Hybrid Car – More Fun with Less Gas

Wood Gas or Syngas Gasification of Bio-Mass - Page 4

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Posted by Curbie on October 23, 2009, 7:02 pm
 


Ulysses,


Me too!


To my understanding, all gasifiers require fuel with some
preprocessing the WWII type wants wants wood cubes .75x.75-2x2 inches
the prevent "bridging", so does the FEMA model, then there are the
pellet models that require palletized fuel like:
http://elevatorman.shawwebspace.ca/pages/view/


I agree, but it seem to me the net energy evaluation should be applied
to all forms of fuels for gasifiers in that for the WWII and FEMA
types you must first cut the three down, cut the tree in to logs,
transport the logs, split the logs, and then cut the splits into
cubes.

 This requires energy too human or powered, I'm not try to bad-mouth
or over-complicate the wood fuel preprocessing, but some since some
preprocessing energy seems required there too, I'm wondering if by
using algae as a annual feedstock how much energy for preprocess is
needed comparatively?

Just thinking out loud, it seems I could pump/pipe water/algae to a
juicer type centrifuge for separation and partial drying (it seems I
would have tree falling, logging, and transport energy equivalence for
this). Then press the separated algae into cubes or pellets (it seems
I would have splitting and cubing energy equivalence for this).


Some guys have all the luck, I'm not one of them.


I especially like the FEMA document for step by step DIY building.


From my reading there seems to be two things going on here with leaks,
one all the stuff you pointed out and two, engine normally creates a
vacuum to draw in fuel (gasoline) in and in the case of a gasifier the
engine draw air into the gasifier to create the fuel. When the engine
needs less fuel it draws less air through the gasifier creating less
fuel, when it need more fuel it draws more air, so any leak will also
be vacuum leaks and impede this process. At least that's how I
interpret it.

Curbie



Posted by Jim Wilkins on October 23, 2009, 11:12 pm
 



I can appreciate the junkyard approach they took, but I think welded
stainless steel would be better for equipment meant to last, since
brazed steel joints are subject to galvanic corrosion. Ever repair a
car exhaust by brazing and see how quickly it rusts out at the joints?

Stainless isn't rustproof. I salvaged some first-generation
Metalbestos double wall chimney with the inner liner heavily corroded
and even perforated in a few places. The outer shell is fairly easy to
cut and form. http://picasaweb.google.com/KB1DAL/Parts#5285937862376318882

jsw

Posted by Curbie on October 24, 2009, 12:02 am
 

On Fri, 23 Oct 2009 16:12:53 -0700 (PDT), Jim Wilkins

Jim,


Your right about stainless steel construction, I've read that the WWII
and FEMA type gasifiers only last for a couple hundred hours of use,
but if I understood Ulysses's point correctly, he was first concerned
about functionality nuances, so in my opinion a cheap and easily
modified approach seems better to master the nuances and finalizing a
design before spending for stainless steel construction and longevity.

I suppose as long as people are aware of the pitfall, they can make a
choice that best suit them?

Good point though.

Curbie


Posted by Ulysses on October 24, 2009, 3:59 pm
 



Yes, but what I was thinking is that, for the most part, the trees have
already been cut down and transported etc. and the leftover debris could be
used in a gasifier.  Stuff that otherwise might go into a landfill.  Mother
Earh News wrote an article about a pickup truck that they were running from
woodgas.  They were fueling it with stuff they picked up on the side of the
road so processing seems to be more for better efficiency and higher power
output rather than an absolute necessity to get the thing to run.  So, if
woodgas-fueled engines became popular sooner or later someone would start
gathering up all the lumberyard leftovers and probably turn them into fuel
pellets and sell them.  Then the government would have to start taxing the
pellets, at least for highway use.  And of course the EPA would have to test
the emissions and slap a catylitic converter and a smog pump on there.


Like I said, I don't know anything about using algae.  It seems like it
would be difficult to cultivate and dry etc but judging from my swimming
pool it's very easy to grow ;-)


When I inquired at a welding newsgroup I was told repeatedly that it would
be very difficult to weld a pipe to a steel drum.  Another option would be
to use something like pipe flanges bolted onto the drum (or whatever
container is to be used) and seal it with something like stove cement.  That
might work.  So far I have read only one account on this NG from someone who
actually built a woodgas generator and it blew up.  I don't remember who it
was or what caused the explosion but that particular person had no more
interest in woodgas generators.  BTW by "generator" I mean a device that
produces the gas, not an electrical generator.

Someone mentioned acids that exist in the vapor/gas and the problems
associated with that.  The "tar" could be filtered out (I was thinking of
using a pre-filter that is cheap and easy to replace) and perhaps then using
an automotive air filter, preferably whichever one is cheapest and easiest
to find--probably a circular one for a carburated engine.  Perhaps the acids
could be removed by using a water-wash filter (forget exactly what they are
called but they were once used in paint booths for lacquer etc).
Unfortunately these require quite a bit of power.  Then the water vapor
might need to be removed or oil added to the mixture to prevent rust in the
cylinder.  Or perhaps an engine that is not made of ferrous materials could
be used.  I read somewhere that the IC engine was originally designed to run
from woodgas/producer gas so these problems must have been worked out
already, at least to some extent.

It sounds to me that getting an IC engine to run from woodgas is not a huge
challenge.  Getting one to run reliably for an extended amount of time seems
to be the tricky part.



Posted by Curbie on October 24, 2009, 5:38 pm
 

Ulysses,

It may help understanding to pull the gasification process apart to
see what's going on inside the gasifier; to my understanding, the
gasifiers have two chambers and for the sake of a simple discussion
we'll call one the heating chamber and the other the reaction chamber.
Also for the sake of discussion we'll assume this hypothetical gasifer
is a FEMA design, running and operating properly.

HEAT CHAMBER:
The bio-mass is gravity feed from the fuel bin (along with a little
shaking produced by bumps in the path) into the heat chamber where
this fuel is sacrificed for 1) heat needed by the reaction chamber
(1000°C or 1850°F), 2) carbon needed by the reaction chamber, and 3)
to vaporize moisture (water) in the fuel for steam also needed by the
reaction chamber.

REACTION CHAMBER:
At this point in a running gasifier the heat chamber is supplying the
reaction chamber with heat, carbon (C) (which is gravity feed and
can't be so small in size as to fall through the reaction chamber
grate), and steam (H2O) and the purpose of the reaction chamber is to
chemical rearrange these molecules into combustible compounds (gases)
that we can fuel an I.C.E. with.

The chemical rearrangement looks like: H20 (steam) along with C
(carbon) rearranges to H2 (2 parts hydrogen) and CO (carbon monoxide),
about 20% of output gas volume for each (the gases we want) along with
60% nitrogen left over from intake air (a gas we don't really want).


Well sort of, my understanding is that preprocessing fuel serves two
functions, one to size the fuel so won't fall through or "bridge" the
reaction chamber grate, and drying the fuel so it contains about 10-15
moisture for steam.


:-) Death and taxes, or tax to death, depending.


The easy to grow part is why I'm thinking about it, I think drying and
sizing is a requirement for all bio gasification.


If it was me, I stick to the FEMA plans step by step and use the few
hundred hour life expectancy to test modifications and than have a
professional weld a stainless steel final design, "test on the cheap,
build to last".


From people who are currently doing this, the big concern is "fly ash"
(what's left over the fuel combustion and is so light it can be drawn
into to output gas stream. Fly ash is BIG-time abrasive and can
destroy an I.C.E. if not removed from the output gas. The gasifier
group uses a cyclone is a type of filtration device that uses
centripetal forces to remove particulate in the output gas stream.
CYCLONE:
http://elevatorman.shawwebspace.ca/pages/view/files_section/


I think your right.
Curbie


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