[Gasification] W-Gas and P-Gas defined

jim mason jim at allpowerlabs.org
Sun Dec 11 17:39:48 CST 2011 

On Sun, Dec 11, 2011 at 9:57 AM, Thomas Reed <tombreed2010 at gmail.com> wrote:
> Dear Mark
>
> Nice to talk to a chemical engineer.  I have previously always used the term "syngas" to refer to the mixture of CO and H2 resulting from oxygen gasification or steam reforming.  Conventional wisdom said the producer gas made by air reforming would not be good for chemical synthesis.
>
> However, lately I have come across instances of using producer gas for FT synthesis.  I have also been studying the thermodynamics of various reactions.
>
> I believe that CO and H2 should be called "hyperenthalpic", because their heats of combustion (280 kJ/mole) are out of line with all other carbon-hydrogen compounds. One result of this is that it is easy to burn the FT catalyst when using syngas.  However, when using producer gas, the excess N2 buffers the reaction heat, protecting the catalyst.
>


tom, this is true, but you still have to deal with the other (of many)
factors of conversion percentage per pass.  the main reason for pure
syngas in liquification processes is that most are multipass, and if
you have any non-reactants in the stream, then will built up during
the cycling.  if you go in with 50% nitrogen, you are very quickly
going to have nearly 100% nitrogen in your cycle.

the variety of single pass processes we see today make the possibility
of using nitrogen diluted gas much more realistic.  and potentially
even more attractive given the moderation of heating problems you
mentioned above.

after now having tried to make some liquid in our shop from pure
bottled co and h2, i'm pessimistic on the viability of this for small
scale.  even if we get past the challenges of high temps, pressures,
and reasonably selectivity of output to not have a giant kitchen sink
of goop at the end, the new "deal killers" i learned where the
following.  any ideas for solving these?

1.  process requirements to bring the liquid reactor up to operation.
even in simple FT, there are quite rigorous requirements for temp ramp
rate and catalyst activation with one gas or another.  this is a multi
hour process, seemingly on the day long time frame.  it is not as
simple as a "heat it up and go".  you need a fairly ambitious process
engagement that does not work well outside of a fully staffed
industrial environment.

2.  inability to start and stop:
the above prevents easy starting and stopping of the column.  added to
this most catalysts don't seem to like to be cycled back to cold after
activated.  this seems to reduce the effectiveness of most of them,
and only add to their general maintenance problems.

the liquid processes seem to me to require near continuous uptime of
the gasifier.  you want to be able to bring up the column and run it
for days, like you would in a proper FT plant.

as what i've really wanted to do is have another box on the side of
our gasifier/engine "box" that uses part of the gas stream to make
liquids, seeing the above was not welcome news.  if we can't get
liquidifcation processes to reasonable start and stop, with minor
catalyst activation dependencies, it is unlikely to fit well with
personal scale power devices of usual concern here.

that is not to say it can't work tolerably with smaller scale
industrial equipment, say shipping container size, but this would need
to be equipment operating in continuous mode.  this is an outlier of
the main thing most of us work, on, though again not irrelevant.

hopefully i will be proved wrong in this pessimism.  jay hasty of our
group is currently in grad school at stonybrook/brookhaven with
devinder mahajan working on exactly these liquid routes as she things
they can work.  i hope she's correct.  a little liquid on the side of
a "waste biomass to electricity/heat/cooling/shaft power and biochar"
agnostic converter box would be a wonderful thing.

j







> I have not tested these alternate routes and would be interested in your opinion.
>
> <_><><><>
>
> I have had considerable experience with alumina silicate molecular sieves which form a cubic cage about 10 A with 7A holes on the faces of the cubes.    I believe that If a few iron atoms were put in each cube, it would make a powerful FT catalyst and would minimize the wax production.
>
> I have filed a provisional patent application on this and would be interested in your opinion.
>
> Tom Reed
>
>
>
> Dr Thomas B Reed
> The Biomass Energy Foundation
> www.Woodgas.com
>
> On Dec 11, 2011, at 12:46 AM, "Mark Ludlow" <mark at ludlow.com> wrote:
>
>> Amen, James!
>>
>> -----Original Message-----
>> From: gasification-bounces at lists.bioenergylists.org
>> [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of James
>> Joyce
>> Sent: Saturday, December 10, 2011 9:13 PM
>> To: gasification at lists.bioenergylists.org
>> Subject: Re: [Gasification] W-Gas and P-Gas defined
>>
>> Hi Tom, I am supportive of any move away from the use of the term "Syn-gas"
>> for the products of pyrolysis and gasification.
>>
>> As a chemical engineer I wince every time I hear the grab bag of chemicals
>> resulting from pyrolysis and gasification being described with a term that
>> was coined for mixtures primarily consisting of CO and H2, and intended for
>> the purposes of chemical synthesis.
>>
>> All it does is continue the public misconception that syn-gas from any
>> pyrolysis or gasification process can be used to run engines and/or be
>> compressed and stored in fuel tanks for later use. Those on this list will
>> know that this is a long way from reality.
>>
>> It might be consider as pedantic, however in my observation it is often part
>> of a broader deception that can defraud unwitting  investors.
>>
>> Regards,
>>
>> James Joyce
>> Australia
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Sat, 10 Dec 2011 08:34:17 -0500
>> From: Thomas Reed <tombreed2010 at gmail.com>
>> To: Discussion of biomasspyrolysis and gasification
>>    <gasification at lists.bioenergylists.org>,    Hugh McLaughlin
>>    <hmcLaughlin at alternabiocarbon.com>,    Paul Anderson
>>    <psanders at ilstu.edu>, William Ayres <waayres at gmail.com>,
>> Kathy Nafie
>>    <kathynafie at yahoo.com>, Jim Fournier <jim.fournier at gmail.com>,
>>    Mukunda HS <hsm.cgpl at gmail.com>
>> Subject: [Gasification] W-Gas and P-Gas defined
>> Message-ID: <2EBBF444-DF99-4298-854F-B3DF0173CF04 at gmail.com>
>> Content-Type: text/plain;    charset=us-ascii
>>
>> 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
>>
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>
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