[Gasification] On the subject of H2 and O (was N2 removal)

Greg Manning a31ford at gmail.com
Sun Mar 18 14:26:57 CDT 2012


KELBURN,

THANK YOU !

 This is the EXACT thing I needed to see.... proves my point, EXACTLY.

 I am now of the firm beleif that we CAN (And DO) water gas shift in
suction type gasifiers, where as, blown (pressureized) gasifiers can
NOT do W/G shift.

I think the W/G shift is at a great amount, BUT, it sure proves my
caclulations, almost dead on.

Thank you Thank you Thank you Thank you

Greg



On Sun, Mar 18, 2012 at 12:14 PM, Kelburn Koontz <kelburn_k at yahoo.com> wrote:
> Making Ice with Vacuum
> http://www.youtube.com/watch?v=pOYgdQp4euc
>
> Check out the ideal gas law.
>
> Thanks,
> Kel
>
>
> On Sun, 2012-03-18 at 08:10 -0700, Mark Ludlow wrote:
>> “The steam produced in cavitation is like putting water in a bell jar
>> and pulling a vacuum.  If there is enough vacuum the water will boil,
>> converting it's temperature into energy for the phase change.
>> Eventually you end up with a chunk of ice in the bell jar.”
>>
>>
>>
>> Not so! Not enough latent heat is lost. Sensible heat must be removed
>> also. In outer space, where there are huge radiative heat losses this
>> applies. If folks could make ice with simple vacuum pumps, who would
>> mess with refrigeration? It takes energy to evaporate water, not just
>> vacuum.
>>
>>
>>
>> Plus, when a gas is adsorbed onto a sieve, energy is released. It
>> takes the same energy (and then some) to regenerate the sieves. No
>> free lunch; no where.
>>
>>
>>
>>
>>
>> From: gasification-bounces at lists.bioenergylists.org
>> [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of
>> sabbadess at aol.com
>> Sent: Sunday, March 18, 2012 7:55 AM
>> To: gasification at lists.bioenergylists.org
>> Subject: Re: [Gasification] On the subject of H2 and O (was N2
>> removal)
>>
>>
>>
>> Hi Greg,
>>
>>
>>
>>
>>
>> Sure.  Let's to a simple example so my feeble mind can follow it.
>> When I drop cold chips in my gasifier there is some moisture content
>> in the chips...this is liquid water in the wood cells.  As the chips
>> burn down into the hearth they get hot and the water changes to steam.
>> This phase change absorbs some amount of energy.  Then as the steam
>> goes through the char, some of it does the water gas shift if there is
>> enough heat.  This absorbs even more energy.  The remaining steam ends
>> up as condensate in the cooler.
>>
>>
>>
>>
>>
>> The steam produced in cavitation is like putting water in a bell jar
>> and pulling a vacuum.  If there is enough vacuum the water will boil,
>> converting it's temperature into energy for the phase change.
>> Eventually you end up with a chunk of ice in the bell jar.
>>
>>
>>
>>
>>
>> The water gas shift will not happen in the phase change because there
>> isn't sufficient activation energy availble to make the reaction go.
>> If it did work that way, there would be hydrogen bubbles coming off
>> boat propellers.  That would make a COOL rooster tail!
>>
>>
>>
>>
>>
>> Gasifiers do not run a low enough pressure to vaporize the water, like
>> the bell jar.  I can get the numbers if you want, but you need to be
>> in -13psi range.  That's way more than we pull.
>>
>>
>>
>>
>>
>> Any clearer or still muddy??
>>
>>
>>
>>
>>
>> Stephen
>>
>>
>> -----Original Message-----
>> From: Greg Manning <a31ford at gmail.com>
>> To: Discussion of biomass pyrolysis and gasification
>> <gasification at lists.bioenergylists.org>
>> Sent: Sun, Mar 18, 2012 10:09 am
>> Subject: Re: [Gasification] On the subject of H2 and O (was N2
>> removal)
>>
>> Hi Stephen, thanks for the reply.
>>
>> OK, I somewhat understand you, BUT, wouldn't water be doing a phase
>> change in the core of a gasifier as well ?
>>
>> What I was getting at, is if steam is produced in cavitation in cold
>> water, then wouldn't the shift effect also happen within the core
>> during phase transition (from water as a liquid, to water as a vapor,
>> when heated by the core) within the same boundaries of effect as water
>> to steam in the trailing edge of a propeller ? (all of these
>> situations involve lower that normal pressure zones).
>>
>> Aren't contrails produced in water vapor on the wing tips of an
>> airplane because of this same pressure drop phase shift, causing a
>> dew-point change?
>>
>> The core of most gasifiers runs in a dynamic lower than atmospheric
>> pressure ( a very low internal barometric pressure) (suction based
>> units), so the same shifts should apply  during phase transition,
>> shouldn't they ?
>>
>> I understand that a pressure fed gasifier would behave differently
>> (and I've personally observed this) than a suction based one, I'm
>> speaking about suction based gasifiers.
>>
>> Somewhat lost,
>> Greg
>>
>>
>> On Sun, Mar 18, 2012 at 8:26 AM,  <sabbadess at aol.com> wrote:
>> > Greg,
>> >
>> > The energy doesn't change.  The bond energy in the water is constant
>> > regardless of pressure.
>> >
>> > The cavitation issue is different.  It is a phase change phenomenon, not a
>> > chemical change one.
>> >
>> > Stephen
>> > -----Original Message-----
>> > From: Greg Manning <a31ford at gmail.com>
>> > To: Discussion of biomass pyrolysis and gasification
>> > <gasification at lists.bioenergylists.org>
>> > Sent: Sun, Mar 18, 2012 9:02 am
>> > Subject: [Gasification] On the subject of H2 and O (was N2 removal)
>> >
>> > Greetings List.
>> > Since we are speaking input air, I thought I might ask a somewhat
>> > related question.
>> > Water gas shift. I know there are many that have talked about this,
>> > and I understand the basics.
>> > However, here is the question.
>> > At what negative pressure ( negative in/wc) does the shift move down
>> > the temperature scale, to the point of being within the 1000 - 1200 c
>> > area ?
>> > We all know that propeller cavitation produces steam in water that is
>> > 10 c (or there abouts), I have to assume (not being a chemist) that
>> > the same negative pressure effect would also apply to other principals
>> > when dealing with water.
>> > --
>> >  Regards,
>> > Greg Manning,
>> > Brandon, Manitoba, Canada
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>>
>>
>> --
>>  Regards,
>>
>> Greg Manning,
>> Brandon, Manitoba, Canada
>>
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>
>
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-- 
 Regards,

Greg Manning,
Brandon, Manitoba, Canada




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