[Gasification] OT Gasification and ethanol production from biomass

[Mark Ludlow]

Harmon,

The link you supplied refers to an alternative I mentioned: molecular
sieves. This is the method that is commonly used by industry. The typical
sieve is a 3-A (3 angstrom porthole with a cation charge). It works great
for binding water. But it requires regeneration for re-use and regeneration
is not as simple as the simple dehydration possible with calcium chloride,
silica gels or some other material that binds water through hydration. You
need to add lots of heat (BTW, it is quite exothermic in its uptake of
water, like calcium oxide) or use less heat but envelope it in an atmosphere
with a very low water partial pressure (vacuum drying works great).

I buy it for $1/lb in 55-gal drums. In its virgin state it absorbs 22% of
its mass in water. That's $5/lb for water absorbed and, needless to say, you
better keep your drum very tightly sealed.

There's probably a tie-in with gasification: the regeneration could make use
of a high-quality waste heat stream, (or you could just create a wood-fired
regeneration system. In any case, azeotroping the water with toluene proved
more practical for me. n-propyl alcohol is another effective agent and isn't
costly. It forms a water-rich azeotrope so it can be reused many times. I
bought a condenser off of e-Bay and I was given an old glass-lined reactor
which I used as a reboiler (heated with low-grade steam).

It seems to me that if you can get by with 90% or so ethanol it's a big
plus. I side with Peter here. My experience was motivated by the need to
remove water that was created in a reaction in which EtOH was the solvent.
Final water content would be in the 25PPM range because the silane
(silicone-based) group I was reacting with is extremely sensitive to water,
(similar to isocyanurates in urethanes).

The real question for the home-brewer is how much water can you tolerate? I
never considered the down-home (KISS) solutions that others have offered
because my definition of absolute alcohol was pretty extreme. Upon
reflection, I like the use of starches like toasted rice which when soaked
in ethanol sounds like a pretty good breakfast after a night of ethyl
alcohol overindulgence.

Best regards,
Mark

-----Original Message-----
From: gasification-bounces at listserv.repp.org
[mailto:gasification-bounces at listserv.repp.org] On Behalf Of Harmon Seaver
Sent: Friday, June 01, 2007 9:17 PM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] Gasification and ethanol production from biomass

Peter Singfield wrote:
> At 09:03 AM 6/1/2007 -0500, you wrote:
>> Mark Ludlow wrote:
>>   And, BTW, getting 100% is not really all that difficult for
>> individuals -- ask the guys who make anhydrous ethanol to use to make
>> biodiesel. It's definitely doable in the backyard, and not too expensive
>> to set up.
>> -- 
>> Harmon Seaver
> 
> 
> Anhydrous ethanol is the preferred "product" if it can be indeed achieved
> on micro scale.
> 
> Sounds like it is being accomplished -- can you supply more leads??
> 

http://journeytoforever.org/ethanol_link.html#anhydrous

-- 
Harmon Seaver

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