Harry Home owner Bio-Mizer Sawdust Dryer.

[Jeff]

With sand, your drying the exterior of the particles, with sawdust, you are trying to dry the interior. Not to say it won't work, it might. But there would be quite a difference.

Things to take into consideration is that you have to aquire the sawdust, load the sawdust in the dryer, remove the sawdust from the dryer, repackage the dust for storage. All lots of added steps. The perfect solution would be a dryer that feeds directly into the bio-mizer and can dry at the same rate that the bio-mizer will consume.

[Radar67]

From the posts on the forum, the Bio mizer would produce enough extra heat to heat a tunnel or chamber so to speak.

At ground level, have a hopper to load the "wet" sawdust into. At the bottom of the hopper, a conveyor (similar to firewood processors, but smaller) catches the dust as it gravity feeds out of the hopper. The conveyor runs through the chamber (a piece of galvanized culvert maybe) to the Bio Mizer hopper. The heat in the chamber dries the dust (thickness could be controled by limiting the height of drop from the wet hopper) as it passes through on the conveyor.

[beenthere]

I'm thinking about investing in one of those hand held gas powered leaf blower/vacuums that will suck up leaves and mulch them and bag them.  Menards has one on sale for $119. If they mulch small enough they will burn in the Bio-Mizer.  Worth a shot as many leafs as I have.
..........

I'd suggest seeing one "in action" before investing the bucks. Or be sure you can return it used. But, a good experiment to learn more may be worth it. 

I doubt it will do much to a leaf, other than beat it up a bit.

Was one on craigslist the other day for $15. Had set for a year and he couldn't get it started. 

[Jeff]

This mulcher is supposed to be a 10 to 1 reduction in volume. Were talking dry leaves.

[DanG]

My Dad and I used to grind oak leaves for the gardens with an old mulcher/chipper with about a 5hp engine on it.  It would take about 3 trips through that to get it fine enough for the Biomizer.

I like Zopi and Radar's ideas on using the Biomizer itself for the heat source.  You would need to keep the sawdust moving, like in the tumbler, with hot air blowing through it to dry it efficiently, I would think.

[beenthere]

Maybe a vertical auger raising the sawdust up a round column that has heated from the BioMizer, and controlled-blown air across the top that would separate the light/dry sawdust particles to a collector such that they'd then drop down to the auger feeding the BioMizer. That wetter sawdust which doesn't blow off into the burn bin, would fall back to the hopper to be augered again up the heated column. Continuous separator of sorts. 

Sounds a bit nuts...but 

[Jeff]

Hmmm...

Only to have a fab shop at ones disposal.

[DanG]

Beenthere, if that is nuts, then I'm nuts.  I had just concieved of that same concept, and was about to post it.  Nutty minds think alike, eh?

[Jeff]

Several things would need to be dealt with, a few that are still problems with simply feeding sawdust as a fuel.   

Sawdust bridging in a dryer for starters. You would need a way to keep the sawdust moving and entering the auger. You don't have gravity working for you if the sawdust is being elevated.

I'm not trying to shoot ideas down, I hope I'm not sounding negative. I'm trying to beat out the possible glitches.

[Ron Wenrich]

I had a client that used to dry shavings with heat lamps.  It works for McDonald's to keep those cheap hamburgers warm, why not sawdust?

My client's process was to put it on a small conveyor.  He had 3 heat lamps about 6-12" above the belt .  He also put wire across to flip the shavings.  Total process time was less than a minute, and he bagged the shavings.  If the moisture content would have been too high, they would have turned moldy.  

If you could move the sawdust in a thin enough layer, heat lamps should be enough to get it to dry.  A vibrating conveyor would do the trick, but the cost thing probably gets in the way.

[Jeff]

Yea, thats the thing. Ya gotta think the heat lamps suck the juice, then the energy expended in running the mechanisms of the process.  I guess some experiments would be needed to see just what exactly does it take to remove the moisture. 

My wish would be for a passive system. Something that dries the dust on its natural route through the storage hopper to be burned using the energy of the bio-mizer.

[Ron Wenrich]

The best I can come up with is to spread it out on black plastic, and cover with a piece of black plastic.  Passive, low cost.  Might even get a tax credit for going with a solar dryer.   

[Jeff]

Ron, Where would the moisture go?

[Ron Wenrich]

So, poke some holes in the top.  Or make a rack and frame to give a little bit of clearance and to support the plastic.  You'll be surprised at how hot that will get.

[Jeff]

I wonder if an auger and its housing were both heated how far the sawdust would have to move to have the moisture "fried" out of it.

The sawdust I am using now came from member Barnie Geer's farm. I'm at the end of that supply now.  This dust is dry dry dry. If you don't wear a mask when shoveling it, you got problems.  It got that was from being in an older barn, on a wood floor for what was probably years. I dont know the time frame for sure. It was conveyed into the barn to be used as bedding, but never was. The floor it is on was over the stalls, so it also had air flow under the pile.  The barn is well ventilated as old barns tend to be, and its out in open country where it gets lots of air.  That "system" produced the absolutely perfect fuel.

[Tim L]

use a corrugated plastic culvert spinning with a fan at the end .

[stonebroke]

You should use the waste heat off the exhaust(chimmey) of the bio mizer. If you put in a rotary tumbler and blew the exhaust gases though the middle of it it should work . You would have to be careful not to set the sawdust on fire in the dryer.

Stonebroke

[Jeff]

To dangerous without using all sorts of spark arresting technology.

[rbarshaw]

Use a pipe in a pipe, heat the space between the two pipes from the bio-Mizer, run an auger thru the inside of the pipe to move sawdust, heat it, and drive off the moisture. Set the whole thing at an angle and control the auger speed to allow the dust time to dry, have it open at each end to allow air to carry off the moisture.

[Brucer]

Many years ago, I did this kind of stuff for a living. Memory isn't what it used to be, but here goes ...

The secret to drying surfaces and small particles quickly is to move a lot of relatively dry air over them. Simply heating them isn't very effective. Most efficient is to have the particles going in one direction and the air going in the opposite direction.

A good way to get dry air is to start with cold (or cool) air and heat it up. That lowers the relative humidity.

Ideally, then, you'd have your sawdust falling through a column of slowly rising warm air. The air would start off cold (outdoor air in the fall and winter) and would be heated slightly before it entered the column.

Using stack gases from the biomizer itself isn't great because the combustion process generates moisture. Worse yet, any moisture remaining in the sawdust entering the biomizer will also show up in the stack gases.

Before building a lot of complicated apparatus, how about this simple experiment. Park your sawdust-filled truck into a heated building. Vacuum the sawdust out of the truck, using a simple cyclone collector between the vacuum machine and the nozzle.

The cyclone is nothing more than a special lid that sits on top of a garbage can or 45 gallon drum. Incoming vacuum hose enters on one side of the lid, pointing almost horizontal. Outgoing vacuum hose comes out the centre of the lid, pointing straight up, then connects to a shop dust collector (or a large shop-vac). The garbage can collects 95% of the dust.

You can buy the lids commercially (Lee Valley Tools sells 'em) for $50 or so ("cyclone lid", part number 05J30.01, check it out on their web site for a picture). You should be able to cobble one together with a plastic garbage can lid, an extra vacuum hose, and some duct tape.

The drawback of this system is that your sawdust and warm air are flowing in the same direction, so it won't be as efficient as it could be. The advantage (if it works) is that material handling is pretty simple. Vacuum out your truck and collect the (hopefully) dryer sawdust in a garbage can. It's also cheap and simple to test.