fully loaded range of power useages.
A command active grate with edge flow over by-passing give back the widest gas production range with the widest range of fuel woods in my experiences.

Ha! Ha! And a grate edge low fence perimeter save with soft structures wood char the maximum char for gas conversion. An operation concern for those of us who intend not to be charcoal makers. With my low carbon to volatile ratio Dough Fir woods I have not the excessive carbons to be an even adequate for later use charcoal maker. Need it all in-gasifier to relevantly convert as much as possible all of those volatile’s pitches and tars excessive oxygen’s and hydrogen’s in my base fuel wood species. A must in my area to not produce toxic end wastes.

So can you all even begin to see?
NO one type, or size of shoe, or hat, could ever fit best for all. I change shoes and hats sometimes daily and certainly seasonally to adapt to actual needs.
tree-farmer Steve unruh

KristijanL · August 31, 2018, 7:03pm

I agree Steve! There was a time when the size of a shoe or hat didnt matter, as long as it remotely served its purpose, a time of ww2. So was with gasifiers it seems, but luckly we live in times of peace (for)now, so we can afford a lot more customisation.

You proposed some good tips. I guess in a way WK gasifier does the same, sliping some char. Perhaps l need to start thinking in this direction…

gasman · August 31, 2018, 7:47pm

Hi, Steve!
31.8.2018

You now seem to forget the third delicate methode to differentiate char from ash:

Upstream sifting! By Imbert, etc.

The upstream char is always clean… provided there is an approprate grate below.

KristijanL · August 31, 2018, 7:54pm

But not of slag, as was the case with my updraft reduction wood gasifiers. The damn thing just accumulated…

gasman · August 31, 2018, 8:03pm

Hi, Kristian!
31.8.2018
OK, with “mineral” wood the temperatures are decisive for melting minerals or not, keeping them as dry ash.

If I remember right, you used no grate at all?
Or only one circle - grate above.

KristijanL · August 31, 2018, 8:11pm

Correct, no grate.

Absolutely, but how to keep the temps down where we want them as high as possible (restriction)?

gasman · August 31, 2018, 8:14pm

Hi Kristijan!
31.8.2018

By decreasing nozzle-blow velocity. That sets the whole process temperature.

(Or using the “Rindert methode”) mixing in exhaust in the primary air during top power stretches…
It can be automatic by temperature controlled exhaust inmixing staring at ~ 1100*C restriction temperature.

You can perhaps at your “own” laboratory measure melting and flowing temperatures of the kind of slag you have “manufactured”?

KristijanL · August 31, 2018, 9:03pm

Hmm now l wish someone did try the EGR on a wood gasifier. Wonder how it effects power output… l know what shuld happen, but gasifiers tend to defy natural laws sometimes.

Well l guess l culd try melting it but determining the temp might be a problem.
I wonder… culd to small oxidation zone allso effect slag formation? Myne were allways on a small side.

gasman · August 31, 2018, 9:19pm

Hi, Kristijan!
1.9.2018

“too Small”, if you go under 5% of the “Sekundenverbrauch” at

Autobahn WOT…

Easy to calculate, if you have a RPM meter.

Is it hard to do “private” measurements at your lab?

Radiation meters take the temperature at a distance…

pepe2000 · September 1, 2018, 3:03am

Hi Kristijan,
Here’s a few pics of how I built my adjustable grate. I used Line D dimensions for nozzles, restriction etc. for my particular HP range.
The grate is shakeable via an outside handle on the bottom of the cleanout area. You have to shake
the grate with a back and forth action to get a feel for clearing it. Once you’ve cleared it (the ash clog), the gas production will resume in its normal manner. If your running a gas engine it will lose rpms, cough and then resume as before. They can be automated,etc. When running, I usually clear every 15 mins and it keeps my generator running smoothly. Take a hint for clearing from the lowering rpms. You want to keep that char bed as hot as possible as long as possible.
I’m hunting for the vid I made for making the grate basket.
Hope this helps.
Pepe

In the upper left corner you will see the imbert dimensions and on the right, the closest material
I had on hand. This all worked out well as a gas maker.

Loosen to shake, then tighten again to insure air tight connection.

gasman · September 2, 2018, 10:18pm

Hi, Pepe!
3.9.2018

Well performed traditional reduction – filtering, with its

“baked – in” property of selfclogging.

Constantly needing outside intervention of some sort; babysitting or timed mechanical releif handling…

Some time ago Kristijan attempted sifting with the exiting gas stream – with success.

Upstreaming sifting from the periphery of the reduction char.

Then the gas can be cleaned in an efficient cyclone, which is easily emptied at longer time intervals.

===============================================

The sifting downward can also be performed:

Fredrik Ek rebuilt his gasifier system many times.

One stage was built in a fashon with a conical metal cone enlargening from the restiction in 60* downward, ending with a large grate (whole-area).

This had a notorious habit to clog all the time; independent of

full – gas driving on a motor – way, or slow town traffic.

But with covering the cone – bottom with a whole plate, with an exception of a center area (effective area) in a smaller grate – area

equal to the restriction area the reduction char kept itself clean and functional.

This, on open road conditions, but in town trafic it started clogging again, opening fast again on open road.

The profile of the active (moving) char was like a prism;

first 60* outward, and then 60* inward to the grate opening.

===============================================

In a traditional Imbert GMR with a “tight” whole area grate,
the ash is mostly blown outward to the periphery, where the velocity is lower.

If the restriction is prolonged half-ways down to the grate,
still, with the same diameter, one can expect to start a vertical hemispherical circulation where the peripheral region goes in up-stream.

The grate has to be a solid plate from center to the half, or better 3/4 – diameter in order to link the downstream initially horizontally, thereby helping the hemispherical circulation to start.

This is the foundation of vertical sifting, if the gas out-take is placed high up under the restriction-plane (screened if avoiding char-blow is wanted).

In this direction Kristijan was building… going further with no ash-bin at all.

The out-take has to go around the heart (at the restriction hight) for getting symmetry.

KristijanL · September 3, 2018, 5:47am

I hope @JO_Olsson chimes in here with some pics, his new Mazda gasifier is wery similar to the upstream reduction grateless gasifier l had. He reports great sucsess.

JO_Olsson · September 3, 2018, 9:10am

Haha, I wouldn’t call it great success, but it works I’ve never had any severe plugging with this gasifier. Actually it sifts fines out so good the charbed gets a little too loose on longer open road trips. I waste a little more char out the cyclone than I like and I have to be careful not to pull too hard.

These might be the only pics I have from below.

4" restriction. Adjustable in hight. Top side has a flange which sits on a surrounding spacer ring.

8" lower firetube. The void between it and the restriction is filled with ash from above.

12" housing. Makes the “sifting gap” a little less than 2" wide. A little wider wouldn’t have hurt. Or maybe two outlets to slow things down a bit.

There’s no grate and no cleanout port.

The drawing is not in proper scale. For example it’s not as tall from restriction to housing bottom.

trikebuilder57 · September 3, 2018, 12:03pm

There’s no grate and no cleanout port. I some times don’t see thing right off, but how do you clean out the char, and ash? Thanks for posting.

KristijanL · September 3, 2018, 1:04pm

If you are lucky as JO is, you dont the updraft gas stream does that for you. I however neaded to empty it quite often, reason is my nutorious slag problem but for most woods, this is quite self cleaning. I cleaned from the top, the restriction cilinder wasnt welded in and culd be pulled out.

This is how mu Chevy and Mercedes gasifiers looked like

This is what happens in operation

When the gas flow shifts upward, it fluidizes the charcoal ads sweeps it of dust. This fluidization allso prevents charbed constipation, but like JO sayd, it is more prone to overpulling- if the gas velocity gets to high it can blow a hole in the charbed wich resaults in weak hot gas.

k_vanlooken · September 3, 2018, 1:20pm

The best quote i ever could make…

Note to all: you could copy whatever you would like… but your skills to understand your copy and to make it run are to be learned by doing…

TomC · September 3, 2018, 1:26pm

Thank you all for continuing this subject in one place. Max post his knowledge on many of our threads, and JO posted most of his build on his thread and Kristijan posted his build on his thread. This has brought them all together. It makes more sense to see altogether and compare them.
I would like to ask JO-- how did you “size” your nozzles as they are in two altitudes above the restriction?
Now that I understand this “grateless” design, it makes me want to cut the bottom out of my gasifier and remove the great so that I could lower the height of the entire gasifier --Kidding, I haven’t even got my truck back in the shop. Thanks again for clearing up this subject. TomC

k_vanlooken · September 3, 2018, 1:30pm

Slipped char is not wasted if you ad it to your new fuel batch … And: slipped char also means less energy wasting CO2 in your gas… if you have only grey ashes out, it means no excess carbon present
This also works for complete combustion of wood, excess air is needed to completely burn the carbon…
In this case ( gasifier ) i think its preferable to have some char that slips…
Also: the char will adsorb a certain degree from descending Tar’s, if any,

If ever have the opportunity to sit next the “champ” (Wayne) then you would understand that some slipping char does not do harm to the engine and acceleration… ( LOL )

I miss that feeling, can’t wait till next time… so i will build me a char slipper…

TomC · September 3, 2018, 1:47pm

I wear a size 10 if you would like to build a pair of “slippers” for me. TomC

KristijanL · September 3, 2018, 2:04pm

Well its not so much that l feel bad for the “wasted” charcoal, it comest most usefull in the garden, but its the extra space that the sliped char needs. Imagine fiting a full power 20l/s wood gasifier, cyclone and ashbin in a mufler compartment with dimensions of 30x30x50cm, while it all must be insulated so well it is cold to the touch. Thats the bull l wresle for the last couple of months

Haha, l wached the video a 100 times. The glow in your eyes when Wayne presses the pedal says it all