I have ported the valve passages and milled.060 off of the head to up the compression. These two mods alone will add about 3 horsepower. These Kohler engines are in high demand for garden pulling tractors as they are so dependable and can be souped up quite a bit. Lots of good info for rebuilding them at gardentractorpullingtips.com.
GC
As I think about how I can build this, I have some questions.
Assuming charcoal only, is there any reason to preheat the incoming air? The outgoing gases will need cooled so some of that heat could be used to preheat the air but that would mean I couldn’t use that nozzle opening to light the gasifier.
If the charcoal around the burn chamber is for insulation, could it be filled with ashes instead of leaving it fill up with charcoal?
My only experience now is with my simple fire, updraft and I get a pocket that needs poked to get the charcoal to settle back around the nozzle. Will switching to a down draft eliminate that need and only have to empty ashes that make it through the grate?
Also, in my simple fire, my last runs had some damp charcoal and I got a lot more condensed liquid in my filter and moisture on the lid when I refilled it. Is something like the WK gasifier uses to condense and separate that moisture from the hopper useful for this charcoal only down draft or should it (to a point) draw it through the hot burn chamber and convert to Hydrogen?
Thanks Garry. Mine is a B&S. I think Simplicity switched to Kohlers in their 3414 in 1978? Somewhere I came across a guy that laps the head and block with valve grinding compound on a piece of plate glass and eliminates the head gasket to up the compression.
No pre heating air is not necisary. We are not combatting moisture like a wood gasifier. Its almost the opposite. We add in water to cool the nozzle. The resulting steam processed is exothermic cooling the process down along with exit gases. If you are dropping water then you are adding too much water. If your fuel is wet and causing moisture, dont put wet fuel in your gasifier to begin with.
Dont over complicate it.
100 pound propane tanks are a bit harder to come by than the smaller ones so I’m trying to get my plan together before starting to cut.
This is what I’m thinking.
There could be changes depending on what I might find as far as an ash hatch and that opening could possibly be moved down an inch or two but the bottom of the tank is rounded.
The actual burn pipe depends on what I might find. It could extend an inch or two down into the ash chamber and the grate might extend it a little lower.
I haven’t decided if I will cut the top off and make it removable or maybe make a fill pipe like my simple fire has. Maybe both so I could access the inside to change/check on the nozzle but the nozzle could be on a plate that would be bolted on the side.
If I understand right, this should give me more than double the run time that my simple fire does. The burn chamber alone is about the same height as my simple fire and bigger diameter.
I can only burn maybe half the depth of the simple fire (from the top charcoal level to the nozzle) before it shuts itself down but that gives me around 2 hours run time.
Judging by the burnt paint, it looks like the hottest part is around 8 to 10 inches from the nozzle.
The way I imagine the bigger one to be, the nozzle to grate distance as I have it drawn should end up about the same.
Hi Brian,
I have this big roll of paper someone said I could have when we were cleaning out the basement of my church. Experience tells me that time spent making revision after revision on paper and cardboard saves time and grief when I’m cutting and welding.
Rindert
Made the first cut. Even though this tank had been previously used as an air tank and I put some Baking soda and vinegar inside for good luck, it’s always a little scary.
Still in the thinking stage but I found a washing machine tub that could be the ring to hold the burn tube. Not as thick as I was hoping to find but it will be covered with ashes or unused charcoal to insulate it and direct the usable charcoal into the tube.
The tube is an old stainless steel soda concentrate container. It’s about 8-1/4 inches diameter but pretty thin and not easy to weld or braze. Still hunting for a better option.
I cut the bottom of the propane tank off mostly to make it easier to build or repair. Still debating how it will go back together but have plenty to do before I need to worry about that.
I cut the tank running the generator with the simple fire gasifier and the mixed charcoal with the finer flakes and it worked good but an angle grinder isn’t much of a load.
Brian do you have any old steel car wheels lying around? You could use your propane tank as the whole unit by fitting the wheel rim inside the tank as an air jacket for nozzles.
You’ll want to find one that either drops right in with a small gap to weld, or one that if you cut a shoulder down will fit.
The inch sizes of car wheels is kind of Nominal, a 12" wheel is slightly larger than 12" at the bead seat edge.
A car rim would be good thick steel to affix your nozzles.
It’s in page 109 of this book:
I haven’t found the size wheel rim I need yet but haven’t given up yet.
Is this anything like you are suggesting? The wheel rim inside the tank leaving an air gap. I only plan on one nozzle and was hoping to use it as the lighting port.
This reminds me. How can the WK gasifier get away with conduit nozzles right on the burn tube? I assume we don’t do it that way with charcoal because the burn tube is often the tank itself and we want the fire further away from the side.
Might this work? Must be a good reason it won’t work like the burn tube would melt instead of melting a replacable nozzle.
WKs don’t necessarily use conduit as the nozzle, but the burn tubes are in excess of 1/4" thick.
As far as single nozzles go I’ve been twice bitten forever shy of them. Even my 5lb weighing super thick 2" nozzle for my truck looks like a dog chewed on it after a few miles. Bear in mind I’m talking a 4.3L engine so I’m sure your generator would have a much smaller demand.
Granted I didn’t run water drip or EGR, just moistened charcoal. In your stationary setup you could do that very easily. EGR will definitely preserve the nozzle but won’t add power like steam/water drip will.
Perhaps the increased surface area of the burn tube will help preserve your nozzle.
With that setup you could make a Double Flute downdraft without needing a ring of jets or an air jacket. Just have the flutes right at the level of the top of the burn tube.
Probably just trying to over complicate this again but, so far, I’m happy with the single flute nozzle in my simple fire. Seems to be holding up better than just a single open pipe.
I still have the hexaloy nozzle that I haven’t tried yet.
I will have to see what I end up with for this new down draft gasifier but a double flute might work. I can only guess but the heat should be spread out more with the same draw so it isn’t all concentrated on one spot of the nozzle. I did find a big, thick piece of pipe that’s about 12 inch diameter and really heavy. Bigger than I wanted but I might try it anyway. The dream of putting this on the lawn mower isn’t going to happen so this will probably be for the generator.
It’s going to rain all day today so probably not much gasifier work going to happen. I did fire up the simple fire last night and cut the top off my 100 pound tank and then emptied my filter and remade the gasket. I had just been using silicone and grease to seal it but got some stove rope now so hopefully that works without needing grease. Probably going to replace the planer shavings with fresh ones and thinking about putting some rocks or gravel in the bottom to keep the shavings from soaking up as much moisture since any condensed liquids now end up in that filter. The last fill of charcoal (with the small flakes) had been sitting outside and I got a good bit of moisture in that filter and less power from the generator. Couldn’t notice it when only using the grinder but the compressor was struggling to run.
I’m hoping this down draft can handle damper charcoal than the simple fire. I probably should have just thrown that pile of fine charcoal on the compost like I was going to but didn’t want to waste it. The fresher charcoal that I grind I will leave the flakes in and only separate the dust.
Next job for the generator is probably going to be welding and that takes everything my little generator can give which is why I wanted to clean out the filter and probably put fresh, Dry charcoal back in the simple fire.
Oh, by the way, I tried my charcoal grinder with a hand crank instead of the cordless drill. I think when I build the better hopper for it I will put a hand crank on it and stop using the drill or worry about rigging up a gear reduction and motor. Worked good and I could feel if I hit a brand or a nail or screw. Seemed to make less dust since I was spinning it slower but had more power to cut through the bigger pieces of hardwood charcoal.
Suggestion; when you have a fresh batch of charcoal don’t screen out the fines. Just put the mix of fines, some larger and some ground charcoal in the gasifier. A range of sizes will produce the same fuel density, and permeability as all ground charcoal. With experience you will be able to judge a good mix, and add more ground or lump or fines as needed.
Rindert
Thanks Rindert.
This post by Kristijan describes the engine grade charcoal I should be using.
My simple fire doesn’t have a good way to shake it (no grate) and with my filter attached shaking the whole thing isn’t easy but I did notice that after I run it and would poke a rod down into the charcoal the level would drop a lot which sounds exactly what he descibed. I burnt the fines and left the bigger stuff.
That whole thread has some good information. Like this sketch from Tone.
Along with that skech, Tone says:
the difference between the upward method and the downward method is that in the former, all the water vapor rises during the generated gas and travels towards the engine, the charcoal dries completely and it is necessary to add water, well, in the downward process, a moist atmosphere is created above, which presses down through the hot zone, the steam is well superheated above and the conversion process is guaranteed.
Brian,
Yup, you get it.
Just one more note: the fines from your tlud are much more valuable as fuel than the fines from your simple fire, because they contain less ash.
Rindert
Another cool, damp day so I made another batch of charcoal.
Dry wood helped. Very little smoke this time.
I needed to cut the bottom out of a washing machine tub.
This will still need some grinding to fit my tank. This is the first time I tried to cut a circle with the angle grinder.
Guess I got my money’s worth out of that cut off wheel.
Haven’t found the right burn chamber yet but this is kind of what I’m hoping to build.
The paint can is about 6-1/2 inch diameter and 7-1/2 inches high.
This was another option but I’m pretty sure it’s too small at about 4 inch inside diameter and 5-1/2 inches high. Too bad though, it’s pretty thick. I might try to use it as the ash clean out port.
Instead of waiting and hoping the perfect piece of pipe shows up I wonder if I could just build what I want out of what I have.
This really old tank has already provided the metal for some projects so I’m tempted to cut a piece out and pound it into a tube shape for my burn tube.
To make around an 8 inch diameter inside diameter it looks like I’d need about a 26 inch x 12 inch piece to make the burn tube I want.
Nice thought but…
A little too far gone.
Oh well, guess I’ll keep waiting for the right chunk of metal to appear.
I hope everyone isn’t getting tired of my posting all my crazy ideas while I try to build this gasifier. I’m trying to post the process I’m going through (good and bad) instead of just waiting till I have a working gasifier and edit out all the problems and mistakes along the way.
I’m trying to design this so, when it doesn’t work right, I can easily take it back apart to make changes. I’m also trying to do it with what I have available. I have way more time than money so can’t go buy everything I’d like to use.
This is my idea for a fixed grate. It will likely get plugged up but might do as a test. I can always pull it back apart, cut out the bottom, and add a movable grate later if it actually produces usable gas.
A lot of mass here that might cause problems or make it take a while to get hot enough to produce good gas but it all comes back apart so nothing is permanent.
Smaller than I wanted but it’s what I had. About 5 inch inside diameter.
About 8-1/2 to 9-1/2 inches from the top of the stack of brake rotors to the grate depending on how I stack them which is a little higher than Giorgio’s version but smaller diameter.
The nozzle will probably be a little higher and removable so I can get these back out when it doesn’t work. The whole stack will be covered with ashes to insulate it and seal the spaces around them.
This was a sketch I made last night. Not exactly how I will probably build it though. Hopefully there isn’t much condensed liquids so the drain from the condenser could probably just be a plug in the lowest point.
The way my filter from the simple fire is made I used the original threaded opening for the propane valve as the drain. It only catches a tablespoon or so of liquid depending on how damp my charcoal is.
This hasn’t been tested yet. I filled the bottom of the filter with gravel. My thought is this will help condense any moisture that the gas contains and keeps my planer shavings from sitting in that liquid. Obviously, using dry charcoal in the simple fire should eliminate most of the moisture problem and hopefully the down draft won’t have as much problems with less than ideal fuel.
I could change my design and just try the stainless steel tube but it’s really thin metal but bigger diameter.
In the grate plate you need a lot more holes so it does not plug up. All the rotors will take time to heat up but will hold the temp inside and give you a good turn down ratio. But this is need in gasifiers that are not stationary and are not run at a constant velocities like running a vehicle engine. This will will be running a generator right. Some sort of a cone will be need to funnel the Charcoal into the smaller fire tube from the hopper, I like 60%. It should work if it is sealed up air/gas tight.
Thank Bob. There’s still a lot left to do so I’m sure this isn’t the final design. I’ll probably make an actual grate of some kind or at least cut the holes bigger in the fixed one.
Yes, my plan is to use this to run a generator. It’s going to be too big and too heavy to easily move around especially if I stick with the stack of brake rotors.
I was hoping I could just stack/compress ashes to make the cone funnel but I suppose that would be above the main heat so sheet metal should be good enough.
I welded the bottom in the lower section and then I welded the two sections back together.
This was easier than trying to make it attach together with gaskets and bolts.
It won’t be real easy but I can reach in from the top to put in the brake rotors or whatever becomes the burn tube.
If you can I would put a grate in that will hang by chains, then you can reach in through the clean out hatch and give it a bump or shake to clear the ash off the grate and out of the fire tube or linkers that might form above the grate. Leave 1" to 1 1/2" of space above the grate to the bottomof the fire tube. Make your grate larger than the opening of the fire tube by at least 2" in diameter. If the grate plugs up the gases can still go out the side of the Charcoal pile. This is great for a standing gasifier stationary unit. Some people put grate shakes on their units. I have never put any on my Charcoal gasifiers.
