What Krstijan said. I didn’t want to mention it because I didn’t want to pretend that I knew what I was talking about. His explanation was exactly right.
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That picture was mainly to show the biggest pieces that now make it through the grinder. The screen in that picture is slightly bigger than 1/8 inch (4.5mm) so I do get a mix of sizes as well as the small biochar size.
This is an example of what gets 'thrown away" as biochar. I questioned if I should be saving this as engine fuel and it seemed that most people were only saving the 1/4" + pieces as engine grade and anything smaller was biochar. The very finest dust had been separated from that biochar in the above picture using a window screen.
This is a view inside the simple fire right now. There is a wide range of sizes.
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Those little flakes are great for engine grade charcoal. I only sift out the extra fine dust like Kristijan said.
Gary Gilmore used to suggest a range of 1/8" to 3/4", mostly because it’s not too hard to find hardware cloth in those sizes and it’s the same size range that Swedes used for their early updrafts and the Kalle charcoal gasifier.
Downdrafts can tolerate a bigger size, some vehicles that used the Mako gasifier ran an average 20mm-60mm size.
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Thanks Cody. I seem to get conflicting opinions about the smaller size flakes so I’ve dumped a lot of that size flakes into the compost pile.
I questioned if I should be saving it and I thought I was told not to use it. I thought some people said that 1/8 inch was too small and their smallest size was 1/4 inch.
I have mixed some of it into my engine grade fuel and it didn’t seem to hurt anything. I’ve also fed some of it back into the nozzle as it was running but couldn’t notice any effect good or bad.
It will give me more fuel if I only separate the finest dust so might help keep the gas cooler. If nothing else, it will be a lot less wasted charcoal.
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Brian the only reason dust goes into the bio pile is because it can block the flow of gas when it compacts hard against larger pieces , those flakes as you call them will make excellent engine grade if its mixed in with the larger charcoal from your first photo , as mentioned before keep your eyes out for a petrol driven wood chipper/ mulcher the type with hammers in it , take the engine off and replace with a wheel chair dc motor and you will have the perfect charcoal grinding machine . like the one i posted a while back , i have now decided to give it a service after sitting outside in all weathers it was looking real sad so a coat of paint and a new steel table for it to sit on and a new Shute for letting dust fall out and a new belt its working better than ever before .
Dave
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After a few runs just refilling the simple fire without actually cleaning it out I figured it was time to dump it out and check on the nozzle again.
I’d guess this is after 4 or 5 hours total run time but might have been a bit longer.
Sometimes I’ll shut off the generator. Open the simple fire. Poke the charcoal down and refill it. Then restart the generator and keep running.
My last run was very hot at the end which is part of the reason I figured I should check on the nozzle.
The slag did need broken off the nozzle but the flute nozzle itself is holding up pretty good. Won’t last forever but not getting shorter each run like just the straight pipe I started with did.
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This was the only reason i could not carry on using the flute nozzle on my large 55 gal gasifier after maybe half dozen runs it was getting harder and harder to light or to poke the holes clear of slag ,and it was a real pain in the ass to empty out ,oh and bloody messy too !
But on build your size i think its a real winner easy fast clean outs for sure .
Dave
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Emptying out the charcoal from my simple fire is still a dirty job but easy especially if I do it with most of the charcoal used up.
I tried poking up through the holes and it helps but it does keep getting harder to light so I need to empty it and get the slag cleaned off after 3 or 4 hour or two runs.
I still have the Hexoloy carbide piece that I haven’t used yet but this flute nozzle is working good enough I’ll probably just build another one like it when it does finally wear out.
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I clean out my shop vac and then suck the charcoal out before screening and reusing it. Not a dirty job that way.
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These filter saver bags help save the pleated paper and make filter cleaning easier, even if more frequent.
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That’s a great idea Bruce is this something you made up or do they sell things like that ? what is the material is it micro fiber ?
Dave
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They are made by several different companies. Amazon lists them as “vac filter retainer cover”, but you could make your own out of an old wool sweater or blanket.
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