My YouTube channel HERE
*New* video of large gasifier operation HERE
Poor man's large gasifier Instructible
MIDGE small tin can gasifier Instructible
-------------------------------------------------------------------------------------------
This is the documentation of my largest gasifier experiment so far.
This unit costs about $50 to make.
After building a MIDGE stove, I wanted to design something with bigger,better performance.
It also needed to be a design that could be copied easily. All parts must be commonly available. Tools should be kept to a minimum.
This gasifier can be built in two quality levels. The prototype is identical to this silver aluminum model but is made from a large popcorn can using no power tools.
The output of this stove is very high. A very rough estimate might be 30-40,000 BTU. Don't quote me on that though. It can boil 5 gallons of water in 30 minutes. I've also mounted it under a 30 gallon gas water heater. After an hour and a half of runtime the water inside reached 150 deg. F
The stove will run for 1 hour without "in flight refueling". Wood pellets are the preferred fuel but literally anything "woody" can be burned in the stove. This stove burns material from the top down.
If burning wood scraps like 2x4 and pallet chunks, pack the wood in tight and cover with a layer of wood pellets. The top layer of pellets will create the initial layer of coals you need for nice combustion.
Much more can be said about stove operation. I will document some of this as I go on. Once you build the stove and run a few times on wood pellets, the operation becomes more obvious. When operated correctly there should be NO SMOKE emitted.
There are somewhat dangerous fumes produced by this size stove so don't use it indoors. Treat this device like a literal "campfire in a can".
TLUD stoves such as this are very safe in operation for the most part. The top ring of the burn pot gets incredibly hot (230 deg. +) but the sides stay cool (100 deg. or so) for the rest of the burn.
My stove uses a regular common computer fan for air supply. A centrifugal blower style fan is preferred but an axial fan can be used successfully if you make a straight duct and attach to the outer pot. Blower fans can be found surplus or can also be found in some Dell tower computers.
Improvise and adapt!
Now on to the plans........
Remove these ads by
Signing UpStep 1: Gather tools and parts
Tools needed:
- Dremel tool with fiberglass cutoff wheel
- Corded or cordless drill
- DeWalt 1/8 or 9/64th titanium drill bit
Components needed:
- 12 quart aluminum stock pot (buy quality restaurant grade with thick lid)
- 4 quart stainless steam table pot with "inset" top (Libertyware IP04 or Vollrath?)
- 6 quart stainless steam table pot bain marie(Libertyware BM06 or Vollrath ?)
- 12 sheet metal screws (pref. stainless)
Libertyware website w/part numbers:
http://www.libertywareusa.com/products/i/ip04.aspx
http://www.libertywareusa.com/products/b/bm06.aspx
Optional (if you can't cut the main hole perfect):
- wood stove cement
- high temperature RTV sealant
- Thermo Steel high heat putty
Optional tools for cutting main holes:
- Makita die grinder GD0601
http://www.toolbarn.com/makita-gd0601.html?ref=base
- Clesco M-3 wheel mandrel set (Holder for 3" stainless cutting discs. Can be used with Makita or corded drill)
http://www.drillspot.com/products/62526/Clesco_M-3_Screw_Type_Cut_Off_Wheel_Mandrel
- 3" fiberglass cut off wheels (Any brand with these specs will do. 3/8" center hole preferred)
http://www.lehighvalleyabrasives.com/servlet/the-99/3%22-X-1-fdsh-16%22thk.-X/Detail
These pots should be bought from a real restaurant supply store (or come from a restaurant).
I used Libertyware (Indian made), but Vollrath (USA) should work also. The Vollrath "inset" 4 quart is shaped differently I believe. Test fit before buying.
The burn pots are stainless, this is the only durable way to go. Use DeWalt or equivalent drill bit that is capable of drilling stainless. The point angle of the drill bit really matters. A Rigid brand cryo cobalt bit did NOTHING. It literally melted trying to drill the thin stainless. DeWalt titanium went through like drilling butter. It was a night and day difference. Will give part number of drill bit later. It's common at any Home Depot.
- Dremel tool with fiberglass cutoff wheel
- Corded or cordless drill
- DeWalt 1/8 or 9/64th titanium drill bit
Components needed:
- 12 quart aluminum stock pot (buy quality restaurant grade with thick lid)
- 4 quart stainless steam table pot with "inset" top (Libertyware IP04 or Vollrath?)
- 6 quart stainless steam table pot bain marie(Libertyware BM06 or Vollrath ?)
- 12 sheet metal screws (pref. stainless)
Libertyware website w/part numbers:
http://www.libertywareusa.com/products/i/ip04.aspx
http://www.libertywareusa.com/products/b/bm06.aspx
Optional (if you can't cut the main hole perfect):
- wood stove cement
- high temperature RTV sealant
- Thermo Steel high heat putty
Optional tools for cutting main holes:
- Makita die grinder GD0601
http://www.toolbarn.com/makita-gd0601.html?ref=base
- Clesco M-3 wheel mandrel set (Holder for 3" stainless cutting discs. Can be used with Makita or corded drill)
http://www.drillspot.com/products/62526/Clesco_M-3_Screw_Type_Cut_Off_Wheel_Mandrel
- 3" fiberglass cut off wheels (Any brand with these specs will do. 3/8" center hole preferred)
http://www.lehighvalleyabrasives.com/servlet/the-99/3%22-X-1-fdsh-16%22thk.-X/Detail
These pots should be bought from a real restaurant supply store (or come from a restaurant).
I used Libertyware (Indian made), but Vollrath (USA) should work also. The Vollrath "inset" 4 quart is shaped differently I believe. Test fit before buying.
The burn pots are stainless, this is the only durable way to go. Use DeWalt or equivalent drill bit that is capable of drilling stainless. The point angle of the drill bit really matters. A Rigid brand cryo cobalt bit did NOTHING. It literally melted trying to drill the thin stainless. DeWalt titanium went through like drilling butter. It was a night and day difference. Will give part number of drill bit later. It's common at any Home Depot.
Visit Our Store »
Go Pro Today »
You can measure the bottom of the pot diameter, then use a circle drawing tool to mark the hole.
I had an MSR 4 quart (I think) stainless camping cook pot. It happened to be the exact size. You see this in the first pic. I just set it on top and traced around it.
Next step is cutting the hole. I used a dremel with reinforced fiberglass cutoff wheel. Pic 2 of this step. Dremel and fiberglass cutting wheels are available at Wal Mart/Home Depot etc.
You hold the dremel just like in pic 2, then let the spinning wheel "sink" into the lid. Move the dremel in a circular path along your marked line (hold with both hands very steady). Think of it like a "can opener" action with you moving, not the can.
Of course make sure the pot/lid is held down to the workbench securely. I did mine freehand but you have to have some skill with a dremel. And wear eye/face protection. The fiberglass wheels disintegrate easily while cutting. Stainless metal shards will also fly everywhere. Don't breathe any of the dust in.
Hope this helps clarify!
Thanks for the detailed reply. I have a clear idea of what to do now.
One quick note, you mention stainless metal shards but the stock pot you and I are using is actually aluminum, correct?
Thanks,
tXm
In both cases you have to watch out. Cutting with any fiberglass cutting wheel is messy and somewhat dangerous.
Oh, cutting the hole in the bottom of the 6 quart pot is done the same way.
I made it square cause I ran out of small cutting discs. All I had was a corded drill with mandrel and 3" cutting disc. The corded drill was not high rpm enough to cleanly do the circle. I just did straight lines instead.
I'll update the main instructable with some alternate cutting tool info. Will show a Makita die grinder and the mandrel that holds 3" cutting discs.
-tXm
I cut the duct opening very tight. It holds the fan pretty tight all by itself.
The fan does just fine. Not hot at all. This is due to the double burn pot configuration. The outer burn pot keeps the heat concentrated on the inner pot for the most part. The large outer pot only reaches around 100 deg down near the bottom. This is the beauty of the multi pot solution.
Automotive header/exhaust manifold tape would be a great addition to the 6 quart pot:
http://www.summitracing.com/parts/THE-11002/
It would keep the heat contained in the burn area. The entire stove would probably be cooler on the outside surfaces.
Experiment away though!
If you come up with something that works, I'll add it to the Instructable with credit.
I bend the top holes in order to have a nice swirling flame; I think it helps mixing the wood gas and the hot air and concentrates the flame in the center. It melted my aluminum pot stand right away!
Once started, it boils 2 cups of water in less than 3 minutes.
Now we just have to make a simple shroud for the fan to keep rain off.
Use metal wall studs from Home Depot to do ducts and boxes etc.
One stud can make tons of experimental ducts.
Cut with a good pair of tin snips. WalMart has yellow/black handled Stanley brand for cheap. They have serrated edges that helps the blades grab the metal.
I do like your aluminum box tubing as the duct.
What exact size is it?
Can you take a pic of the fan label up close?
And the air duct exit on the fan....
I can't take picture right now (forgot the stove at camp for the winter), but the duct is made with 1" square aluminium tubing (1/16 thick). For now, it's just tape to the fan with electrical tape. I'll glue them together with something more tough and durable, maybe some Sugru. I insert the duct in a 1" x 1" hole on the side of stove. The fan and the duct can be stored in the burning pot when not in use.
Speaking of Sugru, I think I'll put some spot of this stuff on the side of the stove, so I can manipulate it when hot, without a separate handle. Tried it on my pot handle, and it works great as a heatproof coating.
I might also try to make the connection between the air duct and the stove really air tight with this stuff. But it's not really necessary.
You could add an air duct between the blower and the side of the stove, where a slot would allow a door to partially close the duct at will. See the small sketch.
The flap can fit really shoddy, cause you only need to slow the flow of air a little.
On my big stove? No. I used some heavy expanded metal as a grate while boiling 5 gal of water. It melted the steel and made it droop in a huge circle below the giant water pot.
That's an amazing amount of heat.
It's in french, but the pictures are enough to understand.
The guy use a double wall stainless mug. There are a few 20 oz mug out there that would be fine for my need. I'd prefer a bigger stainless wine bucket, that is also double wall (about 4" x 9"). It's rugged, and all you have to do is drill holes and make a potstand. It's a bit more expensive than tin can, but will last way longer!
That's my next project!
Here is something you need to do.
The inner burn pot needs holes around the bottom. Drill these by sticking a 1/8" drill bit *through* the outer bottom holes in your picture.
Then make a cowling to enclose the bottom holes and provide fan air into them.
It does not have to be airtight. It can be a base "unit" with circular hole that the pot shown above can slide down into. This can also protect the fan, making it rainproof. Would also provide a more stable base for the "pot"
Also his top holes are too large. A double row of 1/8" are all that is needed.
Actually all holes in the pot pictured can be round. Square is just extra dumb work.
Let me see if I can do a quick illustration in a bit. It's easy and would be worlds better than what he did.
Thanks for the idea. To drill the inner holes at the bottom, I was going to drill through the outer bottom, then block the outer holes with JB Weld. I'd drill a bigger hole to serve as an air intake for the blower, just like you did in your instructable.
I figure I'll be able to drill the top holes from the inside, drilling at an angle. You have experience with stainless: what do you think?
Stainless is very hard to drill. The drill tip has to be the correct angle.
DeWalt 1/8" gold titanium bits go through like butter.
That's what I used to do this instructable.
A Rigid 3/16" cryo treated bit literally melted in 20 sec.
It glowed cherry red and almost didn't make it through the stainless.
Illustration coming up...
And when not in use, the base can store the batteries and solar panels you have. Just stick them inside the round hole.
The fan and stainless gasifier part have standoffs in bottom so water getting inside does not go in fan (and gasifier heat stays off the bottom of box).
I'll consider building the base. Would be really heavy duty, and solve the weather problem (I'm in Canada... where weather often is a problem.)
Glue the box together with wood glue and also use tiny nails.
It should withstand the heat.
Bottom pot standoffs could be stainless screws with the tips ground flat.
Or stainless machine screws. Just predrill tight holes.
http://duplicolor.com/products/truckBedCoating/
Plus, the stove wont sink into snow easily.
This is the winner in commercial stoves:
http://www.biolitestove.com/CampStove.html
It's self powered. The TEG inside powers the fan and can charge a cell phone too. No batteries or solar. The custom fan is the only moving part.
Here is the setup iI settled for:
- a 5V blower fan
- two solar panel in parallel (1,715W) that can directly power the fan in sunlight.
- a 4 AA (NIMH) battery pack, that can be recharge by the solar panel.
On the picture, the fan is only powered by the solar panels, and it runs full speed. I'll be able to save batteries when it's sunny. Moreover, you can easily control the speed of the fan by covering/uncovering the panels!
What is the model/part number of the fan?
Would like to see how many CFM it is.
It's a 5V x 0,15A and measures 50mm x 15 mm. It was listed as 15 cfm. Seems like enough power for the size of my stove, whick is a bit smaller than your. Anyway, I will try a bigger one: 5V/0,18A; 75 x 25 mm.
http://amzn.com/B005AKCNBY
Where did you buy those specific models of fan?
They sound about right CFM wise.
My 24 v fan runs very slow. It's not a blast furnace thing.
I have a 5v USB adapter for 12v cig. lighter socket. I could run 5v easily too.
There are also 12v laptop power supplies with an accessory 5v USB receptacle on them. I'm going to hook one to a Ryobi cordless tool batt pack. Having a USB jack is bonus.
That large 5v Amazon fan looks good. It has accessory mounting holes all over it.
It would be perfect to mount a rain cover for the fan.
That's going to be my next addon. I want the big gasifier to be all weather.
I'm from NY. It rained all the time there.
And of course it's going to be rainy cold when using a gasifier outdoors.
You could use duct tape and folded tinfoil...or thin sheet metal cut to fit.
Each fan is going to be different.
Around the camp, I'll use a 12V power pack with an USB adapter. On the trail, I'll use the pack with 4 NIMH batteries (4,8V); it last for about 8 hours.
Why not clamp or "jig" a fixed hold for your dremel, like a reversed (upside-down) circular saw (to hold it in place as shown in your photo). Drill a 6mm hole in the centre of your pot lid and sit it on a pencil (or somesuch) as a compass point, then rotate and cut. Almost "Score" the lid first and then adjust. Cut mm by mm lifting the lid (evenly) to the blade after each full revolution.
That way you will get a beautiful and even cut. The only thing that I would look out for is the wear on the blade. This is because, although the front tip does the cutting - it's the REAR of the blade face that gives you the shape - thus as it wears down your diameter will change.
Give it a go though, you can always buff it if you need it SUPER-perfect eh ;)
Good luck guys, I want to give this instructable a go myself so I'll post you some photo's soon too.
Cheers.
I've been working on one of those, and I thought I'd share my thoughts.
The stoves : After a few tries, I settled for this: a 23 oz coffee can (6,5’’h x 5’’d) and a one liter can for the inside. You can go smaller than this (ex : with a quart paint can for the outside and a 20 oz can inside), but for what I know it doesn't contain enough wood to be really practical. The 23 oz coffe can is small enough to carry it in a backpack. The only problem is the rust: Any suggestion for a good paint for the outside?
I’ve try a wood gas stove without a fan (a homemade bushbuddy), but got too much smoke for the taste of my girlfriend. Maybe the air intakes were’nt big enough.
Anyway, I will try a 5V computer fan (50mm x 15mm). I didn’t try it yet, but the numbers seems right. For the same size and current, the blower type (see the picture) seems to outputs way more airflow than the blade type. Moreover, the airflow seems to be easier to harness. Since it's only 5v, you can power the stove in the field with a battery pack (4 rechargables AA= 4,8V), that should give you a few hours of autonomy. I’ve tried a 12v fan, but the 9v batterie didn’t last an hour. The 12 v seems the right choice around the house or the car, but on the trail, I’d rather carry fuel than a 12 volt battery! According to the specs, the 5v does’nt blow a lot less than the 12v. Anyway, I might upgrade to a 5v 70mm x 30mm. After all, my goal is not to melt metal with this thing, just boil some water on the trail.
Also, if you install a USB male Jack to the fan, you'll be able to plug the stove in almost any USB outlet! Including the MightyMinty Boost(see the instructable by Honus)! Heck, with a good sunlight, you might even try to power the fan directly from a solar panel! You only need 5V x 0,15A =0,75W! (Am I right?) There’s a lot of cheap and small panel out there that will do the job. Anyway, this is all theory. Anyone has experimented with a 5V fan? Any suggestions?
The other problem is the connection between the blower and the stove. I want to save some weight, and more important, time and trouble. A good way to join the blower to the stove would be a 3'' silicone coupler; that is readily available and can withstand up to 500F. All you have to do is glue the tube to the blower, and insert the tube in a close-fitting hole at the base of the outside can, and take it out once your done. This way, the blower will be isolate from the heat. One would be able to store the blower and the battery pack inside the stove for transport. Any thoughts on the tubing or duct? I know some people built duct from scratch..
Hope I’ll be able to try this soon!
Start here....
Maybe because the briquet have already been "gasified", kinda like the char cloth...
http://www.youtube.com/watch?v=Kb5tWYn4-cA
And look into the different designs out there. Read some of the research papers.
any help would be great,
K
anny way its a pretty sweet build probly usefull if you go camping were there are fire bans making it almost impossable to get caught (no smoke)
Regarding adding the combustible fluid, do you think pouring it into the main vessel would mean some of it would drip down and ignite the pellets in the middle?
I've read elsewhere a small amount of pellets should be soaked separately then added to the top, so the burn pattern is strictly top-down.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310148993913&ssPageName=STRK:MESELX:IT
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310209561834&ssPageName=STRK:MESELX:IT
I wonder if you could attach a peltier device to have the heat generate the power to run the fan? or you could use a thermopile like the Stovetec rocket stove.
There seem to be a lot of similarities between rocket stoves and wood gas stoves, or is that just my imagination?
Thermoelectric (Peltier/Seebeck Effect)
en.wikipedia.org/wiki/Thermoelectric_effect
A TEG/peltier unit big enough to run a computer fan is $$$$$$.
Better to use 8 AA rechargeable/solar panel charger combo.
Or like I did..use a jumper pack and a larger solar panel. You can then supply power for a household/camp.
Rocket stoves are weird old school. This is more like science. You have to build one to see this.
There are several fan/forced air stoves around, but they all seem to be electric. I was wondering if someone has ever tried doing a thermoacoustic or stirling fan for these stoves. How much air does the fan need to move?
You need to be able to power a computer fan. Start your calculations there.
20-40 CFM is ballpark. Energy varies by fan unit. Go look up some specs.
Biolite is making custom low power fans with optimized flow paths so they don't need to use big TEG modules. As the power requirements go up, so does the need for a more $$$$$ thermo power generating unit.
Don't wonder about it...buy some parts and MAKE an Instructible!
I'm working on collecting the pots from thrift stores and trash piles (nothing like living a half-mile from a college in an student-centric neighborhood) so it's a bit more slow going. I also don't get to be as specific about dimensions. I have a very sturdy inner pot although I think it's a little small for the job -- nonetheless, it'll work. I have an eye on a couple more larger pots but we'll see.
I thought woodgas camp stoves were the most efficient stoves but StoveTec Rocket Stoves claims their stove design is the most efficient.
What do you think?
I wonder if you could do without the stove fan if you had a taller stove with the fire near the bottom? Then the draft of the air going up the chimney would suck the air in like a fan.
http://www.bioenergylists.org/andersontludconstruction
See the problems with them?:
http://www.bioenergylists.org/content/testing-andersons-tl
Forced air fan stoves rule. They work in any wind conditions. Mine does not go out even in crazy wind outdoors with NO windbreaks.
I use it to run a 30 gallon water heater. 1hr burn (1 pot full) of pellets gets you over 100 degrees in the tank. Another half burn and the water is up to 150 deg.
Never tried a two hour burn. Water might be too hot to use.
Video coming up in the future showing this.
Thanks for the very good instructable!
The burn goes along fine even with those small side holes. Only a tiny bit of ash is left once it's done. You could do about 4 one hour burns before needing to clean the pot out.
Plus, with only side holes, the inside of the stove stays clean.
I think most of the commercial TLUD type stoves have a solid bottom too.
Going to try less holes again on the next burn pot I build. I just did a small stove from a paint can and a 1 1/4 quart stainless pot. It burned for a solid hour with only 7 of the 1/8" holes on the bottom of the burn pot.