[AT] gasifiers

[charliehill]

Ken,  in the youtube videos I've watched most of the issues you have 
mentioned have been addressed.  I won't try to recite the answers as I'm 
sure I would get most of them confused or incorrectly recalled.  I would 
suggest, if you have a high speed connection, you spend some time watching 
the videos.  Many of them are trash but some are very good.   The filtering 
that I have seen in most systems is done by merely passing the gasses 
through wood chips or other bio mass that will eventually be used as more 
fuel for the gasifier.  This in turn makes those chips a bit dryer and also 
covered with the tars it makes them better fuel.  Apparently, if the hot 
zone (I forget the term) of the gasifier is correctly constructed and 
combustion air properly channeled into the bio mass, most of the tars and 
volitile compounds are broken down in the gasifier and MOST of what comes 
out the pipe is H2 and CO with some methane.

In the one video of the guys building the FEMA designed rig out of old 
drums, the guy says what he is getting out the end and burning is nearly 
pure hydrogen.  He makes that assumption by the color of the flame and the 
odor (or lack there of) of the fumes from the flame.

In one of the other videos a guy points out that he is burning CO as 
evidenced by a beautiful blue flame.

Charlie
----- Original Message ----- 
From: "Ken Knierim" <ken.knierim at gmail.com>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Thursday, October 15, 2009 11:10 AM
Subject: Re: [AT] gasifiers


> On Thu, Oct 15, 2009 at 6:57 AM, Gene Dotson <gdotsly at watchtv.net> wrote:
>
>>    Wood and all biomass fuels burn in 2 stages. The first and most
>> noticable is the gas burning that is driven out by the heat, this is the
>> flame you like to see in the fireplace. The second stage is the ember or
>> charcoal stage when the solid part of the wood is consumed.  A fuel 
>> heated
>> or burned in a limited oxygen atmosphere will drive the gas from the fuel
>> and when directed to a chamber with free oxygen will then be consumed 
>> with
>> very little waste or smoke.
>>
>>    All biomass fuels contain gas as a normal product of growth, mostly
>> methane. Gas can be rendered by using heat or pressure or a combination 
>> of
>> both as nature does in the production and accomulation of natural gas.
>>
>>    Many have noticed that burning wood that has laid for many years in 
>> the
>> woods will burn with less visible flame than fresh wood due to the loss 
>> to
>> the atmosphere of the gases. The solid mass is still there and burns well
>> in
>> the ember stage. (I use ember stage as I don't know the actual term).
>>
>>    I have wondered how much gas could be extracted from sawdust and a
>> system to pressurize it and capture the gas?
>>
>>                        Gene
>>
>>
>>
> Gene,
>    I had a similar thought, but possibly using chipped wood instead of
> sawdust (basically the same, just different particle size). Steve's
> information that the gases are corrosive surprised me but after dealing
> semiconductor processes for awhile, there are methods of handling 
> corrosive
> and toxic materials. It's good to know BEFORE you start building the 
> system,
> certainly. Thanks Steve.
>    My armchair guess is that with good filtering the gases can be
> compressed for storage. It would depend on the gas makeup but I suspect 
> that
> with enough pressure, fractions could be drawn off so that various 
> different
> portions of the gases could be separated and handled appropriately. I'm 
> not
> sure compression is the best idea for all though; possibly a centrifugal
> separator would be easier for some gases (like H2). Compressing and 
> storing
> hydrogen has some issues but there are folks working those issues.
> Personally I see hydrogen as an energy storage medium rather than a fuel 
> per
> se. I can't help but wonder if some of the CO and possibly other gases
> couldn't be burned off or reused in the system cycle with the addition of
> some water to optimize hydrogen production. I'm not a chemist so I don't
> know the answers and it's possible things would bond back together inside
> the system before it could be cooled and separated, for all I know. CO is 
> a
> potential fuel, along with having some negative affects on humans and
> atmosphere but if it were up to me I'd use it in the reactor to get more
> hydrogen fuel (if it made sense and could be made to work without gumming 
> up
> the system).
>    Logically, having a gasifier is part of the picture. Doing something
> with it is the next obvious step. Right now the simplest and easiest way 
> to
> handle the gas is for a heating application. That would give a baseline 
> for
> the amount of energy being released. How to separate the gas and compress 
> it
> becomes the next step but I see it as a more capital intensive phase.
> Compressors aren't cheap unless you have one laying around and safe 
> handling
> of stored energy starts to get the interest of the fire marshals. What are
> the gases, other than CO and H2? And how much do the concentrations vary,
> depending upon the sawdust you're feeding it, the temperature and moisture
> of the fuel bed, etc?
>
> Very interesting topic.
>
> Ken in AZ
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