Yes, I will admit I am a self taught welder and not the best, I am a farmer and can weld for structural integrity, but they are not very pretty and I couldn’t guarantee that all of my welds are perfect or air tight, so to ensure the integrity of these critical welds (or as you said the potential for cracks due to dissimilar metals cast iron to mild steel) what I did was anywhere that I wasn’t positive would be airtight, once the welds cooled and I cleaned them, I liberally smeared high temp stove gasket cement all over the joints to make sure any crack or weld imperfection was sealed off that way. I didn’t get around to running my test today, but plan on it tomorrow morning, hopefully by this time tomorrow I have a good report for y’all.
And Wayne, I’m glad someone else feels my pain on the cow licks lol, no looking forward to this winter, I’m sure they will be going up like everything else!
Maybe a little OT, but talking about cast iron crack repair reminded me of the “Lock-N-Stitch” method:
Pete Stanaitis
You aren’t the only one. I do have the welding textbook and a whole series of welding books for reference.
And I should mention, the whole brake thing is more like a Mike LaRosa design. I do not know what happened to his plans or if there are pictures or discussion left, but I would search for as much info as you can. He was actually one of the first folks of this group who had something working. But he passed away a few years ago, and I don’t know if his stuff made it to this site or not.
I have some drawings of his uploaded. Mike used two same shaped drums bolted together.
First image is a doodle that Mike drew up, Mike didn’t have the opportunity to weld all the time to most of his stuff was either brazed or held together with high temp RTV. This design could work a lot better if welded together. The external jacket is actually for air. His lower barrel is the gas collection area. Mike would usually just weld the nozzle pipes into the hopper side of the gasifier and make an external air jacket. You can still find YouTube videos showcasing his gasifiers. Woodgas Show & Tell: Mike LaRosa's Chevy S-10 - YouTube
Second image is Tom Collins’ evolved design adapted from Mike LaRosa’s form factor. Tom is a really talented draft artist I think, this focuses just on the hearth area.
Well, another failed test today after all of my repairs/ modifications. I made some fabulous smoke, and it even looked like it was starting to clear up after a short while, but nothing that would ignite. As you can see from the picture below from what is left I seem to be getting good combustion, you can even see where the wood dropped down into the 3” choke area. I am thinking maybe I need to add more air nozzles and just figure out an airtight hopper lid. I think Wayne said that white ash is not a good sign and it looks like I have plenty of it - what does that mean?
Basically, I lit my char that I showed pictured in my other post, and then once I was sure I had that going strong, I added about 3” of the wood chunks to the top - (now new char pictured above). I did not fill the hopper all the way since I thought this would probably give it enough to run a test and then if the test failed (as it did unfortunately) it wouldn’t burn all day, but wold burn out quicker so I could not have as much to clean out if I need to do more rework.
The issue is that the air isn’t being controlled. With a FEMA there’s no shortage of air. You’ll have to use nozzles piped in from outside. Nozzles supply a controlled amount of higher velocity air to deliver a reaction at a fixed spot.
Also check your welds, use an air gun and some soapy water. Spray the soapy water on the welds and blow air from the opposite side. Make note of where any bubbles are coming from and weld over it.
If it’s somewhere outside of the gasifier that doesn’t get up to 600°F you can use Red Ultra High Temp RTV silicone, but if it gets that hot it’ll burn and the silicone will make it’s way to the engine and scratch the cylinder walls. Jakob North has had that experience and he’s sworn off of RTV near the hot parts.
Ok, good to know, thanks. So my next step is to redesign my hopper lid and get it airtight, since I know its clearly not. And then work something out for air nozzles. I had many misconceptions going into this and am still leaning as I go.
Derrick if you want to do a ring of nozzles and have a way to cut the steel, you can make a donut using some flat stock.
The ring doesn’t have to be very big, maybe 1" square, I’d just make it so it hugs the hopper wall but not so much it’s a pain to remove and install. Or make it as big as the lid diameter since that would be the bottleneck.
After that you just drill out some holes to weld the pipe nozzles into. With the restriction you have I’d say just 5 nozzles is plenty.
Or alternatively, take this idea of the steel donut, and put your nozzles in the hopper wall, and consider the hopper as the inside wall of the donut and then you will have an air jacket.
Or you can try a central nozzle. Make sure the tip end has pipe threads that you can get to for replacing the actual nozzle end. What I did is use a pipe that was threaded at both ends so I could take it out with a pipe wrench.
How much wood did you start with? Are you running that open top? If you are making fabulous smoke, you are pretty close,. It looks like there is char on top, and the air maybe coming from the top given you have a hole right down the center of the char bed or the fan is pulling too much air. (I have to go back to see what you are using for air.)
What does your flare look like? sometimes the flare design matters to get it to light.
He originally tried to make it no weld in part due to tool limitations, but he was also originally trying to make a Fema2 because the people who did Fema got a 100k research grant to put that together. Part of why he brazed is because he was using propane for his torch and that is all he had.
The second was a later iteration. I believe Tom said that was LaRosa’s grate design, and he was working on other parts like the airflow and heat exchange. Tom said it was tar free.
The video is a later generation, but I don’t think many changes were made to the basic hearth except the nozzles.
I added an annotation just because the drawing doesn’t make sense unless you have a clue what parts he was using. I -think- he originally used a water heater tank but he says he has well water pressure tanks in the last video.
I like the idea of using a sealed wheel as a plenum for the nozzles.
Tom I’ve used that idea twice now and I really like it. If you just cut away the spokes and leave the extra welded parts to the rim you have a little extra material to act as some mass.
Thanks Cody for the nozzle ideas and the video, I also like the idea of the wheel center but unfortunately with all the junk I’ve got lying around I haven’t been able to find anything that will fit either way too big or way too small.
Sean, I started out with about 2-3” of char in the reduction zone on top of the smaller choke, and then once I knew that was lit and would stay lit, I put probably another 3” of dry wood chucks on top. I didn’t fill the hopper to full capacity so it would burn out quicker if the test failed. I did not run with top wide open, but the top is not airtight by any imagination as I started out with the FEMA design and thought I needed to allow some airflow through the top. I’m going to make that sucker airtight and then experiment with some nozzles to control the airflow. Again, a lot of misconceptions and misunderstandings on my part.
We’re here to help others get a little liberty or enjoyment out of woodgas. Wether it be Power On Wood or Driving On Wood.
Otherwise we’d be like a bunch of wizards in an ivory tower talking about the same old stuff and getting nowhere.
i am not sure 3" is enough even if it is sealed. It is good to fire it up and look for leaks. I wasn’'t sure if it was finding a leak like the lid or there was enough air in the lid to do that.
A gasifier technically doesn’t -have- to be sealed at all. Part of the sealing is to have the absolute control over the airflow to the fire, and the other part is safety.
Cody, right now until I can figure out where I am gong wrong yall are like a bunch of wizards, lol - but yall are kind wizards! You don’t know how much I appreciate being able to come on here and ask questions, so I can figure out what my next step is.
Sean, yes, that is one of the things that has been confusing to me
That’s how I started out with the FEMA style, and I even saw one video where a guy had no top at all, but then I get advice to build nozzles and I ask, isn’t it getting enough oxygen through an unsealed or open top? But then it appears it has gotten too much or uncontrolled oxygen even with my smaller choke and sealed up ignition tube evidenced by all the white ash and so that’s why I have been working on sealing my top and although I have a couple of nozzles to conduct controlled oxygen to the hearth zone I will probably have to add more or re-configure with a center nozzle - my idea at this point is to control the oxygen flow completely by sealing the lid and having the ability to slow or cut off the airflow through the nozzles just so I can see what the heck it is doing. I am pretty sure everything is absolutely airtight since when I have a failed test, and I turn the blower off and shut it down the only place I can see smoke still coming out of is the hopper lid. So I figure on my next test, if it doesn’t work again, at least it may give me a better idea of a leak (if there is one that I have not found) if the lid is sealed.
Also you had asked me about my torch, here are a few pics - it is made of 3/4” iron pipe with about a 2” tube welded to the end. Here are the pics.
Hello Derrick, if you follow the posts on the construction of gasifiers, you can see that many people put a lot of effort and knowledge into creating a successful product. Let me give my opinion, the air must enter exclusively into the zone with coal, so the coal is gasified, and the heat radiates to all sides from this part, it creates the conditions for pyrolysis above, where water vapor and tar gas are produced, so it must not enter the upper part under any circumstances oxygen to come, but these gases must descend into the zone of glowing coal, where the coal converts them into clean gas. All the oxygen must be consumed in the hot coal, which I cannot say based on the construction of your nozzle, because the oxygen can also travel upwards and thus a combustible mixture is created, another problem I see in the construction of the hot zone, where the pyrolysis gases easily escape the conversion, the construction of this part must not allow this.
Imagine your gasifier as a closed container filled with wood, from which you suck out the generated gases, and the air enters through this pipe, what happens to the gases, what are the pressure conditions inside??? Hot gases force upwards, while colder ones fall downwards, you suck out the generated gases below and thus create a negative pressure in this part, or in your case the negative pressure is almost the same over the entire surface of the room, unlike the WK or Imbert system, where the negative pressure is greater in the fire hose. which makes it impossible for oxygen to spread upwards, it even happens here that the energy of radiation from this part is so strong that it causes a great expansion of the pyrolysis gases, which even means the formation of overpressure in the storage tank,… keep in mind the basics of thermodynamics and that all processes take place in the gaseous state.
That gasifier is looking for a source of oxygen even if it is shut down but still burning. Smoke won’t come out a pin hole under those conditions but air will get sucked in.
The world would be a better place if the F.E.M.A’s were never developed and promoted.
Every single endeavor beginning with a virtually open topped “Stratisfied Downdraft” concept failed to make good engine grade gas until they highly modified it.
From the India Institute of Science CGPL guys; Flash001USA and others down to Wayne Keith himself.
These needed modifications; follow the same pathways:
Seal up the top to get good system complete controlled air-in.
Put an actual restriction area to force the upper system produced gasses to ONLY go past a glowing charcoal bed.
Use zones setting up mid-lower system air nozzles to blow the system made charcoal up to good glowing conversion temperatures. (yes. I simplified this)
Sigh. The developers of the F.E.M.A. were Gov’Mint paid men. Thier later evolution of their systems concepts were large truck trailer sized units costing hundreds of thousands of dollars requiring screened woodchipped auger feeding. Needing multiple rings of air jets to follow their floating zones. Set up to be all computer controlled.
Can’t even say, “The Tail wagging the Dog” on Gov’Mint approach systems.
These always become the Seven Headed Hydra creations with heads competing and biting into themselves.
DerrickD, you made a gas can and some peripherals.
This is good. You are actually building, DOing, firing up. This is Better.
Falling down, skinning knees, and getting back up to do again; better next time, is always the very best of teachers.
Regards
Steve Unruh
The F.E.M.A. gasifier was designed to put a stop to people to actually getting into gasification by our government. Period. Gasification got a bad report from the F.E.M.A.gasifier. The oil companies have had our government in their back pocket for years and years. Bribbing oh I mean lobby the law makers to make laws to try to stop “We The People Of This Land” from doing gasification. We fought back.
Just look at all the well made gasifiers of WW2 and now we have better ones.
Oh yes it was for emergencies this gasifier was design. Yup. B.S. And it would ruin your emergency generator too that you needed.
All I can say is thank God Almighty, men didn’t stop trying and now we have some of the best gasifiers ever designed for today to use. More important they gave us the competed designs and we have them here on DOW.com.
Bob
Allow me some more thoughts, the “fire hose” of the WK system is the best thing you can install in a gasifier, it simultaneously preheats the air and keeps the metals at a moderate temperature and distributes the temperature over a longer area. If you use larger pieces of wood, the length of the pipe should be longer than the diameter, but if the pieces are smaller, the length can be the same as the diameter or even shorter, because everything goes faster and more densely. I thought a lot about the restriction plate or opening, is it even necessary? Now I can confirm that it is necessary, in the case of my production, it continues as a narrow fire hose for the gasification of fine coal and provides clean quality gas at low load.