[Gasification] P-Gas Speculation

[Thomas Reed]

Tom Miles

To the best of my knowledge no one has analysed P-gas.  If anyone has the ability to do this, I'm sure we would all be in their debt.  If not, maybe "I'll  do it myself" (said the little red hen).  

In the absence of hard data, we are free to speculate.  Taking CH2O as a sufficient proxy for cellulose, wouldn't it be nice if 

     CH2O + heat ==> CO + H2

Unfortunately, using my magic numbers, this is endothermic to the tune of 

(280 + 280) - (420+ 240- 180 = 480) = 80 kJ/ mole, because CO and H2 are so hyperenthalpic.  

So a more likely equation could be

     CH2O + 0.4(O2 + 3.76 N2) ==> 0.4 CO2 + 0.6 CO + H2  

448-480 = -32 kJ/ mole,  more than sufficiently exothermic to yield a reaction temperature of 500-800 C,  and an A/F ratio of 1.9.  I have measured the A/F ratio in a glass gasifier down too almost 1.0,  where the gas would be much richer.  

I'm planning a blog to contain some of these notes.

Patience.

Tom Reed, (I could add "Dr. P-gas, but I'm too modest)



Dr Thomas B Reed 
The Biomass Energy Foundation
www.Woodgas.com

On Dec 10, 2011, at 9:26 AM, "Tom Miles" <tmiles at trmiles.com> wrote:

> Tom Reed,
> 
> For a start, has a laboratory characterized the gas and charcoal from
> pyrolytic gasification and compared it to "wood gas" or char from pyrolysis
> or gasification? I have not seen data plots from a gas analyzer on a TLUD or
> full characterization of the gases, tars or chars. 
> 
> Thanks
> 
> Tom Miles
> 
> -----Original Message-----
> From: gasification-bounces at lists.bioenergylists.org
> [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Thomas
> Reed
> Sent: Saturday, December 10, 2011 5:34 AM
> To: Discussion of biomasspyrolysis and gasification; Hugh McLaughlin; Paul
> Anderson; William Ayres; Kathy Nafie; Jim Fournier; Mukunda HS
> Subject: [Gasification] W-Gas and P-Gas defined
> 
> Dear Gasification list
> 
> Well defined terminology is fundamental to a discussion of the science and
> praxis of any subject.   I am proposing two new words for the different
> gases we make.  They will help clarify  discussions we have and will have
> here at the "Discussion of biomass pyrolysis and gasification " list.  
> 
> These are proposals, and I hope they will spark a discussion of this and
> other terms that have grown up helter skelter.  We welcome alternate
> suggestions.  
> 
> <><><>
> 
> WOODGAS is a term I have been using for thirty years.  In German it is
> Holzgaz, an exact translation, holz being the German name for wood.  It
> refers to the gas made in gasifiers that completely convert wood to
> combustible gas, often for use in IC engines.  It is the name of our website
> where we sell books on gasification and Woodgas cookstoves.
> 
> For this discussion and others, I propose the abbreviation "W-Gas".
> 
> Wood is composed of ~20% lignin and ~80% cellulose (cellulose plus
> hemicellulose). On heating in the absence of air, the cellulose produces
> mostly the Woodgas, while the lignin is converted to charcoal.  Since the
> lignin is the principal source of tars in Woodgas (up to 2% by weight of the
> wood) tar removal is a very big problem for using W-gas in engInes.  
> 
> <><><><>
> 
> More recently (starting in 1985)  we have developed a new form of "PYROLYTIC
> gasification" in which air is admitted to a dense bed of wood pellets, chips
> or sticks, forming an auto pyrolysis zone passing up or down through the bed
> and burning a small fraction of the pyrolysis gas to convert the remaining
> cellulose to a combustible gas which can be used for cookstoves and charcoal
> generation. Paul Anderson has dubbed the stoves "TLUD, Toplit Updraft"
> stoves.  
> 
> The TLUD gas composition has not been well characterized yet, but I'm hoping
> someone will do so soon (possibly me). ( In an attempt to measure tar, I
> condensed about 1/2 % of a non sticky grey soot in a four foot X 4"
> galvanized stove pipe.). 
> 
> I propose the name "P-Gas" for the gas made from mostly the cellulose in
> this process.
> 
> (Incidentally, the charcoal made in this 600-800C process is significantly
> different from conventional charcoal, and has much less tar and much higher
> absorption properties.  It could be called PG- (PYROLYTIC gasification)
> charcoal. )
> 
> <><><>
> 
> I hope that this will spark a discussion of this and other terminology used
> in this list.  Since Tom Miles is the moderator of this list, I'd like to
> appoint him as the final arbiter of terminology for the list.
> 
> 
> 
> 
> Dr Thomas B Reed 
> The Biomass Energy Foundation
> www.Woodgas.com
> _______________________________________________
> Gasification mailing list
> 
> to Send a Message to the list, use the email address
> Gasification at bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenerg
> ylists.org
> 
> for more Gasifiers,  News and Information see our web site:
> http://gasifiers.bioenergylists.org/
> 
> 
> 
> _______________________________________________
> Gasification mailing list
> 
> to Send a Message to the list, use the email address
> Gasification at bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org
> 
> for more Gasifiers,  News and Information see our web site:
> http://gasifiers.bioenergylists.org/