There was a better one that they a much more controlled burn, I cant find it now.
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Solid grate bad idea on a sawdust gasifier. Variable grates to handle shavings, finer or coarser sawdust etc. Need to contain the material just enough to make gas while allowing ash to flow through. All âsawdustâ is not created equal ;~)
Logs bad idea because of particle size. Run a small city on cordwood sized particles ;~) That is a generalization. But you really have to know what you are doing to power a small ic engine on cordwood size wood unless you want to waste most of the energy in the wood which makes it impractical.
Time machine ârange fuelsâ for more info. DOE gave them a $76 million grant to make logs work and they didnât make it work ;~)
According to Raymond, sawdust gasification began as stoves. The poor Germans that worked at the sawmill were allowed to take sawdust home with them. Those in need figured it out from there.
If you can design a natural draft stove that operates cleanly on sawdust you can start figuring out how to make engine grade fuel from sawdust. IMHO a sawdust stove is likely the best first step to begin the learning curve.
Great thing about sawdust gasifiers is startup time. Because of particle size, very fast startup with a good design. Raymonds S-80 is usually good to go in 30 seconds to 2 minutes depending upon how it is bedded down after last run.
Totally agree with starting with a simple fire if you just want to run a small ic engine on natures finest. If you canât do that, biomass gasification may not be your bag. In my experience there are some that sincerely want to, but still canât do that. They donât need to launch out into the more complex. They need to absorb the fundamentals. Like Wayne sez, it is like riding a bicycle. Start out with a tricycle or at least training wheels and see if it is for you. Donât launch out into the complex if you have not yet figured out the simple.
All the best!
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Hi Doug,
I think you missed some things in my conception of the logs. What I was trying to relay is there would be a grinder turning those logs into dust pre gasifier. But on the fly and on demand.
On the solid grate, what I mean is there is no holes in the core of it. However it has cut outs along its perimeter to allow the char ash to fall through. This is a cross draft grate like on my commercial units and this will be automated. But you could be right we may still need to add holes but can be adopted later. Once the gas exits the down tube it then is updraft this will keep the char bed loose and flowing all while containing it better.
So just wanted to clarify on those features. Cheers!
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Hey Matt, all the best. Have long wanted to build a wind powered pencil sharpener that would âsharpenâ up to 6" diameter and make nice long shavings that would dry quickly. Lots of wood trunks in 2" to 6" range that would be better gone around here. Wind blowin darn well around here right now.
The equation, just like for fossil fuels, is energy in v energy out. In my book chunkers pencil out well in that equation for waste sized trees (thinnings) vs grinding/chipping.
Based upon Raymonds design would add holes in other than the perimeter and make allowance for sliding in different grates for different fuel particle sizes. Hope am not giving away too much of his hard won intellectual property ;~)
One more thing about Raymonds sawdust gasifier. Super fine particles tend to âdomeâ rather than flow. We would get really good gas for several minutes then the engine would stall. Open the hopper, poke the dome down, go again for another several minutes.
This could be overcome with exhaust gas return to bust the dome apart while engine is running IMHO but have not got around to trying it.
Thanks and cheers back to ya!
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Let me lay out my thinking a bit here. At the small scale chunks dont really work all that well and require a larger sized unit, adding cost weight and complexity. (Air Preheat, hopper agitators, hopper moisture management systems etc. and then all the sorting and drying processes) If I can make dust to work as well as my pellet systems and dust is really the only option that could possibly work in my reactors. (not shown here) Than making the logs into dust would be the best option for me. My reactors dont have all those issues, the hopper remains dry and void most combustion gases. The fuel stays dry and has reversed the issues that plague most other technologies.
This reactor system has cut out a lot of build cost and complexity. Only draw back is they require pellet fuels. This is fine for me as I wont go forward as a business with out a fuel standard in place; pellets fit that bill. Pellets also offer higher energy density pr volume, my clients want the machine to run as long as possible with out need for reloading and fiddling with units all the time. Auger feeds and other solutions just add more complexity, cost and time.
But like the man that got all this going. If we can get straight up fire wood to work as a direct input and the machine does all the work on the fly and on its own. Thats a game changer.
So again all this is just conceptual and rough drafts. If I have time will build this and update all. 
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Thanks for the video Matt. I suppose the sand particles just provide a whole bunch of ignition sources? New tech to me.
Rindert
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Yeah its pretty interesting. there was one that they lit the gas at the top. But I cant see this working for an engine but maybe for heating.
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Hi DougB.
Totally agree with your statements.
On raw logs-to-fuels Stephen Abaddessa wrote and published a DOE study paper on the energy-economics of chipped fuels versus further fuel-conversions.
Whole log chipping worked. A-n-y-t-h-i-n-g else done from there actually used more energies in conversions that could be end net produced.
So . . . another seeming âgreat ideaâ that would be actually fossil coal and oil energy subsidized.
And this is confirmed by Swedish and Finnish governments energy studied too. As NOT oil and coal countries they cannot afford energy dark holes. They cannot afford to waste away their current Nuclear and Hydro on net loss ideals.
Wood fuel pellets made-from-already-made wood wastes works. The energy cost to make them has already been passed on in the higher value products made from the wood logs.
Another missed point is back to your; there is sawdust, and there is sawdust. ANY sawdust appropriate is already committed to making higher value MDF (medium density fiberboard), and HDF (high density fiberboard) flooring and cabinet materials.
Just like the once pay-to-dispose commercial kitchens used cooking oils . . . . show a usage demand and it becomes a fought over must-pay-for income stream for somebody.
Live and learn from these easily found past âevolutionsâ; or learn again and again at your own crying losses in $'s and lifetime)
Steve unruh
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Hi Steve, I agree with you both as far as the processes weighed against one an other by themselves. However are you factoring this for gasification and the waste that you are going to throw away. Depending on the chipper, you are going to end up only a percentage. The bigger the chipper the bigger the feed stock = more usable chips. My Step Dads chipper gobbles up 16" diameter trees. But this just is not going to be the norm for most and with a small chipper you will be lucky to get 25% - 50% usable chips. This is what Im getting at. Verses if you ground this same volume and pelletized you would get nearly 100% of that yield. Yes pelleting comes with additional energy in, but is it really an added process? If you are no longer sorting the fuel isnt this replacing that process? Part of the drying process also a big part of pelleting.
Just trying to bring some points I think are valid. I will build this processing system If I have to eat crow, I will eat it with a smile
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Pelletmaking 1kWh-10 kg pellets
From wood to sawdust is the same 1kWh-10 dust. You start with a chipper, then a grinder and so on.
if you use green/fresh wood, you need energy for drying.
Energy in one kilo wood, either logs or dust is 4 kWh. So, if you don t use a waste material, you are throwing 50 % of the potential energy in wood away. And then you start gasifyingâŚ
How nice would it be if you can run on sawdust-waste?
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Not meaning too interupt your conversation with MATT RIDER. The biggest problem would be for transportation, being sawdust is so light it would take the hole bed of the truck too go 50 miles if your auger wasent too big and could actually get too the sawdust too push it too the hopper, could work for stationary at best. only if it was free sawdust. saw dust too me is harder too work with than wood chunking exersize.
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Ultimately, I will build all this process directly onto the machine. The user will just load cut split fire wood into the hopper. The machine will automate the full process. feed the logs into a grinder, the pellet press on demand. This will be a very slow process requiring very little energy input for this process. All it has to do is keep up with the machine and produce from 6 lbs up to 15 lbs pr hour max. This will have a hydraulic press.
Another version eliminates the grinder and you just dumps chips into it. The press will cut through them. Not sure if that will work or not but machines that do this exist.
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That woodchunker topic of Jan is super. Look how clean and simple everything funtions, top.
And sorry, my calculations above are not correct, you donât lose 50%. It is much less, but anyway. Imho you lose way to much energy, but most of all: it is just almost impossible to make pellets on a small scale. From the financial/time perspective. As Steve says, from an energy point of view it is undesired.
And yes, sawdust is light and maybe not for transportation. I wonât argue that.
First, I am reading. And that can stay for a while until everything is understood. Then maybe a stationary solution. Only if it can be succesfull, trouble free operation.
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Joep, you are basically like my typical customer. They dont want to make fuel, they dont want to the run the machine, they want it to run 24 hours with out any intervention. All they want to do is put fuel in it and push a button and it works.
Even if those processes require more machine energy input, there is still user energy input. This is the part we want to eliminate
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Yes, that is right. If you wouls sell a gasifier that runs on sawdust, we would have a deal. If I want it clean and easy, I will buy a generator and pour diesel in it.
Sorry Matt, only trying to protect you from the same mistake I made. But try and you know it is a dead end. From different points of view.
If you were living near my place you could pick it up and try for yourself. We were cleaning out everything and then I saw the installation again. Had a lot of fun with it, I know I can now, but there are better ways to spend energy, money and time.
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Impossible, start to read in about pelletmaking
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You say pellots on demand is good i agree if your gasifier cans are smaller more effient units, what about sawdust on demand instead, would there be a gain from burning wood chunks.
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Right, nobody wants to do âgrunt workâ. So the whole wood fuel thing doesnât work.
But maybe a sawmill would buy a system that used sawdust, because then they will have to do less âgrunt workâ handling sawdust. Itâs all about reducing âgrunt workâ. If you can do that they will pay you.
Rindert
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Its still easier than the other methods. You have to chip nearly four times the volume to produce that same equivalent in pellets. Nobody can seem to wrap their head around that. Your only chipping 25% of you would otherwise. Sorting chips is time consuming its a lot of work and so is drying the fuel. Unless your good with a small hopper that you are going to need to refill a lot than chunks would be a good solution. But bulk feeding is easier said than done.
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Yup Im not ruling out going with straight up saw dust. But I still see an issue with energy density and run times. Trying to keep em compact and cost effective to produce it all adds up.
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