[Gasification] Wood Chip classificaton

[Bruce Green]

Hi all, If you really want to dry something cheap use a greenhouse. See
this technology  http://www.parkson.com/products/thermo-system   . Bruce
Green

On Sat, Apr 14, 2012 at 2:25 PM, Luke Gardner <lgardner at wwest.net> wrote:

> Greg,
> I like it, there is certainly more than one way to skin a cat.
> I was leaning toward auguring up and out of a receiving hopper to a very
> slow moving and long declined trommel that has sections of screen to drop
> the fines out early on, and have airflow (salvaged heat) blown through the
> trommel opposite the flow of the wood to carry the moisture away.
> I would agree that the passive approach takes about a full day of good
> solar...  10 hours if the layer is thin enough.
> I found by scattering them on a tarp (for easy collection) that the top
> surface nearly "flashes"  off dry very quickly.  and then some hours later
> in  good summer sun,  if you pick a chip up it is dry on top and there will
> be condensation hanging out below it on the tarp, and its back will still
> be wet.  It's like they beg to be flipped over and placed somewhere else.
>  I believe that with minimal agitation (slow tumbling) in a thin migrating
> stream they could be dried rather quickly.
> anyone?
> Luke
>
>
>
> -----Original Message----- From: Greg Manning
> Sent: Saturday, April 14, 2012 5:23 AM
>
> To: Discussion of biomass pyrolysis and gasification
> Subject: Re: [Gasification] Wood Chip classificaton
>
> Good Morning All.
>
> This is getting interesting.
>
>
> I spoke with Pete a while back about this, and need to correct a
> statement I made to him.
>
> "correction the fines (under 3/16" bits) do need to be sifted out"
> this was about a statement I made to him on the phone, about this
> thread.
>
> As far as drying wood chips, 3 things I have found are:
>
> 1) Sifting the fines before storage (even green) does promote faster
> drying (this is relative as they still take a long time to dry).
>
> 2) The "top" about the first 2-3 inch layer of chips in a screened bin
> dry quite quickly (days) where as the stuff at the bottom NO drying
> action has taken place.
>
> 3) Removal of that "top layer" of dry chips to another area does
> indeed cause the next 3-4" layer to dry quickly as well, and so on if
> removed, as they dry.
>
> I've studied this problem in depth, and have a somewhat simple
> (ya-right) method of drying.
>
> Sun, I'm in the process of designing a "sun lift", where as chips are
> augured to an inclined day lift, the lift consists of  a wide belt (48
> inches) that is inclined on just slightly less than the angle of
> repose for the chips (about 30 degrees from horizontal), AND/OR, has
> ledges that a small thin layer of chips rest on. This lift is some 12
> feet tall, and once the chips reach the top they are captured in a
> covered trough that connects to a chute that sends them to a second
> storage area.
>
> Here's the thing, the lift is rain protected, and has a sheet of clear
> glass or plexiglass covering the area exposed to the sun.
>
> The process ONLY runs during warm sunny days, and at that, the chips
> entering the bottom take the entire day (10 hours) to reach the top.
>
> using a light meter sensor that only triggers the units operation once
> the sun gets to "X" brightness (cloudy days would not trigger the
> unit).
>
> Preliminary findings are that sample configurations of chips sitting
> as a thin layer on a sheet of plywood (with the 30 degree inclination)
> take about 6-7 hours to be "bone dry" in the sun with a small flow of
> air from the base upwards (chimney effect) I simply used a couple of
> 2x6's on the sides to support a plexiglass cover and a bathroom
> exhaust fan to provide the airflow.
>
> This was a test "mock-up" to simulate the slow moving "belt" system I
> am thinking of.
>
> the chips that where placed on the board in the morning where 45+%
> moisture green, a the end of the 7 hours, they where very "crisp" to
> the touch, and snapped with a loud "crack" (indication of being very
> dry) when pinched sideways, tested end of cycle moisture was under
> 13-15%. the layer was rough, but for the most part, I would say 2-1/2
> inches thick.
> extrapolation of the cost to do this is based on the following:
>
> 1/4 HP electric motor running for 10 hours a day at 10 cents a
> kilowatt (I pay less than that, but know that some areas pay more) MY
> sample motor under load uses 2.5 amps to work, therefore 2.5amps times
> 115 volts equals 288 watts/hour (VA's close enough) so say 4 hours
> costs 10 cents or 25 cents a day, times 31 equals $ 7.75 a month (
> I've rounded up on the costs, as to cover the cost of the bathroom
> vent fan also).
>
> Because the system runs so slowly the 1/4 hp motor (through two 60:1
> reduction units one feeding the other) should develop enough torque to
> run the belt and in-feed auger both. the output is gravity and I make
> the assumption that someone would check on the unit at least once
> every 2 days.
>
> Greg Manning
>
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