[Gasification] Why dry gasification fuel?

[Greg Manning]

 Sorry Steve, it is C.....

it's not pyrolysis that is the concern, rather the area farther down the
reactor, we call this the "Reduction Zone" (zones from the top down, hopper
(Bunker),  Pyrolysis, Oxidation, Reduction). side note: reduction being
chemical NOT physical.

Here, this will be a bit of reading... BUT, for the condensed version, go to
section 2.5.1 Processes occurring in a downdraught gasifier (About the
internal workings), This "Net Book" is so to speak... my bible....
http://www.fao.org/docrep/t0512e/t0512e00.htm


As far as process heat, the screen cased auger, has air from the gas output
section condenser, piped to it (about 50c or so)

Greg

BTW (By The Way) Downdraft gasifiers use charcoal as insulation, as to not
melt the steel casing within the oxidation section (where we get our needed
heat, for thermalitic chemical reduction).



-----Original Message-----
From: gasification-bounces at listserv.repp.org
[mailto:gasification-bounces at listserv.repp.org]On Behalf Of Steve Redmond
Sent: Friday, December 15, 2006 4:58 PM
To: gasification at listserv.repp.org
Subject: [Gasification] Why dry gassification fuel?


Hi Greg,

Yes I do subscribe now. No need to send twice.

I doubt that the 700 to 900 (F, I believe, not C) needed to thermally
sustain pyrolisis is unattainable with 50% mc chips in a self (charcoal)
consuming reactor.

In fact I'm certain it is attainable.

Excess heat and steam can be condensed from the gas flow and made to give up
heat to the reactor. The air intake is one area to look at.

In fact by drying chips with process heat, the energy balance is the same.
The question is, where do you want to spend your energy to
evaporate water from the chip, before pyrolisis or during it? No free rides.

I'm suggesting not separating these processes.

Unless naturally air dried chips are used, heat input to dry the chips comes
from the chips, at one stage or another. Even the engine exhaust manifold
heat derives from the chips. It also could raise reactor temperature, rather
than drying chips pre-pyrolisis.

The advantage is to eliminate a separate stage of chip handling: drying.

--Steve


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