[Gasification] Fuel, sizes........

Julia Hasty julia.hasty at gmail.com
Sun Nov 28 17:10:39 CST 2010


On Sun, Nov 28, 2010 at 7:09 AM, Greg Manning <a31ford at gmail.com> wrote:

>  OK, First off, Greetings List(s)!
>
> Second:
>
>  Since my accidental discovery of smaller feedstock sizes about a week ago,
> I've been doing some tests (ok, mad scientist stuff), to the acceptable
> "Minimum" size level in my downdraft units.
>
>  For those that do not know me, briefly, I build smaller downdraft
> gasifiers (under 250KwT) I do NOT go bigger than that, I have my reasons.
>
> I've been using a "standard" sized woodchip, typical of most small
> industrial units (NOT your home "shredder/mulchers") generally 15-30 hp
> units.
>
> These chippers produce, for the most part, chips about 3 x 3 x 0.25 cm
> chips (3/4 x 3/4 x 3/16") and down to the point of dirt, or mash.
>
> 6 - 7 years ago, I had settled on a rotary screen design using a "fines"
> screen of  0.63 x 0.63 cm  (1/4 x 1/4") square openings. this has been my
> "smaller" size since then. (Until this week, we have always discarded
> anything that was considered "fines", used these as mulch or horse bedding).
>
> Upon the somewhat accidental use of a fines pile as feedstock, much to my
> surprise, the unit accepted the fines for the most part, for about 8 hours
> of operation, (these where raw fines, directly from under the rotary drum),
> Yes the gasifier did eventually plug up and shut down BUT, not knowing what
> was going on at the time (I did NOT know the unit was running on fines) I
> was perplexed as to what had caused the problem, upon investigation, and
> finding that the worker had inadvertently used this pile, instead of the
> correct one, and finding out the length of the time the unit had ran on
> them, I undertook the new question of "how small I can go" in feedstock
> sizes.
>
> As it turns out, the unit will run consistently on a much smaller chip size
> than originally thought. We have since changed the fines screen in the
> rotary screener to 3/16" round holes (punched panel) on an offset pattern
> (68% opening) the ratio change is as follows:
>
>  Original 1/4 x 14" square openings, ratio of fines to acceptable feedstock
> 30% fines, 70% feedstock
>
>  New  3/16" round openings, 10 - 13% fines, 87 - 90% acceptable.
>
> Hoping that this information is useful to someone.
> Kindest regards:
>
> Greg Manning,
> Canadian Gasifier Ltd.  (www.cangas.ca)
> Building Hi-Performance Gasifiers, Since 2001
>
> Brandon, Manitoba, Canada
> 1 (204) 726-1851
>
>
>
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