[Stoves] Burning low quality ethanol

[Paul S. Anderson]

Dear Crispin, Anil, William, Philip and all,    (If you are interested in
alcohol stoves or alcohol fuel, this message should be important.  If not
interested, don't bother.)

Anil, can you direct us to your 1984 publication on the Internet, please.

Rajvanshi, A.K., 1984. Distillation of Ethyl Alcohol from Fermented Sweet
Sorghum Solution by Solar Energy, Final report submitted to Department of
Non-Conventional Energy Sources, New Delhi.

You say that the people can make low-quality (high water content) ethanol.  I
want to know those methods.  They should be distinctly different from the
"first-pass" of ethanol production in modern distilleries that yields only 5%
of water in the alcohol.  Nobody else has said anything about the 
production of
low-quality ethanol.  Please provide the info or links.

Your paper about your alcohol stove says that you were intentionally diluting
the regular alcohol with water.  The purpose was to make the stove safer,
correct?  Is there any other reason to dilute otherwise good ethanol?

But the water content must be raised from ambient temperature to 100 
deg C, and
then even more heat (latent heat) is needed to make the liquid water 
into steam
(still at 100 C).  That seems like a major amount of heat energy expended just
because of the water content.  Safety is important, but at what 
trade-off? Discussion is needed.

To Philip Lloyd:  Please write.  Your comments would be appreciated.

To William Carr who wrote:

> .... in the more general area of alcohols,  Butanol is the solution 
> to the problem.    It doesn't have to be  double-refined to burn 
> well, as ethanol does.

I am referring to the SINGLE-refined ethanol, which is fine for thermal
applications.  The double-refined is necessary for placing ethanol into
gasoline, (and probably for some other uses where no water is tolerated.)

I did find your butanol comments to be quite interesting.  What is the 
"problem"
that prevents butanol from getting the funding and political support that is
given to ethanol?

And to Crispin Pemberton-Pigott:   (much snipped)

You mention the wikipedia article.  It is a modern classic that is frequently
cited, along with the material at     zenstoves.com
http://en.wikipedia.org/wiki/Beverage_can_stove

Wikipedia "lists a couple of patents issued for them at the bottom."  I 
have not
yet looked at them.  Anyone able to make quick comments?

> I am preparing another go at the
> calculation of heat available from burning ethanol.

I look forward to that calculation.
>
> In industry the target for 1 pass through a distillation is 5% water or
> less. Given the close condensation temperatures, that is pretty good and
> that is what is sold normally.

Unfortunately, in the USA I seem to only get the 100% stuff at about US$12 per
gallon (nearly $4 per liter).  Yet in Ethiopia, the market price of ethanol
(what Project Gaia pays) is only US 25 cents (one sixteenth what I 
pay). (Joke:  Where is George W. Bush when I need him??)

> If you have more water than that, someone
> started out at 5% and diluted it to sell water at $1000 a cubic metre.

An excellent point.  And think of the added transportation costs.  Ethanol
should not be watered intentionally (unless for safety that Anil cites??).

But if Anil or others can show how to economically produce ethanol with 
a range
of 50% to 6% water content, then there is a different story.  The issues then
include the wasted heat energy to boil off the water, unless there is 
selective
vaporizing that liberates the alcohol and leaves the water behind (as is the
case with the self-pressurized alcohol stoves like the beverage can stoves and
the Lily stove).

> The ethanol gasifiers (which you seem to have) overcome this although you
> still pay a lot for the water.

Please allow me to shout once:  Alcohol stoves VAPORIZE a liquid, and DO NOT
GASIFY.  Gasifiers are generally accepted to refer to making gases from solid
dry biomass.

> What is the latent heat of evaporation of ethanol? And its specific heat?

Good questions, and I do not have the answers.  Help please, anyone.

> One problem I see is that in some countries you are not allowed to heat the
> fuel in the tank above the evaporation point at any time because it is a
> safety hazard. You can pressurize it, but not heat it because you can easily
> depressurize it but not cool it quickly should it fall over.

I certainly hope I do not need to get involved with changing of laws. 
Seriously, I have found no problems with heating these self-pressurizing
alcohol burners.  Reasons are:

1.  Construction with numerous holes in the top.  The pressure is quite low.

2.  I restrict my units to quite small sizes.  7 cm diameter (3 inch) tincans
are excellent.  I have gone up to 15 cm (6 inch) diameter.  These stoves work
on the principle of heat from the fire being able to heat the metal cans that
in turn heat the alcohol that becomes vaporized.  This heating is selective,
meaning it occurs at the metal surfaces.  Vaporization of some molecules will
cause cooling of the surrounding liquid, keeping the majority of the liquid
below the vaporization point until that liquid reaches the warm metal.  When
the liquid is held in a fiberglass or ceramic fiber material inside the
burner-can, the liquid does not readily flow, especially not in the upper part
of the container because gravity keeps the fluid tending to sink lower 
into the
can.  The use of fiberous fillings is found in the CleanCook stove (and other
Dometic AB stoves) and in the Lily burner.  I did not see any reference to
fiberous fillings in the beverage can stoves, but it could be used there.

And when the fire is extinguished, the vaporization (if fluid is still 
present)
quickly drops (perhaps 5 to 10 seconds later), and not even a match at the
vapor outlets will re-ignite the can.  In some ways the steel of the Lily
burner might be superior for safety over similar stoves made of aluminum or
brass, but that topic also needs further thought and experimentation.

I have tipped the Lily burner intentionally, and done a few other 
things without
being very careful, and I have never had a safety-threatening situation at my
workbench.  But of course, EVERY stove with any fuel could cause a fire under
some irregular circumstances.  This will be a topic for continual vigilance.

> Come to think of it, that would prevent the Lily stove reaching some
> markets.

If so, then I will need to focus on the places that will allow such 
stoves. Please send me a list of the places that you know of that have 
restrictions
against small containers of alcohol being made warm, but not warming 
the entire
liquid contents to the temperature of vaporizing.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson




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