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

Sun Mar 18 21:59:15 CDT 2012

Greg blown gasifiers typically operate at a few inches of positive pressure (0.01 ATM) and suction gasifiers at a few inches negative, so both are essentially at atmospheric pressure unless the pressure is purposely increased or decreased .

Tom Reed

Thomas B Reed 

On Mar 18, 2012, at 3:26 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
> 
> _______________________________________________
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