[Gasification] Two stage gasification

Sun Oct 28 15:44:46 EDT 2007

Jim and others.

The Danes have been doing high quality two stage gasification for years.

Just GOOGLE  two stage gasification Technical University of Denmark and you 
will get more information on high quality gas producing , simple to operate 
gasifiers than you will ever want.

Let us not re-invent the wheel here or make high quality gas seem like an 
impossibility.

Art Krenzel

----- Original Message ----- 
From: "jim mason" <jimmason at whatiamupto.com>
To: "Mark Ludlow" <mark at ludlow.com>
Cc: <gasification at listserv.repp.org>
Sent: Sunday, October 28, 2007 12:31 PM
Subject: Re: [Gasification] combustion of tarry producer gas

> On 10/27/07, Mark Ludlow <mark at ludlow.com> wrote:
>>
>>  I agree, in priciple. But the challenge for widespread application of
>> gasification demands that small-unit applications not be fuel sensitive.
>> (Who wouldn't love to have almond shells to run?) Face it: an updraft
>> gasifier where fuel can be dumped on a reactive bed is the simplest
>> scenario. Sure, it takes no advantage of passing the pyrolyzed gas 
>> through a
>> cracking zone. But I have a sneaking suspicion that combining all
>> requirements of tar-free gasification in a single device may not be the 
>> most
>> practical solution in all instances (my apologies to Doug Williams). It's
>> certainly more elegant to have a single chamber doing gasification and
>> cracking but who would refuse access to a fuel source composed of only
>> charcoal even if, lb-for-lb, its HHV was less than properly-sized dry
>> biomass? Everyone would rather avoid tar from the outset by having pure C 
>> as
>> a fuel (in an ideal world). But is it possible to "close-couple"
>> gasification and tar cracking without making them integral to a single
>> process?
>>
>
> i apologize if i created the impression that i think updrafts are off the
> table.  of course there are many applications and subprocess needs where 
> an
> updraft is well suited.  the requirements for dealing with the output gas
> can be complicated if more than an immediate close coupled burn, without
> passing through a fan.
>
> mark is correct that a great attraction of an updraft is its fuel
> flexibility.  as the air/gasflow is going in the opposite direction of
> gravity, they are much less likely to cake up.  higher moistures will only
> degrade the energy in the product gas, but not stop the gasifier from
> working, like in a downdraft.
>
> at this point i don't find any single vessel solution to be able to
> adequately process fuels with the needed flexibility for tolerable real
> operation, and produce a consistent tar free gas.  the self regulating
> simplicity of combustion against reduction, with radiated/conection heat
> running pyrolysis, in a single vessel is elegant in its minimalism, but it
> is famoustly difficult to control.  the self-regulating character of these
> single vessel solutions only work within a very narrow band of fuel and 
> air
> humidity conditions.  i find the world to not easily provide these
> conditions.  thus most gasification efforts become fuel standardization
> efforts.  and very few survive this transformation.
>
> most all my work towards fuel agnostic, tar free gasifiers, is moving
> towards pulling each of the zones apart and contending with them 
> separately,
> either in dedicated and well separated spaces in a "single vessel", or a
> fully separate dedicated vessel.  the processes can then be recombined and
> controlled actively with microprocessors so that the great variation in
> performance as fuel changes, can be compensated for in real time.  i don't
> have a finished system yet, but i'm going as fast as i can.
>
> such gasifiers cannot be built from junk quite so easily, but they also 
> hold
> the potential to actually work in real world conditions.
>
> for inspiration, i keep a large dumpster bin of real world organic matter
> outside my shop.  it has the waste of the world in it that i think a
> gasifier should be able to deal with: mixed construction waste with nails,
> plastic cups, newspaper, cardboard boxes, dimensioned lumber, coffee, 
> brush
> clippings, tires, water bottles, etc etc etc.  i stare at this pile daily 
> to
> remind myself of the range of what a gasifier needs to be able to intake 
> to
> actually fulfill its promise of "energy from any waste biomass"
>
> right now we are mostly at "energy from very carefully preprocessed forms 
> of
> organic waste, handled with such care and knowledge, that they are really 
> a
> high grade fuel again before they go in the gasifier".  and thus is why so
> few current small scale gasfiier installations ever work in the end.  the
> limitations of fuel type and condition, as well as expertise required to
> maintain these conditions, is not reasonable for typical users.
>
> we are not going to solve this problem with any minor tweak to an imbert
> type.  but i think we can solve it by the thoughtful separation and 
> control
> of the subprocesses, with active embedded control for recombining the 
> parts
> and flows between them.  this will result in hybrid systems that have
> combinations of various "traditional" types into a single system.  and 
> yes,
> updrafts might be quite important as subprocesses in such a system.
>
> j
>
>
>
>
>
>
>
>
>
>
>
>
>
> Rex Z. has expressed a vision of a dual-zone reactor. Few experimenters or
>> small-scale devotees are likely to attempt the fluid bed model that he
>> describes, but a critical notion is the physical division of gasification
>> and 'refinement' within a continuous flow stream. In its simplest
>> expression, optimizing a primary generator to become an efficient 
>> converter
>> of solid feed substrate to gas is one task; and providing the environment 
>> to
>> reduce this gas to short-chain combustible components becomes the second
>> task.
>>
>>
>>
>> Gasification, in its present popular incarnation, assumes that cracking 
>> of
>> tarry gas requires a parasitic process deriving energy from the primary
>> reaction zone. This is very elegant, in theory, but is dependent on a 
>> number
>> of mechanical parameters such as fuel condition and form factor. I ask:
>> cannot the tars from a simple updraft gasifier be considered a fuel 
>> source
>> unto themselves?  Between their gaseous state and their troublesome
>> crystallized state there must be a liquid state that would facilitate 
>> their
>> transport back into either the primary gasification/reduction zone or a
>> secondary oxidation zone, providing energy for the primary gasification
>> transformation.
>>
>>
>>
>> Am I dreaming?
>>
>>
>>
>> Mark
>>
>>
>>
>> *From:* jimmmason at gmail.com [mailto:jimmmason at gmail.com] *On Behalf Of 
>> *jim
>> mason
>> *Sent:* Saturday, October 27, 2007 12:27 AM
>> *To:* mark at ludlow.com; Discussion of biomass pyrolysis and gasification
>> *Subject:* Re: [Gasification] combustion of tarry producer gas
>>
>>
>>
>>
>>
>> On 10/26/07, *Mark Ludlow* <mark at ludlow.com> wrote:Tom,
>> What do you estimate that the temperature of condensation of typical
>> woodgas
>> tar is?
>> Mark
>> --------------------------
>>
>> this is commonly desciribed as above 350degC
>>
>> but really, there is a tremendous variation between primary, secondary 
>> and
>> tertiary tars.  or light and heavy.  depending how terms are defined.
>>
>> leland has much more experience in long running installation than i and
>> many others here.  my knowledge is only from running prototype rigs to
>> date.  so in general, i defer to leland and other like experienced elders 
>> in
>> this endeavor.
>>
>> so yes, avoid updraft gasifiers with biomass at nearly all costs.  make
>> clean gas from the begininng.  innumerable problems will be less onerous
>> downstream if you  do so.
>>
>> jim
>>
>>
>>  On 10/26/07, *Mark Ludlow* <mark at ludlow.com> wrote:
>>
>> Tom,
>> What do you estimate that the temperature of condensation of typical
>> woodgas
>> tar is?
>> Mark
>>
>> -----Original Message-----
>> From: gasification-bounces at listserv.repp.org
>> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of
>> LINVENT at aol.com
>> Sent: Friday, October 26, 2007 10:35 PM
>> To: jimmason at whatiamupto.com; gasification at listserv.repp.org
>> Subject: Re: [Gasification] combustion of tarry producer gas
>>
>> Burning tarry producer gas may appear to be an easy job, but after a 
>> while
>> there are problems with it. One is that the tars may crack around the hot
>> combustion areas and carbon up the pipes, ports apertures or other parts
>> exposed to
>> the direct or indirect heat from the combustion of the gas. Tars will
>> condense
>> anywhere in the transport pipes. Once condensed, they will solidify over
>> time
>> and block the pipes. They also drip off the end of the combustion pipe
>> into
>> the combustion chamber and pile up or burn within the chamber. If any 
>> long
>> term
>> usage of them is expected without significant pipe cleaning downtime, the
>> gas
>> needs to be clean.
>>
>>
>>
>> Sincerely,
>> Leland T. Taylor
>> Leland T."Tom" Taylor
>> President
>> Thermogenics Inc.
>> 7100-F 2nd St. NW Albuquerque, NM 87107
>> Phone:505-463-8422 Fax:505-268-9206 (call first)
>> Web: thermogenics.com
>>
>>
>>
>> **************************************
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>>
>>
>> --
>>
>> --------------------------------------------------------------------------------
>> jim mason
>> website: www.whatiamupto.com
>> current project: mechabolic ( http://www.mechabolic.org)
>> announce list: http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com
>>
>
>
>
> -- 
> --------------------------------------------------------------------------------
> jim mason
> website: www.whatiamupto.com
> current project: mechabolic (http://www.mechabolic.org)
> announce list: http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com
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> 