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There was an earlier mention of animal dung as a fuel. Now I have a 1 year old great dane pup as some of you know. Well I have to clen up after him and so guess where it goes if I am forging? It results in some interesting colours in the flames but does burn. I don't think I would want to use it as my sole fuel but cocktailed with my smithing coal it is OK. I frequently use wood as a fuel without any problems. It is just bulky!

Interesting. May I ask what you feed him on? I'd have thought that only herbivore dung would work, due to the large amount of cellulose etc. (the undigestable parts of grass).
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Ice Czar, after taking in your comments about too much air and reading the superficial velocity paper, I tried using less air and less wood and got pretty good results. I had been thinking that the pyrolysis was keeping the temperature down, and designed (arranged?) the setup to keep the pyrolysis happening before the material reached the firebox. Most of the pyrolysis gasses were burning in the air before, keeping them in the chimney more retained some heat to transfer to new wood chips. The pic is pretty much the current setup, there are 1/2" spacers under the top bricks to let more air into the chimney.

I'm now thinking of building something like a big MIDGE (mostly taller) using air from the bellows or a small blower, and an oven over the top. This would be more or less a continuous updraft setup, maybe started by filling and burning down. If I do use the bellows, how quickly will the gas fire go out without draft? I guess the charcoal fire would not reignite it like with the MIDGE, since there will likely be material in between. :( Could I use a small tube with natural air draft for a pilot?

I visited the Indian site linked to from the Woodgas site, their design is very close to what I drew up, but mine would run the other way.

While playing with the MIDGE, I happened to remember there was a grill on the market about 20 years ago, the TV ads claimed it would cook delicous hamburgers using just a sheet (section?) of newspaper. I'm thinking it must have been a gasifier. Anybody else recall that gadget?

Thanks for all the help, and as always -
Good Luck!

Oh yeah, I've got about half the tools on your list, the major ones I don't have include the MIG and plasma cutter. But mainly it looks like you have a lot more skill and experience! :)


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Yes, I remember the ad. We used the following long 20 years before the ad ran on tv.

You can take a half gallon size fruit juice tin can and the old style can opener and do much the same thing. Just make 6 *V* shaped openings on the SIDE of the top of the can. Make two on the SIDE of the bottom of the can and with a knife form a small door. Bend this to the inside of the can for safety so you don't get cut.

Place some very small sticks inside the can, not many, just enough to start a fire. The heat will rise in the can and out the air holes in the SIDE of the top of the can, heating the cooking surface (the top of the can). It makes a nice little stove that is very fuel efficient. A little dab of bacon grease, some food, and your meal is ready to eat in short order.

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I visited the Indian site linked to from the Woodgas site, their design is very close to what I drew up, but mine would run the other way.

its strange you should mention that, Dr. H. S. Mukunda's design had a major influence on my design, what Ive cooked up is basically a cross between his and Das Agua's Dasifier, instead of the hot producer gas being draw up the jacket however (image below) I'll burn it first in the forge (adding even more heat) then duct it back up and out for treatment. the other advantage is that it can be executed for the most part as pipe (as opposed to slip rolling various tanks and cones like you see in the old style designs)

what your describing is an updraft gasifier which is kind of what the MIDGE is (inverted downdraft is updraft :P ) there is quite a bit of info on updraft gasifiers, they produce quite alot of tar and because most gasifier development is about producing syngas to run an engine they havent been the focus of that development. Fuel is still gravity fed downwards, but the draft is from the bottom up.


Wood waste is admitted to the gasification chamber from above, falls onto a grate and forms a fuel pile. Air from below the grate (sometimes accompanied by steam) is blown up through the fuel pile. Since the flow of fuel is downward, towards the grate, and since the flow of air is upward, up through the fuel pile, this type of gasifier is also called a counter flow gasifier.

As the wood waste works its way down th the grate it dries. its volatiles are pyrolyzed and its fixed carbon (also known as char) is converted to carbon monoxide. In the process some of the char is completely oxidized to liberate the heat needed for evaporation and pyrolyzation. The carbon dioxide, so formed, is usually reduced to carbon monoxide as it continues its way up through additional layers of char to the top of the fuel pile.

The producer gas leaving the gasifier is at low temperature. It is laden with condensed tars and oils from the pyrolyzation as well as particulate matter picked up during its passage up through the fuel bed

that gives the three reasons I went with a Dasifier instead of an updraft, low temperature gas (since Im using it immediately the higher the temp the better, particulate matter that may or maynot get burned in the forge, and lots of tars that may or may not be fully combusted in the forge.

Image Dr. H. S. Mukunda of Indian Institute of Science

Dr Mukunda's CGPL at IISc, India renews faith in gasifiers.


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Being new to the concept of gasification, I've been trying to find all the material that I can on it. Here's one I found interesting, it mentions gas temperatures; updraft 80-100*C, downdraft 700*C. It also says "... updraft gasifiers are usually just operated in a close-coupled mode to a furnace or boiler..."
Industrial Uses of Biomass Energy ... - Google Book Search

Here's another one where they tout efficiency converting fuel to power, one of the advantages they claim for updraft is "The updraft gasifier features a high carbon conversion and high cold-gas efficiency (a measure for transforming chemical energy from solid fuel into gas)." Of course leaving the tar in the gas means it has to be burnt later and the temperature raised more, I'm hoping that isn't too big of a problem.
Babcock Wilcox V

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  • 3 weeks later...

New to the forum, thought I'd jump in.

Like a few of you, I have been searching for what I could about the Gasification, but I am trying to get in to casting and melting, no smithy till I come across a good anvil. Start out easy then work my way up.

I came across the Dasifier, and I got nosey, so I called Das. (yes, the phone number still goes to him) He told me that he has a DVD for sale for about $20, but he sent me an email with some pictures and some details of the "plumbing".

from email:

Here are a few photos of the bronze melter in action.
The fuel is garden path wood chips.
You can see the high pressure air line 1/4" copper.
The ejector/aspirator is made from 1/4" copper tubing fused shut on the end. Insert a wire to measure the depth of the clear passage. Drill out 1/8mpt X1/4 compression the fitting nut and collet 17/64" so that 1/4" tubing can slip through the fitting. Grind the end of the closed tube to fit thru the drilled out compression fitting. Drill a very small hole 0.010" or #80 drill into the wall of the tubing near the tip with the hole at right angles to the tubing. Braze or weld a 1/8 fpt coupling at right angles to the gas inlet pipe just opposite the combustion air inlet so you can observe and remove any clinker deposits through the combustion air inlet. Drill thru into the gas inlet pipe. Install the drilled out compression fitting. Insert the copper ejector so the hole is at the centerline of the gas inlet pointing into the burner. 150 psi air will give you a good suction. You can also introduce propane instead through the ejector. Fine tune your alignment for best suction.
see photos

Then I emailed the Youtube video guy, and am currently waiting for pictures of the inside of his set up for the baffle, and what the superheating of air looks like. He is quite busy, back and forth from China and Indonesia setting up manufacturing of his stoves. I will post them when I receive them.

I currently have a large assortment of large food cans for my to be burner. I have a 20 gal drum already cut for my furnace, but as I can't afford the commercial 3k refractory, I'm going to make a small one out of 2 of the food cans with furnace cement/perlite just to do some small melts. Would have already started, but I'm waiting on the pics from youtube guy, and I keep forgetting to go get the refrigerator air compressor from a friend of mine. And I still have a problem figuring out how to adjust the updraft, can't really tell from the pics.

Hope that my post will help someone, Will be posting my pictures of set up when completed, probably on one of the casting sites, but will link here too.





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Hi babuga, and thanks for making contact with Das! I figured that would be a dead end, as old as the page is (Nov 5, 01).

Interesting that three of the pix show a lid (with no apparent holes) on the chip hopper. I thought that was supposed to be open for downdraft air. Whatever he's doing it's obviously working, I may have to get his CD.

The chips are similar to what I use now, but I'm thinking about a homeowner chipper for making chips. Right now I'm slicing logs into 3-4" discs and chopping those up with a hand axe.

So far I have a section of 6" stove pipe with an elbow at the bottom. There is a cap on the elbow for ash cleanout, and a cap at the top that I've made a hole in and inserted a piece of 3" stove pipe. I made a baffle to go around the lower end of the 3" pipe, to locate and seal it within the 6" pipe. There is a 1 1/2" hole in it for combustion air, which I need to make a valve for. In the bottom of the 3" pipe I stuck a stainless drain grate, and dropped a flared piece of 2.5" ID exhaust pipe for a throat (mainly to keep the fire away from the thin tin pipe). I built a box around an old microwave blower for an air supply.

I need to make a stand to hold it up, air valves for the blower and baffle, and holes for combustion air. And, of course, some sort of oven to hold the heat. It's pretty nice outside (60* morning in mid March!) but we're supposed to get a good storm today (the wind is starting up). I've been procrastinating on the internal air valve, but I think the simplest thing to do is roll a tin cone and attach it to a coat hanger so I can adjust how far it drops into the hole.

Good Luck!

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there was one time i was really frustrated because my forge wasent heating up after an hour so i got really irrated in just threw aluminum chunks in to it thinking it would put it out but it just made a big monstrus fire and worked fine but verry sputtery(dumb idea DO NOT TRY THIS AS IT MAY RUIN YOUR FORGE)

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AFAIK, aluminum doesn't burn. Magnesium is used in road flares...

Good Luck!

Actually al burns quite well but the oxide doesn't burn at all, makes good refractories in fact. To get al to burn you have to prevent the oxides from forming. There are chemicals that will do it and it's fun to watch water disolve al like you dipped it in concentrated HCL. Lets it burn too.

No magnesium in road flares, FHWA (Federal Highway Administration) wouldn't tolerate the danger to the public and damage to roadways mag flares do. They're specialty items for underwater, airial, anti missle, etc. use.

Still, just tossing al in a forge isn't going to result in burning al. It was probably a mag/al alloy.

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I would point out that everything will "burn", provided its hot enough (though it might not be combustion so much as molecularatomic disassociation)

In the case of any metal oxide however it will "burn" when its forced to give up the oxygen, like in chemical looping combustion, which I guess makes it an oxidizing agent as opposed to a fuel, so the point can be argued. Of course the reverse is also true as in an Aluminothermic reaction where its a reducing agent.


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  • 3 weeks later...
  • 1 month later...

Well, I finally got my gasifier working but not quite forging heat yet. A couple more fixes and I think it will be good. The opening is too big and some cracks in the mud need patching. You can see them in the last pic, they set the box on fire... :o Earlier in the week I got the oven done and fired it up but the inside of the box started to char so I shut it down, and after it cooled I drilled some holes and added mud/perlite/straw for insulation. You can see some steam coming out where the plywood is slotted together in the first pic. There is also steam coming off the oven in the pic where I'm holding the iron. Hopefully it will get hotter when it's all dry.

I guess the lesson here is don't use a wooden box unless you leave lots of room for insulation - these things get HOT! I would have abandoned it but the air valve arrangement needs to pivot at just the right place to work smoothly. If I can figure a good way to do it I may move the gasifier to a metal cart a friend gave me.

I think my superficial velocity is a bit on the high side - there's never any ash in the bottom to clean out... :P

Good Luck!





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OK, Monday morning - a fresh week - and I decided to go for the metal cart. Well, after an examination of the cracks revealed a LOT of fixing was needed. Making the oven opening smaller might prove dicey too, best to redo it. Anyway, I tore the mud/straw out of the bottom and removed the gasifier. I was planning on inverting the outer tube to deliver air to the hot spot or lower, so more heat would be carried with the combustion air.

The 3" flue pipe was a mess! Above the throat I made from exhaust tubing it was discolored and wrinkled, which doesn't show up too well in the pics but it's pronounced. :o There were pieces of scale falling out from between the throat and pipe, so I knew the throat wasn't holding up either. Good thing I got in there and looked.

I went to Lowes and a couple specialized places, one had a piece of 3" stainless flue pipe for $31. I checked with a muffler shop and got a piece of used 3" stainless pipe for free. That's my kind of price. :)

The pics -

The 1/4" holes I drilled around the top of the inner tube for combustion air.

Discolored and wrinkled tube.

The old grate installation - you can see the bottom of the throat tube; the other end was flared to meet the 3" pipe.

The scale was .010 - .015" thick.

The air valve cone with coat hanger through it and looped at both ends to hold it.

Freebie cart with hole cut for gasifier. Turning the shell over pointed the air inlet away from the ash cleanout, works better here.

Freebie 3" stainless exhaust pipe.

Good Luck!

Edit: Without the 2 1/2" throat tube the area should increase 44% so the velocity will be a bit lower this time too.








Edited by BeaverDamForge
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  • 2 weeks later...

Okay, I installed the gasifier in the cart, holding it in place with wires. I insulated the bottom with mud/perlite/straw from the bottom of the other setup. I broke up the oven and reused it also, but I think I would have done better to get more perlite and use that. The ash/mud doesn't seem to insulate or hold together as well as perlite/mud. I had to add a layer of perlite/mud/straw to the top, the outside was getting pretty hot.

I found that after getting it started with the blower, it will maintain a gas flame with natural draft*. Inside the oven, with a full fuel load, the flame detaches and fills the oven for a few minutes. The iron is getting to a medium-to-light orange, at least as hot as I ever got with my wood/charcoal forge, so I'm satisfied for now. It uses less wood, and it's more convenient to start and heat up, but the dragon's breath is wicked!

Good Luck!

*edit: The natural draft flame isn't intense enough to forge with, but will keep it fairly hot if you have to stop and talk to someone. I don't leave the area with a fire going, of course.






Edited by BeaverDamForge
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