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

Luke Gardner lgardner at wwest.net
Sun Mar 18 21:20:23 CDT 2012


Greg,
I don't have a lot of time today,  but I have been loosely following along, 
and I Can't help but wonder if things might not be a little easier to 
understand if a Guy stops thinking in temperature and pressure, and started 
thinking about the material of discussion in terms of its kinetic energy.
14.7, or 101.325 aren't magical universal pivot points that natural laws 
swing upon, "normal" Air pressure, isn't hardly ever " normal" at all.  It 
is as much  a figment of our human imagination as monday, or leap day, or 
the millenium.  The only difference between a "suction" and "pressure" 
gasifier is a few PSI and your point of view.
resectfully,
Luke

-----Original Message----- 
From: Greg Manning
Sent: Sunday, March 18, 2012 12:30 PM
To: Discussion of biomass pyrolysis and gasification
Subject: Re: [Gasification] On the subject of H2 and O (was N2 removal)

meant NOT at a great amount (as in very small) sorry all.

G.

On Sun, Mar 18, 2012 at 2:26 PM, Greg Manning <a31ford at gmail.com> wrote:
> 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



-- 
Regards,

Greg Manning,
Brandon, Manitoba, Canada

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