May 1999 Gasification Archive

From Reedtb2 at cs.com Sat May 1 08:44:15 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Gasifier Ignition Systems.
Message-ID: <60d13b3e.245c5129@cs.com>

Dear Ben Russell et al:

Ben asks..

I am wondering what recommendations or experience you may have to share
regarding automatic or semi-automatic ignition systems for small downdraft
gasifiers.

Does anyone know of a source for reliable off-the-shelf commercial units
which are small enough for easy access, adjustable enough to provide a good
long flame and also cost-effective overall ?

I look forward to your comments.

Ordinarily I would reply only to Ben, but I presume the answer could be
useful to others and I have a more general comment.

We are fortunate indeed to live in an age where easy safe solutions are
available for so many problems. In particular, I go to my GRAINGER catalogue
and find various autoignition devices available. (There are a number of
other technical suppliers out there, and I hope that someone will add other
useful names of where to buy...) They typically use a high voltage or
piezoelectric spark for ignition and sense that ignition has occured by a
thermocouple or pressure bellows. If ignition does not occur gas won't turn
on.

Most of us have such systems in our home furnaces and water heaters and they
have probably saved a few million lives.

It sounds like Ben is looking for a reliable gas ignitor, not a gasifier
starter. We here at Community Power Corporation are planning to build
"Turnkey" power systems, and a part of turnkey would be igniting the
gasifier. Electric ignition of barbecues is common in the U.S. (Calrod type
heater plugged into 120 V power), and in principle one could put such a
device in a gasifier for startup of gasifier (as opposed to starting gas
flame).

I would appreciate any other suggestions about how to start gasifiers. In
1980 I was starting a new gasifier with an oxy-acetylene torch through the
touch hole. There was a loud bang, hot gases shot out and burned off my
eyebrows. (They grew back). I don't recommend this method.

I have in my museum "gasifier starter matches" from Sweden in WWII. They are
about 15 cm long, 1 cm wide and coated with magnesium powder. SPECTACULAR.

Cheers and be careful,. TOM REED

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From fractional at willmar.com Sat May 1 17:50:28 1999
From: fractional at willmar.com (fractional@willmar.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Gasifier Ignition Systems.
In-Reply-To: <60d13b3e.245c5129@cs.com>
Message-ID: <372036BB.A121FAB3@willmar.com>

Hello Tom and Ben,

In regards to gasifier igniters, my old gasifier is set up for the standard
pyrocouple controlled propane burner but the firestick idea is most interesting.
I use these compressed sawdust and wax sticks for wood fire and charcoal
ignition. They work great, kindling is almost not required.
How would a 3/4" round stick of nitrated sawdust bound with dextrin do for
starting?
I think the nitrating is necessary in the confinement to insure fire retention.
It would certainly burn much longer than a popsicle stick with magnesium but
cooler. An unnitrated firestarter burns for 12 minutes and they are only 1/4"
thick. They could be easily and cheaply made by rolling them up and letting
them dry in the sun.
It's certainly low tech and reliable, even a 40 below.

Alan

Reedtb2@cs.com wrote:

> Dear Ben Russell et al:
>
> Ben asks..
>
> I am wondering what recommendations or experience you may have to share
> regarding automatic or semi-automatic ignition systems for small downdraft
> gasifiers.
>
> Does anyone know of a source for reliable off-the-shelf commercial units
> which are small enough for easy access, adjustable enough to provide a good
> long flame and also cost-effective overall ?
>
> I look forward to your comments.
>
> Ordinarily I would reply only to Ben, but I presume the answer could be
> useful to others and I have a more general comment.
>
> We are fortunate indeed to live in an age where easy safe solutions are
> available for so many problems. In particular, I go to my GRAINGER catalogue
> and find various autoignition devices available. (There are a number of
> other technical suppliers out there, and I hope that someone will add other
> useful names of where to buy...) They typically use a high voltage or
> piezoelectric spark for ignition and sense that ignition has occured by a
> thermocouple or pressure bellows. If ignition does not occur gas won't turn
> on.
>
> Most of us have such systems in our home furnaces and water heaters and they
> have probably saved a few million lives.
>
> It sounds like Ben is looking for a reliable gas ignitor, not a gasifier
> starter. We here at Community Power Corporation are planning to build
> "Turnkey" power systems, and a part of turnkey would be igniting the
> gasifier. Electric ignition of barbecues is common in the U.S. (Calrod type
> heater plugged into 120 V power), and in principle one could put such a
> device in a gasifier for startup of gasifier (as opposed to starting gas
> flame).
>
> I would appreciate any other suggestions about how to start gasifiers. In
> 1980 I was starting a new gasifier with an oxy-acetylene torch through the
> touch hole. There was a loud bang, hot gases shot out and burned off my
> eyebrows. (They grew back). I don't recommend this method.
>
> I have in my museum "gasifier starter matches" from Sweden in WWII. They are
> about 15 cm long, 1 cm wide and coated with magnesium powder. SPECTACULAR.
>
> Cheers and be careful,. TOM REED
>
>
> Gasification List SPONSORS and ARCHIVES
> http://www.crest.org/renewables/gasification-list-archive

Gasification List SPONSORS and ARCHIVES
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From 146942 at classic.msn.com Sun May 2 12:39:44 1999
From: 146942 at classic.msn.com (skip goebel)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: storage
Message-ID: <UPMAIL01.199905021413300504@classic.msn.com>

Another way to store gas, and scrub the co2 at the same time is to let water
absorb it. I know, at first this sounds crazy, but I remember working at a
winery and putting so2, co2 and other gasses into the tank that had about 10
lbs of head pressure. The gas stays in naturally.

It may take a lot of water, but water is cheap, easy to work with and store.
Why don't you folks quit chasing that bag rabbit and experiment on just how
much gas can be stored in water?

As an aside, couldn't certain minerals be added to the water that could react
or absorb certain gasses more readily? The idea being to grab more hydrogen
or esters and ignore the co2.

Humbly you'ins,
Skip Goebel
Sensible Steam

www.sensiblesteam.com

Gasification List SPONSORS and ARCHIVES
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From 146942 at classic.msn.com Sun May 2 15:00:48 1999
From: 146942 at classic.msn.com (skip goebel)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: More gas storage.../charcol
Message-ID: <UPMAIL01.199905021820440395@classic.msn.com>

has anyone tried taking charcol or coke, putting in a strong container and
holding under a vacuum, then going ahead and admitting the gas to that and
letting it absorb into the charcol or coke, then burning it?
one could sprinkle some lime in there to grab the co2......

skip
sensiblesteam.com

Gasification List SPONSORS and ARCHIVES
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From thermogenics at worldnet.att.net Mon May 3 11:36:13 1999
From: thermogenics at worldnet.att.net (Steve Brand)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Ash Stabilization
Message-ID: <199905031536.LAA22177@solstice.crest.org>

Gasification List:

Do any of you have current information on handling of ash with = heavy
metals ? There was some work done by NREL and EPA/RREL a while back on
= this... Looking for equipment to form construction blocks, use as
aggregate, = etc. Thanks

Stephen C. Brand
Vice President, General Manager
Thermogenics, Inc
Tel; (505) 344.4846
Fax: (505) 344.6090.

From thermogenics at worldnet.att.net Mon May 3 21:49:53 1999
From: thermogenics at worldnet.att.net (Steve Brand)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Ash Stabilization
Message-ID: <199905040149.VAA25559@solstice.crest.org>

Gasification List:

Stephen C. Brand
Vice President, General Manager
Thermogenics, Inc
Tel; (505) 344.4846
Fax: (505) 344.6090.

From rnelson at oz.oznet.ksu.edu Thu May 6 07:33:32 1999
From: rnelson at oz.oznet.ksu.edu (RICHARD NELSON)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <123A8984CA5@oz.oznet.ksu.edu>

In Manhattan, Kansas we have a potential biomass project using
tree trimmings to supply heat either for hot water or to be used in
conjunction with natural gas at a cement facility. In the latter
case we are possibly going to need to gasify the biomass which leads
to my simple questions but ones I had better get expert advice on
before I proceed any further.

For every one pound or ton of tree trimmings that we gasify in a
commercial scale gasifier, how many cubic feet of gas can we expect
to generate and use and what is the Btu content of that gas? Also,
for these numbers whatever they are, what is the assumed moisture
content of the tree trimmings?

Thanks for taking time to look at this and I appreciate any help this
organization can provide to me.

Richard Nelson

R
Gasification List SPONSORS and ARCHIVES
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From dschmidt at eerc.und.nodak.edu Thu May 6 09:17:05 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733A1@catalina.eerc.und.NoDak.edu>

Approx. (1000 scf)/(1 ton/hr) of wood feed.
Wet wood: 45% moisture
Heating value of gas: 150 btu/scf

Please tell us more about your potential project. Who is involved? and How
big of a plant to you plan on constructing?

-----Original Message-----
From: RICHARD NELSON [mailto:rnelson@oz.oznet.ksu.edu]
Sent: Thursday, May 06, 1999 7:33 AM
To: gasification@crest.org
Subject: GAS-L: Kansas biomass project

Thanks for taking time to look at this and I appreciate any help this
organization can provide to me.

Richard Nelson

R
Gasification List SPONSORS and ARCHIVES
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From mlefcort at compuserve.com Thu May 6 12:23:11 1999
From: mlefcort at compuserve.com (Malcolm D. Lefcort)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <199905061223_MC2-74BE-61C2@compuserve.com>

Richard,

Richard Nelson wrote:

> In Manhattan, Kansas we have a potential biomass project using
> tree trimmings to supply heat either for hot water or to be used in
> conjunction with natural gas at a cement facility. In the latter
> case we are possibly going to need to gasify the biomass which leads
> to my simple questions but ones I had better get expert advice on
> before I proceed any further.

Since tree trimmings are wet (40 to 50% moisture content) and since most
simple, downdraft gasifiers really only work properly on wood waste in the
under 25% moisture content range, why not consider burning the material in
a proper two-stage combustor - which can handle moisture contents of as
high as 65% (wet basis) - and fire your hot water heater, or direct fire
your cement kiln, with 2,000F products of combustion?

Our 2-Stage Heuristic EnvirOcycler (gentle updraft gasification in the
first stage followed by vigorous cyclonic combustion of first stage
producer gas in the second stage) meets particulate levels of 0.05
grains/dry standard cubic foot at 12% CO2 by volume on wood waste as well
as 1 ppm CO and 130 ppm NOx straight out of its 2,000F stack.

The EPA's particulate limit for basic incinerators is 0.08 gr/dscf. Kansas
may have tighter restrictions. Two 45 Million Btu/h earlier versions of
the EnvirOcycler . each cosuming about 6 wet tons/h of wood waste, have
been in continuous operation for 18 years in an oriented strandboard plant
near Bemidji, MN direct firing two rotary dryers.

Malcolm Lefcort
Heuristic Engineering
Vancouver, BC
604-263-8005(t) ,0786(f)

Gasification List SPONSORS and ARCHIVES
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From DMcilveenw at aol.com Thu May 6 14:29:34 1999
From: DMcilveenw at aol.com (DMcilveenw@aol.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <6b9a4231.2463398b@aol.com>

In a message dated 06/05/99 13:19:46 GMT, you write:

<<
Approx. (1000 scf)/(1 ton/hr) of wood feed.
Wet wood: 45% moisture
Heating value of gas: 150 btu/scf

Please tell us more about your potential project. Who is involved? and How
big of a plant to you plan on constructing?
>>
Darren,
When you say 45% moisture - is this on a wet basis or dry basis? Sorry, I'm
never sure.

Regards,
David McIlveen-Wright,
NICERT,
University of Ulster,
Coleraine,
N. Ireland

Gasification List SPONSORS and ARCHIVES
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From dschmidt at eerc.und.nodak.edu Thu May 6 15:23:46 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733A6@catalina.eerc.und.NoDak.edu>

Wet Basis

-----Original Message-----
From: DMcilveenw@aol.com [mailto:DMcilveenw@aol.com]
Sent: Thursday, May 06, 1999 1:30 PM
To: gasification@crest.org
Subject: Re: GAS-L: Kansas biomass project

In a message dated 06/05/99 13:19:46 GMT, you write:

Regards,
David McIlveen-Wright,
NICERT,
University of Ulster,
Coleraine,
N. Ireland

Gasification List SPONSORS and ARCHIVES
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From eeco at eeco.net Thu May 6 15:59:50 1999
From: eeco at eeco.net (EEC)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Burlington, Vermont, biomass gasification information request
Message-ID: <199905061959.PAA22972@solstice.crest.org>

Dear Gasification List Members,

Does anybody have any information, status or performance of the Joseph C. McNeil Generating Station in Burlington Vermont. This high-throughput biomass gasifier project was developed by Battelle Columbus Laboratory and co-funded by DOE and Future Energy Resources Co.

Thanks,
Tomek Rondio
CEO
ENVIRONMENTAL ENGINEERING CORPORATION, (EEC)

ENVIRONMENTAL ENGINEERING CORPORATION, (EEC)
Renewable Energy Division http://www.eeco.net
Pollution Control Division http://www.eeco.net/pollution
E-mail eeco@eeco.net
294 9th Avenue · San Francisco · California · 94118 · USA
TEL (415)386-6424 · FAX (415)386-6484

EEC . . . for a cleaner and healthier natural environment through advanced, cost effective technologies.

From JIRVING104 at aol.com Thu May 6 17:32:12 1999
From: JIRVING104 at aol.com (JIRVING104@aol.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Burlington, Vermont, biomass gasification informationrequest
Message-ID: <680e0a2a.24636308@aol.com>

The Vermont Gasification Project first produced gas in February 1998. It is
located on the site of an existing 50 Mwe combustion biomass plant that has
been operating commercially since 1984.The gasifier project has been in the
process of shakedown and startup. There are several significant
modifications that were deemed necessary to the original design to improve
reliability and operation. The most significant of these changes is a major
modification to the product gas cooling system which is being installed
currently. The plant is scheduled to return to service in mid June. For
questions contact:

John Irving, McNeil Plant Manager
585 PineSt.
Burlington, VT 05401
Phone 802-865-7482
Fax 802-865-7481
email jirving104@aol.com

Gasification List SPONSORS and ARCHIVES
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From arcate at email.msn.com Thu May 6 20:15:11 1999
From: arcate at email.msn.com (Jim Arcate)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Carbotech
Message-ID: <199905070015.UAA09789@solstice.crest.org>

Hello:

Can someone please help me with my charcoal research. I would like to
contact "Carbotech".

They are listed on the EC-ASEAN COGEN site http://www.cogen.ait.ac.th/

Carbotech manufactures charcoal production equipment, specializing
particularly in equipment using wood and sawmill wastes as raw material. The
company has wide experience with projects involving conversion of wastes to
fuel and wastes to energy, working with private and governmental
organizations.

Carbotech Limited, 72 Woodstock Road, Loxley
UK-S6 6TG Sheffield
United Kingdom
TELEPHONE: +44 1142 344932
TELEFAX: +44 1142 344932
CONTACT: Mr. D.W. Kelley

Please give me their e-mail address, web site URL or please refer them to my
web site www.techtp.com

Thank you,
Jim Arcate

PS:FYI see "Charcoal and its Socio-Economic Importance in Asia, Prospects
for Promotion" http://www.rwedp.org/p_charcsocio.html

Gasification List SPONSORS and ARCHIVES
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From Steve.Schuck at bigpond.com Fri May 7 00:50:36 1999
From: Steve.Schuck at bigpond.com (Stephen Schuck)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Burlington, Vermont, biomass gasification information request
Message-ID: <04510992107635@domain0.bigpond.com>

----------
From: EEC <eeco@eeco.net>
To: gasification@crest.org
Subject: GAS-L: Burlington, Vermont, biomass gasification information
request
Date: Friday, 7 May 1999 05:23

Dear Gasification List Members,

Does anybody have any information, status or performance of the Joseph C.
McNeil Generating Station in Burlington Vermont. This high-throughput
biomass gasifier project was developed by Battelle Columbus Laboratory and
co-funded by DOE and Future Energy Resources Co.

Thanks,
Tomek Rondio
CEO
ENVIRONMENTAL ENGINEERING CORPORATION, (EEC)

EEC . . . for a cleaner and healthier natural environment through
advanced, cost effective technologies.

Gasification List SPONSORS and ARCHIVES
http://www.crest.org/renewables/gasification-list-archive

From dan.oconnell at aeat.co.uk Fri May 7 10:34:11 1999
From: dan.oconnell at aeat.co.uk (Dan O'Connell)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Re: Carbotech
Message-ID: <199905071434.KAA10729@solstice.crest.org>

Jim

I have spoken to the company who are not yet on e-mail. They are
happy to receive a fax from you and could arrange an e-mail contact
through a neighbour.

Could you supply all your "snail" co-rdinates and I will forward them
to Mr Kelley if you prefer and they can telephone or fax you.

Dan O'Connell

ETSU, AEA Technology, Harwell, Oxon OX11 0RA UK

______________________________ Reply Separator
_________________________________
Subject: Carbotech
Author: "Jim Arcate" <arcate@email.msn.com> at Internet-mail
Date: 06/05/99 13:27

Hello:

Can someone please help me with my charcoal research. I would like to
contact "Carbotech".

They are listed on the EC-ASEAN COGEN site http://www.cogen.ait.ac.th/

Carbotech manufactures charcoal production equipment, specializing
particularly in equipment using wood and sawmill wastes as raw material. The
company has wide experience with projects involving conversion of wastes to
fuel and wastes to energy, working with private and governmental
organizations.

Carbotech Limited, 72 Woodstock Road, Loxley
UK-S6 6TG Sheffield
United Kingdom
TELEPHONE: +44 1142 344932
TELEFAX: +44 1142 344932
CONTACT: Mr. D.W. Kelley

Please give me their e-mail address, web site URL or please refer them to my
web site www.techtp.com

Thank you,
Jim Arcate

PS:FYI see "Charcoal and its Socio-Economic Importance in Asia, Prospects
for Promotion" http://www.rwedp.org/p_charcsocio.html

The Bioenergy List is sponsored by:
David M. Gubanc.P.E. http://www.gubanc.com and

dk-TEKNIK ENERGY & ENVIRONMENT http://www.dk-teknik.dk
Other SPONSORS and ARCHIVES:

http://solstice.crest.org/renewables/bioenergy-list-archive/

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From arcate at email.msn.com Fri May 7 15:22:17 1999
From: arcate at email.msn.com (Jim Arcate)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Carbotech
Message-ID: <003001be98be$be7fb040$0100007f@localhost>

Hello Dan:

Thank you very much.

As you may know from earlier Gasification & Bioenergy discussions, I am
interested in charcoal for co-firing with coal and use in "CHP& C" Combined
Heat, Power & Charcoal applications.

Rather than limiting my concept to use of the HNEI high yield charcoal
process, I decided to put together info on large-scale charcoal processes
and projects on my web page http://www.techtp.com/biocoal/charcoal.htm

Perhaps Carbotech can look at my web site www.techtp.com and contact me by
e-mail, or air mail me information about their charcoal activities.

I invite others to send me info about charcoal manufacturing processes.

thank you again,

James R. Arcate
3289 Manoa Road Apt A
Honolulu, HI 96822-1273
(808) 988-7502

----- Original Message -----
From: Dan O'Connell <dan.oconnell@aeat.co.uk>
To: <bioenergy@crest.org>; <gasification@crest.org>; Jim Arcate
<arcate@email.msn.com>
Sent: Friday, May 07, 1999 4:34 AM
Subject: GAS-L: Re: Carbotech

Jim

I have spoken to the company who are not yet on e-mail. They are
happy to receive a fax from you and could arrange an e-mail contact
through a neighbour.

Could you supply all your "snail" coordinates and I will forward them
to Mr Kelley if you prefer and they can telephone or fax you.

Dan O'Connell

ETSU, AEA Technology, Harwell, Oxon OX11 0RA UK

Gasification List SPONSORS and ARCHIVES
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From VHarris001 at aol.com Sun May 9 22:32:16 1999
From: VHarris001 at aol.com (VHarris001@aol.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <12754b83.24679efe@aol.com>

Dear Darren,

I assume the figures you quote are from the Camp Lejeune gasifier project? I
notice that your figure of (1000 scf)/(1 ton/hr) of wood feed (at 150 Btu/sq
ft) is approximately half the "rule of thumb" gas generation rate listed in
Tom Reed's "Handbook of Biomass Gasifier Engine Systems" of 2 lb biomass = 2
scfm of gas (or 2000 lbs of biomass = 2000 scfm of gas). I do however see
your estimate is for wood with 45% moisture. as I recall, the Camp Lejeune
project has a fuel dryer prior to the reactor.

Would you attribute the difference to the degree of moisture in the feed (as
I recall, the Camp Lejeune project has a fuel dryer prior to the reactor)?
Or could the difference be a high quantity of tar generation being scrubbed
from the gas prior to testing or consumption in the engine? Do you have any
specific information regarding the amount of tar being removed from the
system? Is the system still operational?

Thanks,
Vernon Harris
VHarris001@aol.com

In a message dated 5/6/99 9:19:46 AM Eastern Daylight Time,
dschmidt@eerc.und.nodak.edu writes:

> Approx. (1000 scf)/(1 ton/hr) of wood feed.
> Wet wood: 45% moisture
> Heating value of gas: 150 btu/scf
>
> Please tell us more about your potential project. Who is involved? and How
> big of a plant to you plan on constructing?
>

-----Original Message-----
From: RICHARD NELSON [mailto:rnelson@oz.oznet.ksu.edu]
Sent: Thursday, May 06, 1999 7:33 AM
To: gasification@crest.org
Subject: GAS-L: Kansas biomass project

Thanks for taking time to look at this and I appreciate any help this
organization can provide to me.

Richard Nelson

Gasification List SPONSORS and ARCHIVES
http://www.crest.org/renewables/gasification-list-archive

From Reedtb2 at cs.com Mon May 10 08:56:07 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <3b6f7fc.24683173@cs.com>

In a message dated 5/9/99 8:36:08 PM Mountain Daylight Time,
VHarris001@aol.com writes:

<<
Dear Vern, Darren et al:

Vern said...

I assume the figures you quote are from the Camp Lejeune gasifier project?
I
notice that your figure of (1000 scf)/(1 ton/hr) of wood feed (at 150 Btu/sq
ft) is approximately half the "rule of thumb" gas generation rate listed in
Tom Reed's "Handbook of Biomass Gasifier Engine Systems" of 2 lb biomass = 2
scfm of gas (or 2000 lbs of biomass = 2000 scfm of gas). I do however see
your estimate is for wood with 45% moisture. as I recall, the Camp Lejeune
project has a fuel dryer prior to the reactor.
>>

Several months ago I said:

RULES OF THUMB:

1 The energy content of typical biomass is 18 MJ/kg (8,000 Btu/lb)
2 Gasification of 1 kg of biomass makes 3 m3 of gas
3 The energy in 1 kg of biomass can generate 5 kWh(thermal) or 1 kWh of
electric power (20% eff)
4 1 m3 of gas weighs 1 kg

Some thumbs are more accurate than others and as we go along, we can remember
the deviations from the above. For #1, lets add "at 10% moisture content.
No. 2 is the most variable ROT

In a paper on "Superficial Velocity" I am preparing for the 4th Biomass
Conference of the Americas (Aug. 29, Oakland) I find that the air fuel ratio
varies from 1.4 to 5.2 as velocity increases from a strongly pyrolytic
gasification with high tar and charcoal to a gasification bordering on
combustion. (In our "Biomass Gasification: Principles and Practice, 1979"
Ray Desrosiers lists 6.36 as the AFR for stoichiometric combustion of wood
and 1.57 as the thermodynamic gasification AFR).

The volume of gas in m3 = AFR + 1 (assuming the molecular weight stays
constant at about 1 kg/m3).

Vern's figure of (1000 scf)/(1 ton/hr) [I assume this is 1000scfm] implies an
air fuel ratio of 2.4, pretty close to the 1.57 of Desrosiers and the
difference could easily be due to "wet fuel", as suggested.

It is amazing how little we know of the science of gasification and how much
we know about what doesn't work very well - ie failed projects.

Keep scrutinizing... TOM REED
BEF

Run # 5 6 8 9
MEASURED VALUES
Air Flow - l/m 4.1 18.8 26.0 46.4
Initial Fuel (g) 89.1 91.1 82.2 84.2
Final Charcoal (g) 11.6 6.8 3.8 0
Condensate (g) 16.7 13.8 11.8 13.8
Tar + Particulate - (g) 2.044 1.463 0.44 0.189
Average Pressure Drop - iwc 0.025 0.11 0.15 0.33
Time of Run 33.5 14.4 9.5 8
Pyrolysis Temp 770 993 1033 1045
Pyrolysis time - min 1.0 1.0 0.6 0.6
DERIVED VALUES
Superficial Velocity - m/s 0.052 0.187 0.260 0.437
Gas Produced - kg (m3) 0.206 0.423 0.387 0.548
Tar, Particulate in Gas - mg/m3 9941 3460 1138 346
Tar - mg/m3 -Filter Method 8330 1330 300 10
Fuel Velocity - cm/min 1.20 2.08 3.16 3.75
Air/Fuel Ratio 1.44 3.80 3.47 5.21
Charcoal Yield - % 13.0% 7.5% 4.7% 0.0%
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From dschmidt at eerc.und.nodak.edu Mon May 10 12:57:06 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733B0@catalina.eerc.und.NoDak.edu>

I filled my answers into your text below.

Dear Darren,

I assume the figures you quote are from the Camp Lejeune gasifier project?
I
notice that your figure of (1000 scf)/(1 ton/hr) of wood feed (at 150 Btu/sq

ft) is approximately half the "rule of thumb" gas generation rate listed in
Tom Reed's "Handbook of Biomass Gasifier Engine Systems" of 2 lb biomass = 2

scfm of gas (or 2000 lbs of biomass = 2000 scfm of gas). I do however see
your estimate is for wood with 45% moisture. as I recall, the Camp Lejeune
project has a fuel dryer prior to the reactor.

Would you attribute the difference to the degree of moisture in the feed (as

I recall, the Camp Lejeune project has a fuel dryer prior to the reactor)?

ans) The number I gave is based on the design of the system at Camp Lejeune.
I rounded the numbers for convenience. It is based on 10% moisture feed.
This design assumption was verified by operational data. It is quite
possible to operate at other conditions and obtain other results. I will
have to run some numbers and review some literature to make any further
comments. I don't dispute Tom's rules of thumb, I'm just providing our
operational data.

Or could the difference be a high quantity of tar generation being scrubbed
from the gas prior to testing or consumption in the engine?

ans) Have to run some numbers and comment later.

Do you have any specific information regarding the amount of tar being
removed from the
system?

ans) The tar content of the gas was less than 150ppm. It was measured
using the filter paper method developed by Agua Das. We continuously
decanted liquids from the process. Many of the light oils carried over with
the water and drained to the sewer. This material was tested and qualified
as non hazardous. The discharge rate was approx. 25 to 50 gallons/hr. The
heavy tar collection rate was very small approx. 1 gal./24 hours operation.

Is the system still operational?
ans) No, but not due to technical difficulties. The project remains under
control of RTI and EPA. RTI's interest is in doing a successful research
project and not continuously running the facility. The property is supposed
to transfer to the military base. They may or may not want to operate the
facility. They would have to put some effort into simplifying the operation
and overcoming some problems that inhibit long term (years) operation. The
project was largely funded by DoD/EPA with very little cost share. The
project was difficult for the interested commercial partner who seems to
have lost interest in ensuring the plant continues to operate as a
showpiece. An important point is that this project was not a failure. Much
information will be documented and many things can be learned form this
experience. There are not many (if any) projects of this scale (1MWe) that
have run for over 100 hours producing electricity on the grid. There are no
documented projects in this size range that have made it as far. I am
referring to wood chip fueled stratified downdraft gasification to a spark
ignited engine generator set. The closest examples are work resulting from
Ankur (Indian company) who have successfully run diesel engines producing
electricity at lower load ranges.

Thanks,
Vernon Harris
VHarris001@aol.com

In a message dated 5/6/99 9:19:46 AM Eastern Daylight Time,
dschmidt@eerc.und.nodak.edu writes:

> Approx. (1000 scf)/(1 ton/hr) of wood feed.
> Wet wood: 45% moisture
> Heating value of gas: 150 btu/scf
>
> Please tell us more about your potential project. Who is involved? and
How
> big of a plant to you plan on constructing?
>

-----Original Message-----
From: RICHARD NELSON [mailto:rnelson@oz.oznet.ksu.edu]
Sent: Thursday, May 06, 1999 7:33 AM
To: gasification@crest.org
Subject: GAS-L: Kansas biomass project

Thanks for taking time to look at this and I appreciate any help this
organization can provide to me.

Richard Nelson

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From arcate at email.msn.com Tue May 11 00:06:11 1999
From: arcate at email.msn.com (Jim Arcate)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Fw: Biomass Power
Message-ID: <000d01be9b63$73e66860$0100007f@localhost>

Hello Bioenergy & Gasification:

Can anyone help me reply to this question ?
Hydrogen rich ? Methanol ?
Thank you, Jim Arcate
-----------------
Jim,

Are you familiar with any systems that recapture carbon from biomass and
produce hydrogen rich fuels?

Daniel

Gasification List SPONSORS and ARCHIVES
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From LINVENT at aol.com Tue May 11 05:04:07 1999
From: LINVENT at aol.com (LINVENT@aol.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Re: Hyrdogen rich fuels
Message-ID: <964891fe.24694c99@aol.com>

In regards to hydrogen rich fuels, methane is certainly hydrogen rich. if he
is thinkin of liquid fuels from biomass there is a lot to be said and many
processes to get there from biomass.

Tom Taylor
Thermogenics Inc.
Gasification List SPONSORS and ARCHIVES
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From snkm at btl.net Tue May 11 07:58:23 1999
From: snkm at btl.net (Peter Singfield)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Fw: Biomass Power
Message-ID: <3.0.32.19990511055903.00e2e154@wgs1.btl.net>

At 06:05 PM 5/10/99 -1000, you wrote:
>Hello Bioenergy & Gasification:
>
>Can anyone help me reply to this question ?
>Hydrogen rich ? Methanol ?
>Thank you, Jim Arcate
>-----------------
>Jim,
>
>Are you familiar with any systems that recapture carbon from biomass and
>produce hydrogen rich fuels?
>
>Daniel
>

Daniel;

Hope the following is what you are looking for. India and Egypt have
numerous gasification of organic wastes to alcohol plants, projects.
Usually using bagasse.

Peter Singfield
Belize, Central America

*****************************************************

URL:http://www.gsfclimited.com/prb02.htm

Oxo synthesis Gas

GSFC's Oxo Synthesis Gas Plant has a rated capacity of 8.65 million
NM3 per annum. The main feed stock is Methane recovered from PGR
Plant and Carbon Dioxide from Ammonia Plants.

Application :

Oxo Synthesis gas is a mixture of Hydrogen 56% and Carbon Monoxide
42% which is used in manufacture of oxo alcohols like Octanol,
Nonanol and Decanol.

Specifications:

H2/CO (Mol ratio) : 1.20 to 1.45
CH4 + N2 + CO2 + Ar : 3.0 % Max.
H2O : Saturated.

For Information Contact:

Mr. Navin Shah, Manager (A&PR)

Gujarat State Fertilizers and Chemicals Limited
P.O. Fertilizernagar Distri. Vadodra. Gujarat, India
Tel. : +91 - 265 - 372451 Fax : +91 - 265 - 372966
email: mail@gsfclimited.com[8]

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From Reedtb2 at cs.com Tue May 11 12:35:45 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <61dc31db.2469b671@cs.com>

Dear Vernon, Daryl et al:

Glad to hear that the Camp LeJeune was a technical success. It is not
surprising that it is not a commercial success in the U.S. with gas at
$2/MMBtu and gasoline at $1/gallon. But it could be a great success in
other places.

Can you tell us when a final report will issue. We might like to stock it
here at the BEF PRESS. While not intended as a research project, it was and
we need to see data or we'll make all the same mistakes over and over...

Glad to see you differentiating between heavy tar and lighter oils. We are
thinking of using two indirect heat exchangers, one in boiling water to
collect the heavy tars, but no water or lighter, followed by a second that
will condense water etc. Comments??

How come we never hear from any of the personnel from the Camp LeJeune
project here on gasification.

Yours truly, TOM REED
BEF

Gasification List SPONSORS and ARCHIVES
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From fkuzel at cglg.org Tue May 11 13:54:53 1999
From: fkuzel at cglg.org (Fred Kuzel)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Great Lakes Biomass Program Solicitation
Message-ID: <000801be9bd8$1d0d3a80$879270d8@Fred.Concentric.net>

NOTICE OF SOLICITATION

The Great Lakes Regional Biomass Energy Program (GLRBEP) has issued a
Request for Proposals for biomass energy projects that encourage the
development and use of biomass energy resources, especially projects located
in the Great Lakes Region.

Funding is available for projects in the following three categories:

1. Projects to Increase the Production or Use of Liquid Biofuels
2. Projects to Increase the Production and Use of Biomass-Derived Gas and
Solid Fuels
3. Projects that Encourage Transfer of Biomass Energy Technology

Total funding available for all projects solicited in 1999 is approximately
$100,000. The maximum funding available for a single project is $50,000.
Matching funds of at least 1:1 are required for all projects. Projects must
be completed within twelve months of funding award. Please note that all
proposals must be submitted by June 4, 1999.

Anyone interested in submitting a proposal must follow the guidelines set
forth in the Request for Proposals (RFP). The RFP is available on the
GLRBEP web site at www.cglg.org/projects/biomass. Copies of the RFP may
also be requested by contacting:

Fred Kuzel or Hadas Lakonishok at: Phone: 312-407-0177
Fax: 312-407-0038
Email: fkuzel@cglg.org

The Great Lakes Regional Biomass Energy Program is one of five Regional
Biomass Energy Programs established and funded by the U.S. Department of
Energy (DOE). The GLRBEP is managed by the Council of Great Lakes
Governors. Seven states participate in the GLRBEP including Illinois,
Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin. The goal of the
GLRBEP is to increase the production and use of biomass energy resources for
economic development and environmental sustainability. Biomass consists of
renewable organic materials and includes forestry and agricultural crops and
residues; wood and food processing wastes; and municipal solid waste (MSW).

Gasification List SPONSORS and ARCHIVES
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From dschmidt at eerc.und.nodak.edu Tue May 11 14:40:27 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733B9@catalina.eerc.und.NoDak.edu>

Darren D. Schmidt, Research Manager
Energy & Environmental Research Center
PO Box 9018
Grand Forks, North Dakota 58202
dschmidt@eerc.und.nodak.edu

I suspect a final report is due within the next 6 months. I will sent
notice.

I think the 2 stage tar removal is a good idea. We had a similar set up at
Camp Lejeune with 2 heat exchangers and 2 liquid separators. However the
discharge from both went straight into a decanter, and I have no way to
prove what density of tar was being condensed. Data was recorded on the
number of discharges from the individual liquid separators, but I do not
suspect that it will be available in the final report.

You probably do not hear from RTI much because they are busy with other
activities outside of biomass. I am the best contact to talk about the Camp
Lejeune project because I was the on site engineer with the project from
start to finish.

Darren D. Schmidt, Research Manager
Energy & Environmental Research Center
PO Box 9018
Grand Forks, North Dakota 58202
dschmidt@eerc.und.nodak.edu

-----Original Message-----
From: Reedtb2@cs.com [mailto:Reedtb2@cs.com]
Sent: Tuesday, May 11, 1999 11:36 AM
To: gasification@crest.org
Subject: Re: GAS-L: Kansas biomass project

Dear Vernon, Daryl et al:

Can you tell us when a final report will issue. We might like to stock it
here at the BEF PRESS. While not intended as a research project, it was and

we need to see data or we'll make all the same mistakes over and over...

How come we never hear from any of the personnel from the Camp LeJeune
project here on gasification.

Yours truly, TOM REED

BEF

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From VHarris001 at aol.com Wed May 12 21:21:19 1999
From: VHarris001 at aol.com (VHarris001@aol.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <ef445e32.246b82dc@aol.com>

Dear Darren, others

Please don't misunderstand my intentions. I'm not trying to disparage the
Camp Lejeune Project. Quite the opposite, I'm interested in the Camp Lejeune
Project because it is identical in nearly every aspect to a project I have in
mind.

However, when I do calculations for sizing the gasifier for 2000 lbs/hr, I
generally arrive at a reactor diameter of about 2 feet (cross-sectional area
of 450 sq in) to achieve minimum tar production and maximum Btu gas for
internal combustion spark ignition engine consumption. As you know, this is
substantially smaller than the Camp Lejeune Gasifier. With a reactor
diameter of 7 feet, it has a cross-sectional area of 5540 sq in, a
cross-section more than 12 times greater that I would anticipate as optimal
sizing.

Concerns about tar output from the Camp Lejeune project were first raised
here by Doug Williams. While I am a rank amateur and much of the chemical
engineering is far beyond my capabilities, what few calculations I have done
regarding my own project leads me to speculate that the Lejeune project
produced considerably less permanent gas and considerably more condensates
and/or char than could be achieved with either a greatly increased gas
production level or a greatly decreased reactor diameter.

While I realize that all factors must be considered before an optimal reactor
sizing can be accomplished, I find it incomprehensible that stratified
downdraft gasification of 2000 lbs/hr of 10% moisture content hogged wood
waste for use in a spark ignition internal combustion engine genset can be
done as suitably in a reactor 7 feet wide as in a reactor 2 feet wide, all
other things held constant. Either my calculations are very far off (which
wouldn't shock me) or the Camp Lejeune reactor can produce a great deal more
gas, and much cleaner to boot!

Was the Camp Lejeune project designed for 1000 scfm gas output or was it
anticipated that the project would be scaled up? I for one would very much
like to see the project run long term and have an opportunity to review the
results. I hope the project is restarted and they have an opportunity to
work with the "superficial velocity" of the project. Perhaps Tom Reed's
paper on the subject could have some influence on the Lejeune project.

Regards,
Vernon Harris

In a message dated 5/10/99 1:00:18 PM Eastern Daylight Time,
dschmidt@eerc.und.nodak.edu writes:

> I filled my answers into your text below.
>
> Dear Darren,
>
> I assume the figures you quote are from the Camp Lejeune gasifier project?
> I
> notice that your figure of (1000 scf)/(1 ton/hr) of wood feed (at 150
Btu/sq
>
> ft) is approximately half the "rule of thumb" gas generation rate listed
in
> Tom Reed's "Handbook of Biomass Gasifier Engine Systems" of 2 lb biomass =
2
>
> scfm of gas (or 2000 lbs of biomass = 2000 scfm of gas). I do however see
> your estimate is for wood with 45% moisture. as I recall, the Camp
Lejeune
> project has a fuel dryer prior to the reactor.
>
> Would you attribute the difference to the degree of moisture in the feed
(as
>
> I recall, the Camp Lejeune project has a fuel dryer prior to the reactor)?
>
> ans) The number I gave is based on the design of the system at Camp
Lejeune.
> I rounded the numbers for convenience. It is based on 10% moisture feed.
> This design assumption was verified by operational data. It is quite
> possible to operate at other conditions and obtain other results. I will
> have to run some numbers and review some literature to make any further
> comments. I don't dispute Tom's rules of thumb, I'm just providing our
> operational data.
>
> Or could the difference be a high quantity of tar generation being
scrubbed
> from the gas prior to testing or consumption in the engine?
>
> ans) Have to run some numbers and comment later.
>
> Do you have any specific information regarding the amount of tar being
> removed from the
> system?
>
> ans) The tar content of the gas was less than 150ppm. It was measured
> using the filter paper method developed by Agua Das. We continuously
> decanted liquids from the process. Many of the light oils carried over
with
> the water and drained to the sewer. This material was tested and qualified
> as non hazardous. The discharge rate was approx. 25 to 50 gallons/hr. The
> heavy tar collection rate was very small approx. 1 gal./24 hours operation.
>
>
> Is the system still operational?
> ans) No, but not due to technical difficulties. The project remains under
> control of RTI and EPA. RTI's interest is in doing a successful research
> project and not continuously running the facility. The property is
supposed
> to transfer to the military base. They may or may not want to operate the
> facility. They would have to put some effort into simplifying the
operation
> and overcoming some problems that inhibit long term (years) operation. The
> project was largely funded by DoD/EPA with very little cost share. The
> project was difficult for the interested commercial partner who seems to
> have lost interest in ensuring the plant continues to operate as a
> showpiece. An important point is that this project was not a failure.
Much
> information will be documented and many things can be learned form this
> experience. There are not many (if any) projects of this scale (1MWe) that
> have run for over 100 hours producing electricity on the grid. There are
no
> documented projects in this size range that have made it as far. I am
> referring to wood chip fueled stratified downdraft gasification to a spark
> ignited engine generator set. The closest examples are work resulting from
> Ankur (Indian company) who have successfully run diesel engines producing
> electricity at lower load ranges.
>
> Thanks,
> Vernon Harris
> VHarris001@aol.com
>
>
>
>
>
> In a message dated 5/6/99 9:19:46 AM Eastern Daylight Time,
> dschmidt@eerc.und.nodak.edu writes:
>
> > Approx. (1000 scf)/(1 ton/hr) of wood feed.
> > Wet wood: 45% moisture
> > Heating value of gas: 150 btu/scf
> >
> > Please tell us more about your potential project. Who is involved? and
> How
> > big of a plant to you plan on constructing?
> >
>
> -----Original Message-----
> From: RICHARD NELSON [mailto:rnelson@oz.oznet.ksu.edu]
> Sent: Thursday, May 06, 1999 7:33 AM
> To: gasification@crest.org
> Subject: GAS-L: Kansas biomass project
>
>
> In Manhattan, Kansas we have a potential biomass project using
> tree trimmings to supply heat either for hot water or to be used in
> conjunction with natural gas at a cement facility. In the latter
> case we are possibly going to need to gasify the biomass which leads
> to my simple questions but ones I had better get expert advice on
> before I proceed any further.
>
> For every one pound or ton of tree trimmings that we gasify in a
> commercial scale gasifier, how many cubic feet of gas can we expect
> to generate and use and what is the Btu content of that gas? Also,
> for these numbers whatever they are, what is the assumed moisture
> content of the tree trimmings?
>
> Thanks for taking time to look at this and I appreciate any help this
> organization can provide to me.
>
> Richard Nelson
Gasification List SPONSORS and ARCHIVES
http://www.crest.org/renewables/gasification-list-archive

From dschmidt at eerc.und.nodak.edu Thu May 13 08:47:45 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733C6@catalina.eerc.und.NoDak.edu>

Thank you for your comments. I suppose I was a bit defensive at first
because of the negative comments that showed on this site prior to the
bioenergy 98' conference.

The reactor was designed for 1100 scfm and was operated mostly at 1000 scfm.
RTI's only involvement in the dimensioning of the gasifier was to verify
cracking rates through packed beds for several organics including naphalene.
Quoting numbers off the top of my head, I remember that naphalene required
approximately 14 feet with the superficial velocity of our gasifier. The
project did rely heavily on the experience of the gasification supplier, who
installed two prior units at this scale and operated them for short periods.
This was Mech-Chem a firm out of Massachusetts. We were sold the idea that
the deep char bed helps to crack tar. This is contrary to Tom Reed's work.
Which proves that thermal destruction must take place to efficiently
decrease tar content. An interesting operational problem/characteristic of
our unit was that we had channelling and hot spots lower in the reactor
which probably contributed to thermal destruction of tars and decreased the
loading of the gas stream. Work needs to be done to determine the smallest
possible vessel that can be constructed and operate effectively.

-----Original Message-----
From: VHarris001@aol.com [mailto:VHarris001@aol.com]
Sent: Wednesday, May 12, 1999 8:20 PM
To: gasification@crest.org
Subject: Re: GAS-L: Kansas biomass project

Dear Darren, others

Please don't misunderstand my intentions. I'm not trying to disparage the
Camp Lejeune Project. Quite the opposite, I'm interested in the Camp
Lejeune
Project because it is identical in nearly every aspect to a project I have
in
mind.

However, when I do calculations for sizing the gasifier for 2000 lbs/hr, I
generally arrive at a reactor diameter of about 2 feet (cross-sectional area

of 450 sq in) to achieve minimum tar production and maximum Btu gas for
internal combustion spark ignition engine consumption. As you know, this is

substantially smaller than the Camp Lejeune Gasifier. With a reactor
diameter of 7 feet, it has a cross-sectional area of 5540 sq in, a
cross-section more than 12 times greater that I would anticipate as optimal
sizing.

regarding my own project leads me to speculate that the Lejeune project
produced considerably less permanent gas and considerably more condensates
and/or char than could be achieved with either a greatly increased gas
production level or a greatly decreased reactor diameter.

While I realize that all factors must be considered before an optimal
reactor
sizing can be accomplished, I find it incomprehensible that stratified
downdraft gasification of 2000 lbs/hr of 10% moisture content hogged wood
waste for use in a spark ignition internal combustion engine genset can be
done as suitably in a reactor 7 feet wide as in a reactor 2 feet wide, all
other things held constant. Either my calculations are very far off (which
wouldn't shock me) or the Camp Lejeune reactor can produce a great deal more

gas, and much cleaner to boot!

Regards,
Vernon Harris

In a message dated 5/10/99 1:00:18 PM Eastern Daylight Time,
dschmidt@eerc.und.nodak.edu writes:

no
> documented projects in this size range that have made it as far. I am
> referring to wood chip fueled stratified downdraft gasification to a
spark
> ignited engine generator set. The closest examples are work resulting
from
> Ankur (Indian company) who have successfully run diesel engines producing
> electricity at lower load ranges.
>
> Thanks,
> Vernon Harris
> VHarris001@aol.com
>
>
>
>
>
> In a message dated 5/6/99 9:19:46 AM Eastern Daylight Time,
> dschmidt@eerc.und.nodak.edu writes:
>
> > Approx. (1000 scf)/(1 ton/hr) of wood feed.
> > Wet wood: 45% moisture
> > Heating value of gas: 150 btu/scf
> >
> > Please tell us more about your potential project. Who is involved?
and
> How
> > big of a plant to you plan on constructing?
> >
>
> -----Original Message-----
> From: RICHARD NELSON [mailto:rnelson@oz.oznet.ksu.edu]
> Sent: Thursday, May 06, 1999 7:33 AM
> To: gasification@crest.org
> Subject: GAS-L: Kansas biomass project
>
>
> In Manhattan, Kansas we have a potential biomass project using
> tree trimmings to supply heat either for hot water or to be used in
> conjunction with natural gas at a cement facility. In the latter
> case we are possibly going to need to gasify the biomass which leads
> to my simple questions but ones I had better get expert advice on
> before I proceed any further.
>
> For every one pound or ton of tree trimmings that we gasify in a
> commercial scale gasifier, how many cubic feet of gas can we expect
> to generate and use and what is the Btu content of that gas? Also,
> for these numbers whatever they are, what is the assumed moisture
> content of the tree trimmings?
>
> Thanks for taking time to look at this and I appreciate any help this
> organization can provide to me.
>
> Richard Nelson
Gasification List SPONSORS and ARCHIVES
http://www.crest.org/renewables/gasification-list-archive
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From dschmidt at eerc.und.nodak.edu Thu May 13 09:00:05 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Camp Lejeune
Message-ID: <601A55066596D211A7AD00104BC6FB250733C7@catalina.eerc.und.NoDak.edu>

Additional comment - to VHarris - make sure you are not using superficial
throat velocities of imbert gasifiers to estimate superficial velocities of
stratified downdraft gasifiers. Here are some factors of gasifier operation
that are difficult to estimate:

How does velocity effect the stratification of reaction zones in the
gasifier?
At what velocity do the gases above the fuel bed continue to flow into the
fuel bed and not escape upward due to convection?
At what velocity does the hot zone migrate down or expand due to heat being
pulled down through the bed and increased reaction rates?
How can channelling and hot spots be best controlled?, and without
significant expense, we have to keep capital costs very low.

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From Reedtb2 at cs.com Fri May 14 08:01:33 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <abee6c42.246d6ab2@cs.com>

Dear Vern, Darren and others:

Vern is asking exactly the right questions about the LeJeune gasifier. All
this sizing of gasifiers is expressed in the single number called
"SUPERFICIAL VELOCITY".

SV = Gas production (Nm3/s)/Cross section at grate or pyrolysis (m3)

The result is calculated in m/s, hence the name. If you don't know gas
production rate, SV can be calculated approx from thruput, since each kg of
biomass generates about 2.5 m3 of gas. SV is a measure of the intensity of
the pyrolysis and gasification reactions in the vessel.

I have long been generally aware of SV as a figure of merit for gasifiers.
In our 1988 "HANDBOOK OF BIOMASS DOWNDRAFT GASIFIER ENGINE SYSTEMS" there is
a table (p 36) of SV for five gasifiers then extant.

The SERI 1 ton/day gasifier (stratified downdraft design, uniform diameter)
was 0.28 and 0.24 m/s on both air and oxygen and was tarry. If we had known
what we know now we would have operated it closer to 1 m/s, 4 ton/day.
When Graboski scaled the SERI gasifier to 25 t/d it had a SV of 5.6 and 3.5
on air and oxygen respectively, outstanding. The Buck Rogers gasifier
operated at 0.13 to 0.23 m/s - and produced lots of tar, easily burned for
heat.

Unfortunately, SV it is ambiguous for WWII Imbert gasifiers with the conical
throat, so two numbers are given, one at the large diameter air inlet where
incoming wood is pyrolysed and some char is gasified, the other at the
pinched throat. The Imbert chosen was 0.63 and 2.5 m/s; the Biomass Corp.
was 0.24 and 0.95 m/s (John Goss - are you lurking out there?)
~~~~~
We are now engaged in further measurements of SV and will present a paper on
the results at the 4th Biomass of the Americas Conference, Aug. 29- Sept. 2
in Oakland, CA. We (Reed, Das, Ellis and Walt) find that SV is the main
control on tar and char production.

We believe that different species of biomass have different SV requirements
in a particular gasifier, depending on the use of the gas. Hard species
(pellets, nut shells, hardwoods) hold together during intense pyrolysis and
can produce very low tar gas, while softer species are carried away by the
gas stream.

We'd certainly appreciate any thoughts and questions on this topic while it's
hot. I would appreciate any data that you can send me on more current
gasifiers, dimensions, thruputs, tar and charcoal production rates. I will
keep them confidential or publish them as you wish. In particular send data
for the Camp LeJeune gasifier and I'll calculate for you. (Is air/fuel ratio
known?)

Yours truly, TOM REED
BEF

In a message dated 5/12/99 7:25:11 PM Mountain Daylight Time,
VHarris001@aol.com writes:

<< Dear Darren, others

Please don't misunderstand my intentions. I'm not trying to disparage the
Camp Lejeune Project. Quite the opposite, I'm interested in the Camp
Lejeune
Project because it is identical in nearly every aspect to a project I have
in
mind.

However, when I do calculations for sizing the gasifier for 2000 lbs/hr, I
generally arrive at a reactor diameter of about 2 feet (cross-sectional area
of 450 sq in) to achieve minimum tar production and maximum Btu gas for
internal combustion spark ignition engine consumption. As you know, this is
substantially smaller than the Camp Lejeune Gasifier. With a reactor
diameter of 7 feet, it has a cross-sectional area of 5540 sq in, a
cross-section more than 12 times greater that I would anticipate as optimal
sizing.

Concerns about tar output from the Camp Lejeune project were first raised
here by Doug Williams. While I am a rank amateur and much of the chemical
engineering is far beyond my capabilities, what few calculations I have done
regarding my own project leads me to speculate that the Lejeune project
produced considerably less permanent gas and considerably more condensates
and/or char than could be achieved with either a greatly increased gas
production level or a greatly decreased reactor diameter.

While I realize that all factors must be considered before an optimal
reactor
sizing can be accomplished, I find it incomprehensible that stratified
downdraft gasification of 2000 lbs/hr of 10% moisture content hogged wood
waste for use in a spark ignition internal combustion engine genset can be
done as suitably in a reactor 7 feet wide as in a reactor 2 feet wide, all
other things held constant. Either my calculations are very far off (which
wouldn't shock me) or the Camp Lejeune reactor can produce a great deal more
gas, and much cleaner to boot!

Was the Camp Lejeune project designed for 1000 scfm gas output or was it
anticipated that the project would be scaled up? I for one would very much
like to see the project run long term and have an opportunity to review the
results. I hope the project is restarted and they have an opportunity to
work with the "superficial velocity" of the project. Perhaps Tom Reed's
paper on the subject could have some influence on the Lejeune project.

Regards,
Vernon Harris
>>
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From dschmidt at eerc.und.nodak.edu Fri May 14 09:04:18 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <601A55066596D211A7AD00104BC6FB250733CF@catalina.eerc.und.NoDak.edu>

The superficial velocity of the Camp Lejeune gasifier is .26 ft/s. The air
flow was not measured. I estimate this from 1100 scfm gas (44% Nitrogen)
flow and 7 ft diameter vessel. This is quite a bit lower than any of the
information published in your handbook. We thought that increasing
residence time would help with tar removal. I have no great data to support
this. The numbers I have for tar and water are as follows - 25 - 50
gallons/hr of total liquids. Heavy tar at 1 gallon/24 hours of operation.
Loading of the gas prior to the engine at a maximum of 150 ppm total
contaminants.

-----Original Message-----
From: Reedtb2@cs.com [mailto:Reedtb2@cs.com]
Sent: Friday, May 14, 1999 7:02 AM
To: gasification@crest.org
Subject: Re: GAS-L: Kansas biomass project

Dear Vern, Darren and others:

Vern is asking exactly the right questions about the LeJeune gasifier. All
this sizing of gasifiers is expressed in the single number called
"SUPERFICIAL VELOCITY".

SV = Gas production (Nm3/s)/Cross section at grate or pyrolysis (m3)

The result is calculated in m/s, hence the name. If you don't know gas
production rate, SV can be calculated approx from thruput, since each kg of

biomass generates about 2.5 m3 of gas. SV is a measure of the intensity of
the pyrolysis and gasification reactions in the vessel.

I have long been generally aware of SV as a figure of merit for gasifiers.
In our 1988 "HANDBOOK OF BIOMASS DOWNDRAFT GASIFIER ENGINE SYSTEMS" there is

a table (p 36) of SV for five gasifiers then extant.

The SERI 1 ton/day gasifier (stratified downdraft design, uniform diameter)
was 0.28 and 0.24 m/s on both air and oxygen and was tarry. If we had known

what we know now we would have operated it closer to 1 m/s, 4 ton/day.
When Graboski scaled the SERI gasifier to 25 t/d it had a SV of 5.6 and 3.5
on air and oxygen respectively, outstanding. The Buck Rogers gasifier
operated at 0.13 to 0.23 m/s - and produced lots of tar, easily burned for
heat.

Unfortunately, SV it is ambiguous for WWII Imbert gasifiers with the conical

throat, so two numbers are given, one at the large diameter air inlet where
incoming wood is pyrolysed and some char is gasified, the other at the
pinched throat. The Imbert chosen was 0.63 and 2.5 m/s; the Biomass Corp.

was 0.24 and 0.95 m/s (John Goss - are you lurking out there?)
~~~~~
We are now engaged in further measurements of SV and will present a paper on

the results at the 4th Biomass of the Americas Conference, Aug. 29- Sept. 2
in Oakland, CA. We (Reed, Das, Ellis and Walt) find that SV is the main
control on tar and char production.

keep them confidential or publish them as you wish. In particular send
data
for the Camp LeJeune gasifier and I'll calculate for you. (Is air/fuel
ratio
known?)

Yours truly, TOM REED

BEF

In a message dated 5/12/99 7:25:11 PM Mountain Daylight Time,
VHarris001@aol.com writes:

sizing.

Concerns about tar output from the Camp Lejeune project were first raised
here by Doug Williams. While I am a rank amateur and much of the chemical
engineering is far beyond my capabilities, what few calculations I have
done
regarding my own project leads me to speculate that the Lejeune project
produced considerably less permanent gas and considerably more condensates
and/or char than could be achieved with either a greatly increased gas
production level or a greatly decreased reactor diameter.

While I realize that all factors must be considered before an optimal
reactor
sizing can be accomplished, I find it incomprehensible that stratified
downdraft gasification of 2000 lbs/hr of 10% moisture content hogged wood
waste for use in a spark ignition internal combustion engine genset can be
done as suitably in a reactor 7 feet wide as in a reactor 2 feet wide, all
other things held constant. Either my calculations are very far off (which

wouldn't shock me) or the Camp Lejeune reactor can produce a great deal
more
gas, and much cleaner to boot!

Was the Camp Lejeune project designed for 1000 scfm gas output or was it
anticipated that the project would be scaled up? I for one would very much

like to see the project run long term and have an opportunity to review the

results. I hope the project is restarted and they have an opportunity to
work with the "superficial velocity" of the project. Perhaps Tom Reed's
paper on the subject could have some influence on the Lejeune project.

Regards,
Vernon Harris
>>
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From tomb at snowcrest.net Sat May 15 21:39:31 1999
From: tomb at snowcrest.net (Tom Blackburn)
Date: Tue Aug 31 21:08:06 2004
Subject: GAS-L: Test Flare Design
Message-ID: <004001be9f3d$16effa80$560466d8@tomblack>

Can anyone out there shed some light concerning the design and usage for
producer gas test flares. Also, I would like to know the flame
characteristics for gas with wood chips as the fuel source.

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From VHarris001 at aol.com Sun May 16 01:36:20 1999
From: VHarris001 at aol.com (VHarris001@aol.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Camp Lejeune
Message-ID: <ae9e4731.246fb364@aol.com>

Dear Darren,

Thanks for the response on the LeJeune sizing, etc. I'll post a few comments
below. Be mindful that I'm only reflecting what I've read or speculated as I
have never even seen a gasifier in operation let alone designed or operated
one.

In a message dated 5/13/99 9:03:54 AM Eastern Daylight Time,
dschmidt@eerc.und.nodak.edu writes:

> Additional comment - to VHarris - make sure you are not using superficial
> throat velocities of imbert gasifiers to estimate superficial velocities of
> stratified downdraft gasifiers.

I am estimating the sizing of the stratified downdraft (co-current flow)
gasifier on the superficial velocity (SV) of the Imbert design. I can't
argue with the great success of the Imbert design in providing gas for spark
ignition consumption. At the same time I agree with Tom Reed that there
doesn't appear to be any particular purpose for either the tuyeres or the
throat in the Imbert. The tuyeres probably help provide intimate mixing of
air/fuel. The throat would increase the SV and slightly change the direction
of the flow of pyrolysis gases through the fuel (providing turbulance). I'm
of the opinion that air/fuel mixing and turbulance are caused by SV and can
be provided by pressure and/or vacuum mechanisms external to the reactor.

Therefore, in stratified downdraft design, I believe elimination of the
tuyeres and throat are correct, however a dramatic reduction of the SV is
quite detrimental, as mixing of optimal air and fuel, along with turbulance
are the primary purpose of the tuyeres and throat. That's the main reason
I'm designing around the Imbert SV. Of course, a secondary reason is that,
just in case I'm dead wrong about all the above, I can always turn down the
SV!

> Here are some factors of gasifier operation
> that are difficult to estimate:

I'd like to give some of my thinking (not original thinking mind you, but
mostly gleaned from outside sources) on the points below. I'd like to hear
your position on these points also!

>
> How does velocity effect the stratification of reaction zones in the
> gasifier?

As I recall, this is based a great deal on the feed rate of the fuel as well
as other factors. The zones can and do move up and down. Some units will
become "top stabilized," that is, the pyrolysis zone moves to the top of the
fuel. Even then, the gasifier operates properly as long as the char bed is
not too deep or clogged with char ash. However, as far as I know, the SV
remains the critical measurement rather than location of the reaction zones.

> At what velocity do the gases above the fuel bed continue to flow into the
> fuel bed and not escape upward due to convection?

This one remains a great mystery to me! The literature is repleat with
illustrations of moisture and pyrolysis gases being driven out the top of a
fuel bed (although I don't recall that any of them were open top stratified
downdraft gasifiers). I can't imagine that moisture would rise through a
substantial downward flow of air into the fuel column. On the other hand, if
the SV were very low, I would think convection could carry mositure and
pyrolysis gases out the top of the bed. Did your design team incorporate
convection calculations and fuel bed depth into the LeJeune unit?

> At what velocity does the hot zone migrate down or expand due to heat being
> pulled down through the bed and increased reaction rates?

First I assume the downward migration of hot zones can go no further than the
grate. Above the grate is ash dust and then char. Above that are the
stratified reaction zones. Tom Reed indicates that although the zones move
around depending on feed and gas generation rates, the pyrolysis temperature
is largely self regulating due to the endothermic nature of pyrolysis itself.
Therefore, if the ash dust and char are removed as they accumulate - and
prior to the system beginning to choke - the pyrolysis zones can move as they
please without affecting the overall reaction. Just be sure to keep the
grate covered with some char or ash for protection.

> How can channelling and hot spots be best controlled?, and without
> significant expense, we have to keep capital costs very low.
>

Like a martini - stirred or shaken. I think this has been one of the most
difficult challenges in reactor design. The SERI unit developed by Tom Reed,
Graboski and Levie used a water cooled stainless steel rake. Most designs
use stirrers, but I think I'm leaning toward shaking for my application - to
avoid jamming in the fuel and the problems of cooling and sealing the
stirrer. I looked at vibratory conveyor designs which I though might shake
and convey ash out at the same time, but I don't believe it will work for my
application.

In his design, Arnt Karlsen used a "sneeze valve" to prevent bridging and an
auger which could operate in reverse, pushing ash back into the reactor (see
the archives).

I doubt any of it can be done very inexpensively, particularly at a large
scale. And each design has it's own drawbacks. However, the alternative of
channeling and hot spots is unacceptable.

Regards,
Vernon Harris
VHarris001@aol.com
Gasification List SPONSORS and ARCHIVES
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From VHarris001 at aol.com Sun May 16 02:02:11 1999
From: VHarris001 at aol.com (VHarris001@aol.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <ec95349d.246fb978@aol.com>

Dear Tom,

Thanks for the results of the superficial velocity tests. As SV increases
toward stoichiometric AFR, the tar content of the gengas has been nearly
depleted. After that point won't the gas begin to lose Btu's? That is to
say, the gas itself will begin to be consumed in the combustion process.
Therefore as SV increases from strongly pyrolytic to stoichiometric, first
wood oil and tar levels decrease as they are converted to permanent gas.
Then at some point (it appears at an AFR of ~5.2), doesn't the permanent gas
begins to decrease as it is combusted? The key is to find the sweet spot,
correct?

Thanks,
Vernon Harris
VHarris001@aol.com

P.S. How can I get a copy of your paper after it is presented?

In a message dated 5/10/99 8:58:52 AM Eastern Daylight Time, Reedtb2@cs.com
writes:

> In a paper on "Superficial Velocity" I am preparing for the 4th Biomass
> Conference of the Americas (Aug. 29, Oakland) I find that the air fuel
ratio
>
> varies from 1.4 to 5.2 as velocity increases from a strongly pyrolytic
> gasification with high tar and charcoal to a gasification bordering on
> combustion. (In our "Biomass Gasification: Principles and Practice,
1979"
>
> Ray Desrosiers lists 6.36 as the AFR for stoichiometric combustion of wood
> and 1.57 as the thermodynamic gasification AFR).
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From Reedtb2 at cs.com Sun May 16 09:27:23 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Re: rice husk study
Message-ID: <b833f310.247021ce@cs.com>

Dear Aliza and all others interested in Rice Hull Energy:

I just talked to Brett Craig at the Louisiana State Ag Center about
availability of the bible of rice husk to energy conversion,

A STUDY OF THE MARKET FOR RICE HUSE-TO-ENERGY SYSTEMS AND EQUIPMENT, (1997).

It is still available for $19.95 from Brett Craig (225, 388 8389 or
bcraig@AGCTR.LSU.EDU) . What a deal! He says please give him your fax
number so he can fax you an order blank. You need to pre-pay.

Yours truly,
TOM REED BEF

>From: Aliza Arlan <AArlan@ormat.com>
>
>Dear Thomas B. Reed,
>
>We saw your announcement on the RICE HUSK BIBLE and would very much like to
>order a copy. However, our e-mail to bcraig@agtr.lsu.edu is being returned.
>Is this the current address or is it just telecomm problems? Thank you for
>your kind help.
>Aliza Arlan aarlan@ormat.com
> >>
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From arnt at c2i.net Mon May 17 01:11:46 1999
From: arnt at c2i.net (Arnt Karlsen)
Date: Tue Aug 31 21:08:07 2004
Subject: ..reactor design philosophy, was: GAS-L: Camp Lejeune, and: GAS-L: Kansas biomass project
In-Reply-To: <ae9e4731.246fb364@aol.com>
Message-ID: <373FA4D9.FA63FAA4@c2i.net>

VHarris001@aol.com wrote:
>
> Dear Darren,
>
> Thanks for the response on the LeJeune sizing, etc. I'll post a few comments
> below. Be mindful that I'm only reflecting what I've read or speculated as I
> have never even seen a gasifier in operation let alone designed or operated
> one.
>
> In a message dated 5/13/99 9:03:54 AM Eastern Daylight Time,
> dschmidt@eerc.und.nodak.edu writes:
>
> > Additional comment - to VHarris - make sure you are not using superficial
> > throat velocities of imbert gasifiers to estimate superficial velocities of
> > stratified downdraft gasifiers.
>
> I am estimating the sizing of the stratified downdraft (co-current flow)
> gasifier on the superficial velocity (SV) of the Imbert design. I can't
> argue with the great success of the Imbert design in providing gas for spark
> ignition consumption. At the same time I agree with Tom Reed that there
> doesn't appear to be any particular purpose for either the tuyeres or the
> throat in the Imbert. The tuyeres probably help provide intimate mixing of

..the tuyeres also provide process control, smaller jets raise air jet
speed, combustion temperature and reactivity. The jets sort of "dig a
tunnel or trench" from the fuel above and into which charred fuel will
fall and combust. Between these "trenches", charred fuel slow down due
to less exposure to heat and the incoming air jets, effectively building
ridges which divert fuel flow into the "trenches".

..these "ridges" vary in size with the exposure to reactivity due to the
fluctations in gas demand, and help control the gasification processes,
to a level acceptable for automotive throttle use, successful WWII
designs used them, we did too.

> air/fuel. The throat would increase the SV and slightly change the direction
> of the flow of pyrolysis gases through the fuel (providing turbulance). I'm
> of the opinion that air/fuel mixing and turbulance are caused by SV and can
> be provided by pressure and/or vacuum mechanisms external to the reactor.

..successful thermochemical gasification require a

1. _thick enough_ , and _tough enough_ combustion zone to heat,
pyrolyse and char the fuel, crack _all_ tars, and heat the

2. _thin enough_ reduction zone to fully reduce combustion gases and
yanking produced gas out of the coal bed before temperature drops to
~950oC, below this, CO and the carbon bed start making CO2 to regain
heat, for details,

3. _appreciate_ the (~400 yrs of gasification experience suggest "check"
doesn't quite cut it ;-)) combined reaction chemistry equivalence
equations involved, these should help you appreciate _what_ is going on
in that hot place...

..design from the gas outlet going upstream, for your first attempts,
shoot for a gas out-of-coal-bed temperature ~950oC at design capasity,
minimize reduction zone thickness, and the gas exposure, or residense,
time in the gasifier, should then wind up somewhere around 10 - 100
milliseconds, if I recall "Gengas" right.

...Imbert and others use sv as a measure of gas going thru the whole
gasifier. In pyrolysis and combustion, time is not critical, but should
be long enough to allow completion.

Reduction is very different, here the _important_ factor, is _gas
exposure_ time in the gasifiers _reduction_ zone, which _I guess_ ,
should wind up somewhere around 3 - 90 milliseconds. See 2. and 3.
above...

..anyone with funds so we can find out?

..the easiest and cheapest way I know of to maximize gas energy content,
is allowing ;-) throttle ash to build up in the gas outlet cage, and
shot for maximum flame speed at the flare head... ;-)

..and _do size_ safety valves and reactor wall thicknesses with safety
in mind, as Onar can testify, we _did_ make _two_ satellite dishes...

> Therefore, in stratified downdraft design, I believe elimination of the
> tuyeres and throat are correct, however a dramatic reduction of the SV is
> quite detrimental, as mixing of optimal air and fuel, along with turbulance
> are the primary purpose of the tuyeres and throat. That's the main reason
> I'm designing around the Imbert SV. Of course, a secondary reason is that,
> just in case I'm dead wrong about all the above, I can always turn down the
> SV!
>
> > Here are some factors of gasifier operation
> > that are difficult to estimate:
>
> I'd like to give some of my thinking (not original thinking mind you, but
> mostly gleaned from outside sources) on the points below. I'd like to hear
> your position on these points also!
>
> >
> > How does velocity effect the stratification of reaction zones in the
> > gasifier?
>
> As I recall, this is based a great deal on the feed rate of the fuel as well
> as other factors. The zones can and do move up and down. Some units will
> become "top stabilized," that is, the pyrolysis zone moves to the top of the
> fuel. Even then, the gasifier operates properly as long as the char bed is
> not too deep or clogged with char ash. However, as far as I know, the SV
> remains the critical measurement rather than location of the reaction zones.
>
> > At what velocity do the gases above the fuel bed continue to flow into the
> > fuel bed and not escape upward due to convection?

..try an internal tar flare, chk my gasifier gif for ideas. Took all our
goo...

..future tweeks will include hi temp steel (first we tried 2" steel
water piping material, which produced ~1mm scale per minute ;-)), an
inlet for CO2 and recycled exhaust gas for temperature control and
process economy, and, some calculation to verify our eyeball
engineering...

..pressurized cold CO2 gas into the tuyeres, the tar flare and fuel feed
is _how_ to do the quickest emergency shotdown possible, 2 minutes, do
_not_ use water, as this will generate CO which, in an emergency, will
_be_ dangerous...

> This one remains a great mystery to me! The literature is repleat with
> illustrations of moisture and pyrolysis gases being driven out the top of a
> fuel bed (although I don't recall that any of them were open top stratified
> downdraft gasifiers). I can't imagine that moisture would rise through a
> substantial downward flow of air into the fuel column. On the other hand, if
> the SV were very low, I would think convection could carry mositure and
> pyrolysis gases out the top of the bed. Did your design team incorporate
> convection calculations and fuel bed depth into the LeJeune unit?
>
> > At what velocity does the hot zone migrate down or expand due to heat being
> > pulled down through the bed and increased reaction rates?
>
> First I assume the downward migration of hot zones can go no further than the
> grate. Above the grate is ash dust and then char. Above that are the
> stratified reaction zones. Tom Reed indicates that although the zones move

..tuyeres will also _fix_ these zones...

> around depending on feed and gas generation rates, the pyrolysis temperature
> is largely self regulating due to the endothermic nature of pyrolysis itself.
> Therefore, if the ash dust and char are removed as they accumulate - and
> prior to the system beginning to choke - the pyrolysis zones can move as they
> please without affecting the overall reaction. Just be sure to keep the
> grate covered with some char or ash for protection.
>
> > How can channelling and hot spots be best controlled?, and without
> > significant expense, we have to keep capital costs very low.

..has anyone of you guys tried combining internal tar flaring, tuyeres
and ash throttling, _without_ an Imbert WWII style steel (or ash) cone
in the reactor?

> Like a martini - stirred or shaken. I think this has been one of the most
> difficult challenges in reactor design. The SERI unit developed by Tom Reed,
> Graboski and Levie used a water cooled stainless steel rake. Most designs
> use stirrers, but I think I'm leaning toward shaking for my application - to
> avoid jamming in the fuel and the problems of cooling and sealing the
> stirrer. I looked at vibratory conveyor designs which I though might shake
> and convey ash out at the same time, but I don't believe it will work for my
> application.
>
> In his design, Arnt Karlsen used a "sneeze valve" to prevent bridging and an
> auger which could operate in reverse, pushing ash back into the reactor (see
> the archives).

..prevent and _cure_, sort of automated _shotgun_ style. In WWII, men
removed bridges with wood sticks, a slag cake from, say, fuzed sewer
sludge pellets, would damage the average WWII style wood stick, so
_rougher_ medicine is needed. And _cheaply_ available... Call it
"sneeze" or "shotgun" valve as you please, to tweak both the linguistic
nuances and the pressurized air dose... ;-)

..my auger also need a small dose of cool purge gas flow to combat air
leaks, this gas is taken from the fan, and also helps carry heat away
from the service gate valve thru the ash it flows thru. _Drawing gas
out_ thru the auger, will also combat air leaks and is less demanding on
dosing pressure, but carry heat closer towards the service gate valve
and out thru the auger.

> I doubt any of it can be done very inexpensively, particularly at a large
> scale. And each design has it's own drawbacks. However, the alternative of
> channeling and hot spots is unacceptable.

..on scaleing up, keep _gas exposure time_ in the _reduction_ zone,
_constant_. Goof there, and you _fail_. (Which means _huge_ gasifiers
would look like _pancakes_ as we learn to control the processes...
;-))

..start small, and _test_ your gear. Doing it on the grid, will help
fund it.
Even in Norway. This will also build a record to show for. Which again
will fund scale-up. Funders will _not_ understand any of the black magic
we preach here.
They _do_ understand big numbers with "$" around them. Show 'em.

--..Arnt

Linux har kule høflige ting som /usr/games/fortune, som her hilser slik:
My message is not that biological determinists were bad
scientists or
even that they were always wrong. Rather, I believe that science must
be
understood as a social phenomenon, a gutsy, human enterprise, not the
work of
robots programmed to collect pure information. I also present this view
as
an upbeat for science, not as a gloomy epitaph for a noble hope
sacrificed on
the alter of human limitations.
I believe that a factual reality exists and that science, though
often
in an obtuse and erratic manner, can learn about it. Galileo was not
shown
the instruments of torture in an abstract debate about lunar motion. He
had
threatened the Church's conventional argument for social and doctrinal
stability: the static world order with planets circling about a central
earth, priests subordinate to the Pope and serfs to their lord. But the
Church soon made its peace with Galileo's cosmology. They had no
choice; the
earth really does revolve about the sun.
-- S.J. Gould, "The Mismeasure of Man"
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From Reedtb2 at cs.com Tue May 18 09:53:44 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Test Flare Design
Message-ID: <12924cf0.2472caff@cs.com>

Dear TOM Blackburn et al:

We have had success running the PG into a vessel (lined with mullite board -
riser sleeve) tangentially close to the bottom. We had an adjustable large
hole at the bottom through which air could flow up as a core to the gas. We
placed a propane torch tangentially above the inlet as a source of ignition.
After a short time and adjustment of bottom air the torch could be removed.

Certainly makes a beautiful flame!

TOM REED
.<<
Can anyone out there shed some light concerning the design and usage for
producer gas test flares. Also, I would like to know the flame
characteristics for gas with wood chips as the fuel source.

Tom C. Blackburn >>
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From Reedtb2 at cs.com Tue May 18 09:53:58 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Kansas biomass project
Message-ID: <93a89499.2472cafd@cs.com>

Dear Vern:

CORRECT: Life has its tradeoffs and so does SV. So far our tests indicate
that the higher the SV, the lower the tar - and the lower the energy content
of the gas. So where is the optimum for minimum cleanup? We're zeroing in
on it.

TOM

Dear Tom,

Thanks for the results of the superficial velocity tests. As SV increases
toward stoichiometric AFR, the tar content of the gengas has been nearly
depleted. After that point won't the gas begin to lose Btu's? That is to
say, the gas itself will begin to be consumed in the combustion process.
Therefore as SV increases from strongly pyrolytic to stoichiometric, first
wood oil and tar levels decrease as they are converted to permanent gas.
Then at some point (it appears at an AFR of ~5.2), doesn't the permanent gas
begins to decrease as it is combusted? The key is to find the sweet spot,
correct?

Thanks,
Vernon Harris
VHarris001@aol.com
>>
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From 146942 at classic.msn.com Sun May 23 12:37:14 1999
From: 146942 at classic.msn.com (skip goebel)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Ammonia in the water
Message-ID: <UPMAIL01.199905011104340328@classic.msn.com>

I still feel that water storage is the answer. One must still think
conventional and yet be able to change gears......
Wouldn't the addition of ammonia to the water make it retain hydrogen and some
esters easier? What about the absorbsion rate of a statically charged gas?

Skip
Sensible Steam

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From uranio at mclink.it Mon May 24 09:15:47 1999
From: uranio at mclink.it (Uranio Mazzanti)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: analytical methods for tar in producer gas
Message-ID: <001101bea5e7$a26f8ac0$c4936ec3@MF3708.mclink.it>

Dear Sirs,
I'm looking for a suitable procedure for
collecting samples of producer gas to be tested for the tar
content.
Can somebody address me to some specific
publications ore can send me the procedure (sampling and
analysis)?
Thank You.
Uranio

From dschmidt at eerc.und.nodak.edu Mon May 24 10:20:10 1999
From: dschmidt at eerc.und.nodak.edu (Schmidt, Darren)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: analytical methods for tar in producer gas
Message-ID: <601A55066596D211A7AD00104BC6FB250733E7@catalina.eerc.und.NoDak.edu>

Contaminant testing for gasifier engine systems A. Das (1989) Biomass
energy Foundation Press 1810 Smith Rd. Golden CO 80401. fax 303 278 0560

-----Original Message-----
From: Uranio Mazzanti [mailto:uranio@mclink.it]
Sent: Monday, May 24, 1999 8:02 AM
To: gasification@crest.org
Subject: GAS-L: analytical methods for tar in producer gas

Dear Sirs,
I'm looking for a suitable procedure for collecting samples of producer gas
to be tested for the tar content.
Can somebody address me to some specific publications ore can send me the
procedure (sampling and analysis)?
Thank You.
Uranio

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From 146942 at classic.msn.com Mon May 24 18:13:57 1999
From: 146942 at classic.msn.com (skip goebel)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: RE: Gas storage in water
Message-ID: <UPMAIL03.199904291325210988@classic.msn.com>

ok then, what if there is a lot of ammonia in the water?
wont that enhance the Hydrogen absorbsion?
skip

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From 146942 at classic.msn.com Mon May 24 20:10:54 1999
From: 146942 at classic.msn.com (skip goebel)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Steam Reforming and CO2
Message-ID: <UPMAIL03.199904291348490723@classic.msn.com>

>>Now here is the question -- would it pay to gasify the balance or simply
increase the boiler capacity and add another steam turbine gen set?
>>
instead of making electricity, would it not be more cost effective to use the
steam as process steam and make value added products?

skip

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From claus_h at image.dk Tue May 25 11:17:34 1999
From: claus_h at image.dk (Claus Hindsgaul)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: analytical methods for tar in producer gas
Message-ID: <01bea691$7b476da0$0a00a8c0@flis.halmfortet.dk>

id FAA27626
Sender: owner-gasification@crest.org
Precedence: bulk
Reply-To: gasification

Uranio,

Do you want to analyze the tar or just determine the amount? Beware that
you will most likely have to define "tar" by the method you use.

I have made some analysis of particles and tar in the gas from a two-stage
gasifier at DTU (w/ separate pyrolysis and gasification). I sampled the
particles isokinetically from the gas stream, on quartz wool filters. These
filters were then extracted with dichloromethane to extract the solubles
("tar"). The mass of sampled particles and the extracted mass could be
determined gravimetrically during the experiments by weighing the filters.
In our case 8-11% of the particle mass was extractable. The tar was
analyzed using open column chromatography and gas chromatography.
My full Master Thesis based on this work is available as a zipped
postscript-file at:
http://www.image.dk/~claus_h/thesis.zip

Later, I have tried other solvents (acetone and anisole) and found, that
both of these extracted at least 50% additional mass ("tar") from the
filters. You may want to try acetone, but it is not as widely used as
dichloromethane. Anisole is a pain to handle due to its high boiling point
and poor available purity (only 99.0% purity is commercially available).

Claus Hindsgaul Hansen
Halmfortet - DTU, Område 120 - DK-2800 Lyngby, Denmark
Phone: (+45) 4525 4174 - FAX: (+45) 4593 5761
claus_h@image.dk
-----Original Message-----
From: Uranio Mazzanti <uranio@mclink.it>
To: gasification@crest.org <gasification@crest.org>
Date: 24. maj 1999 15:29
Subject: GAS-L: analytical methods for tar in producer gas

Dear Sirs,
I'm looking for a suitable procedure for collecting samples of producer gas
to be tested for the tar content.
Can somebody address me to some specific publications ore can send me the
procedure (sampling and analysis)?
Thank You.
Uranio

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From VHarris001 at aol.com Thu May 27 00:19:52 1999
From: VHarris001 at aol.com (VHarris001@aol.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not toTuyere, That Is The Question, was reactor designphilosophy
Message-ID: <a5de7734.247e2202@aol.com>

Dear Arnt, others

I'm still not clear on the reasons - or persuaded by the arguments - for
tuyeres. Check the comments below for my reasoning. Perhaps you or others
can more fully delineate your position and help clarify my understanding of
the need for tuyeres.

In a message dated 5/17/99 1:14:58 AM Eastern Daylight Time, arnt@c2i.net
writes:

> >
> > > Additional comment - to VHarris - make sure you are not using
> superficial
> > > throat velocities of imbert gasifiers to estimate superficial
> velocities of
> > > stratified downdraft gasifiers.
> >
> > I am estimating the sizing of the stratified downdraft (co-current flow)
> > gasifier on the superficial velocity (SV) of the Imbert design. I can't
> > argue with the great success of the Imbert design in providing gas for
> spark
> > ignition consumption. At the same time I agree with Tom Reed that there
> > doesn't appear to be any particular purpose for either the tuyeres or the
> > throat in the Imbert. The tuyeres probably help provide intimate mixing
> of
>
> .the tuyeres also provide process control, smaller jets raise air jet
> speed, combustion temperature and reactivity.

Can't the air jet speed (aka air blast velocity) be raised other than with
tuyeres? Perhaps tuyeres were the best way to raise air jet speed back when
gasifiers were mounted on the back of low compression (and low vacuum) SI
vehicles. However with modern blowers or eductors, surely any desired air
speed through the biomass can be achieved without having to rely on tuyeres?
The increased air speed through the biomass is the critical factor in
increasing temperature and reactivity, rather than the air jet speed from the
tuyere itself, no?

The jets sort of "dig a
> tunnel or trench" from the fuel above and into which charred fuel will
> fall and combust. Between these "trenches", charred fuel slow down due
> to less exposure to heat and the incoming air jets, effectively building
> ridges which divert fuel flow into the "trenches".
>
> .these "ridges" vary in size with the exposure to reactivity due to the
> fluctations in gas demand, and help control the gasification processes,
> to a level acceptable for automotive throttle use, successful WWII
> designs used them, we did too.
>

If I envision it's operation correctly, in the (open top) stratified
downdraft design, the entire cross section of the reactor acts as one single
tuyere. That single tuyere is also the fuel magazine. As gasification
proceeds, the "tunnel or trench" that is dug in the fuel occurs generally
(other than bridging or channeling) in a mostly uniform layer across the
entire cross section of the reactor - rather than in front of the tuyeres -
as in the Imbert style. As reduction occurs, the fuel from above then feeds
into this reactor-wide "tunnel or trench" - depending on the rate of
gasification, the depth of the char ash bed and the fuel feed rate above.
The corresponding "ridge" of fuel would be the fuel in the reactor above.

In summary, my understanding is that the stratified downdraft gasifier
provides high velocity air across the entire reactor cross section -
replacing the primary function of the tuyeres, and forces pyrolysis gases
through all the biomass in the reactor - replacing the primary function of
the constricted hearth.

If I'm off base here, anyone is free to jump in and straighten me out. Doug
Williams, are you still listening? It will save me a lot of effort "doing it
wrong" the first time!

Thanks,
Vernon Harris
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From costich at pacifier.com Thu May 27 09:44:27 1999
From: costich at pacifier.com (Dale Costich)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not toTuyere, That Is The Question, was reactor designphilosophy
Message-ID: <002901bea847$72fbc6c0$dd8d41d8@compaq>

Vern Harris: Since you asked, I'll give my 2 scents worth. The "tuyers" or
a periodic radial placement of air inlet tubes (typ 60 degree increments) re
as in Costich gasifier. is a mute point! When you are constructing the
thing just put them in. They will take a few hours and a few dollars extra
to fit and weld into the design--and then you can use them or not and
decide for yourself if they promote cleaner gas more efficiently.
Additionally, with practice and great care I peer into any of the 6 inlets
on my gasifier to observe the hearth color directly. This provides the
ultimate in judging the reactions at the top of the throat. Good luck, Dale
Costich
-----Original Message-----
From: VHarris001@aol.com <VHarris001@aol.com>
To: gasification@crest.org <gasification@crest.org>
Date: Wednesday, May 26, 1999 9:23 PM
Subject: GAS-L: To Tuyere or Not toTuyere, That Is The Question, was reactor
designphilosophy

>Dear Arnt, others
>
>I'm still not clear on the reasons - or persuaded by the arguments - for
>tuyeres. Check the comments below for my reasoning. Perhaps you or others
>can more fully delineate your position and help clarify my understanding of
>the need for tuyeres.
>
>In a message dated 5/17/99 1:14:58 AM Eastern Daylight Time, arnt@c2i.net
>writes:
>
>> >
>> > > Additional comment - to VHarris - make sure you are not using
>> superficial
>> > > throat velocities of imbert gasifiers to estimate superficial
>> velocities of
>> > > stratified downdraft gasifiers.
>> >
>> > I am estimating the sizing of the stratified downdraft (co-current
flow)
>> > gasifier on the superficial velocity (SV) of the Imbert design. I
can't
>> > argue with the great success of the Imbert design in providing gas for
>> spark
>> > ignition consumption. At the same time I agree with Tom Reed that
there
>> > doesn't appear to be any particular purpose for either the tuyeres or
the
>> > throat in the Imbert. The tuyeres probably help provide intimate
mixing
>> of
>>
>> .the tuyeres also provide process control, smaller jets raise air jet
>> speed, combustion temperature and reactivity.
>
>Can't the air jet speed (aka air blast velocity) be raised other than with
>tuyeres? Perhaps tuyeres were the best way to raise air jet speed back
when
>gasifiers were mounted on the back of low compression (and low vacuum) SI
>vehicles. However with modern blowers or eductors, surely any desired air
>speed through the biomass can be achieved without having to rely on
tuyeres?
>The increased air speed through the biomass is the critical factor in
>increasing temperature and reactivity, rather than the air jet speed from
the
>tuyere itself, no?
>
> The jets sort of "dig a
>> tunnel or trench" from the fuel above and into which charred fuel will
>> fall and combust. Between these "trenches", charred fuel slow down due
>> to less exposure to heat and the incoming air jets, effectively building
>> ridges which divert fuel flow into the "trenches".
>>
>> .these "ridges" vary in size with the exposure to reactivity due to the
>> fluctations in gas demand, and help control the gasification processes,
>> to a level acceptable for automotive throttle use, successful WWII
>> designs used them, we did too.
>>
>
>If I envision it's operation correctly, in the (open top) stratified
>downdraft design, the entire cross section of the reactor acts as one
single
>tuyere. That single tuyere is also the fuel magazine. As gasification
>proceeds, the "tunnel or trench" that is dug in the fuel occurs generally
>(other than bridging or channeling) in a mostly uniform layer across the
>entire cross section of the reactor - rather than in front of the tuyeres -
>as in the Imbert style. As reduction occurs, the fuel from above then
feeds
>into this reactor-wide "tunnel or trench" - depending on the rate of
>gasification, the depth of the char ash bed and the fuel feed rate above.
>The corresponding "ridge" of fuel would be the fuel in the reactor above.
>
>In summary, my understanding is that the stratified downdraft gasifier
>provides high velocity air across the entire reactor cross section -
>replacing the primary function of the tuyeres, and forces pyrolysis gases
>through all the biomass in the reactor - replacing the primary function of
>the constricted hearth.
>
>If I'm off base here, anyone is free to jump in and straighten me out.
Doug
>Williams, are you still listening? It will save me a lot of effort "doing
it
>wrong" the first time!
>
>Thanks,
>Vernon Harris
>Gasification List SPONSORS and ARCHIVES
>http://www.crest.org/renewables/gasification-list-archive
>

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From graeme at powerlink.co.nz Thu May 27 20:31:14 1999
From: graeme at powerlink.co.nz (Graeme Williams)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not toTuyere, That Is The Question, was reactor design philosophy
Message-ID: <000e01bea8a1$0446c360$6ae637d2@graeme>

>Date: Thu, 27 May 1999 00:20:18 EDT
>From: VHarris001@aol.com
>Subject: GAS-L: To Tuyere or Not toTuyere, That Is The Question, was
reactor design philosophy
>
>Dear Arnt, others
>

<snip>

>If I'm off base here, anyone is free to jump in and straighten me out.
Doug
>Williams, are you still listening? It will save me a lot of effort "doing
it
>wrong" the first time!
>
>Thanks,
>Vernon Harris

Dear Vern

Yes, I am still reading the mail, but use my time more productively in the
clinic.

Regarding the discussion on S.V., you more or less have summed it up
correctly in stating the blast velocity covers the whole fuel bed. Ideally
the blast rate should be similar to that of an air nozzle to produce an
incandescent oxidation zone, with a temperature of at least 1200 degreesC.
The only gas exiting this zone will be incandescent CO2, that is of course
if the bed is evenly saturated. CO2 doesn't burn, so a depth of char must
also exist below the oxidation zone to form the reduction zone. This char
goes to the grate, and must be free of ash pockets and clinker or
channelling results. Unfortunately, the concept of an oxidation zone held
between a bed of incoming fuel and a fixed depth reduction zone which must
remain very stable is flawed. At least it is if you need stable gas making.
Oxidation moves towards the incoming air and in doing so increases the
reduction depth resulting in frozen reduction at the grate. Even a movement
of 1 inch will cause change in the reduction zone as the increased char
volume will decrease in temperature and bed resistance. It causes the
reduction bed to fill with fines, and the bed velocity slows down affecting
the oxidation temperature.

So in order to keep the oxidation zone fixed in these open core gasifiers,
grate movement usually removes charcoal from the reduction zone and in the
process disturbs the reduction bed reactions and the quality of the
resulting gas.

If you wanted to overcome this problem, your gasifier would need a grate, a
depth of charcoal about 12 inches, and a rotating sprinkle head to add the
fuel evenly and continuously to the top of the char bed. The blast rate
should be impinging directly onto the char and not filter through the actual
fuel mass. The depth of char depends on the fuel size, smaller being
shallower and larger deeper. Use a manometer on the outlet and adjust the
fuel flow to maintain an even pressure, and of course a gas quality that
burns.

For the record, high S.V. only increases the oxidation temperature which in
turn increases the volume of CO2. If the gas has poor C.V. then its because
there is insufficient char available for reduction, and you have oxidation
too near the grate. This is also the reason for burnt grates as any steel
in contact with oxidising char will melt.

It is important to remember you cannot have ash accumulating at the grate
and if you do, then you are combusting fuel rather than gasifying it. Fine
ash should be exiting the grate with the gas.

Hope this clears the way for you to proceed.

Regards

Doug Williams.

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From arnt at c2i.net Fri May 28 19:28:37 1999
From: arnt at c2i.net (Arnt Karlsen)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not to Tuyere, That Is The Question; long...
In-Reply-To: <a5de7734.247e2202@aol.com>
Message-ID: <374F2660.508A261A@c2i.net.>

VHarris001@aol.com wrote:
[...]
> I'm still not clear on the reasons - or persuaded by the arguments - for
> tuyeres. Check the comments below for my reasoning. Perhaps you or others
> can more fully delineate your position and help clarify my understanding of
> the need for tuyeres.
>
> In a message dated 5/17/99 1:14:58 AM Eastern Daylight Time, arnt@c2i.net
> writes:
[...]
> > .the tuyeres also provide process control, smaller jets raise air jet
> > speed, combustion temperature and reactivity.

..here is where I could have added "mechanical fuel particle size
reduction and fuel feed agitation, process zone control, tunneling
closure and precise combustion air metering", problem is we also used an
ash throat, a sort of caged ash throttle grate and a fuel hopper flare,
so I havent really verified these buzzwords myself...

> Can't the air jet speed (aka air blast velocity) be raised other than with
> tuyeres? Perhaps tuyeres were the best way to raise air jet speed back when
> gasifiers were mounted on the back of low compression (and low vacuum) SI
> vehicles. However with modern blowers or eductors, surely any desired air
> speed through the biomass can be achieved without having to rely on tuyeres?

..sure. Now reviewing the governing chemistry involved, you will learn
you increase syngas yield by keeping the reactor vessel pressure as
_low_ as possible, which will harm combustion. There are other dirty
tricks such as feeding oxygen, propane or syngas flaring, _grinding and
metering_ the fuel feed or use a multi stage reactor system.

You will want to _precisely_ control the reduction zone conditions, you
want to keep it hot _enough and at a low enough_ pressure to maximize
syngas yield.
The _cost-effective_ way to do this is tuyeering, which can be tweaked
minimizing air feed, maximizing air jet speed, and recycling exhaust gas
thru 'em.

..the Swedish WWII K¨alle charcoal pellet gasifier recycled ~18% engine
exhaust gas into gasifier air, this cut fuel flow by ~25%, recycling was
needed to avoid reactor piping melt down...

..if you find a more cost-effective way to do this than tuyeering,
patent it!

> The increased air speed through the biomass is the critical factor in
> increasing temperature and reactivity, rather than the air jet speed from the
> tuyere itself, no?
>
> > The jets sort of "dig a
> > tunnel or trench" from the fuel above and into which charred fuel will
> > fall and combust. Between these "trenches", charred fuel slow down due
> > to less exposure to heat and the incoming air jets, effectively building
> > ridges which divert fuel flow into the "trenches".
> >
> > .these "ridges" vary in size with the exposure to reactivity due to the
> > fluctations in gas demand, and help control the gasification processes,
> > to a level acceptable for automotive throttle use, successful WWII
> > designs used them, we did too.
> >
>
> If I envision it's operation correctly, in the (open top) stratified
> downdraft design, the entire cross section of the reactor acts as one single
> tuyere. That single tuyere is also the fuel magazine. As gasification

..no. This (otsd) consept can be compared to your grand-dads tobacco
pipe; it will glow at the top because the combustion process is starved
for fuel and air at the same time, "trying to get air, it crawls _out_
of the fuel". Grand-dad survived the CO gas because the reduction zone
was starved for heat and died of cancer because of tar tunneling... ;-)

> proceeds, the "tunnel or trench" that is dug in the fuel occurs generally
> (other than bridging or channeling) in a mostly uniform layer across the
> entire cross section of the reactor - rather than in front of the tuyeres -
> as in the Imbert style. As reduction occurs, the fuel from above then feeds

.._no_. As fuel is part _burned_ away, and part _drawn_ away by charcoal
consumed by reduction.
The otsd will require _precise sprinkling_ of _ground to size_ and
charred fuel, or charring the fuel on top of the glowing bed with a
support flare to match my, or K¨alle or Imbert's gasifier performances.

> into this reactor-wide "tunnel or trench" - depending on the rate of
> gasification, the depth of the char ash bed and the fuel feed rate above.
> The corresponding "ridge" of fuel would be the fuel in the reactor above.

..right on ;-). Problem is, how do you make _sure_ it is charred? We
dont wanna kill down stream engines or grand-dads thru tar tunnelling,
do we?

> In summary, my understanding is that the stratified downdraft gasifier
> provides high velocity air across the entire reactor cross section -
> replacing the primary function of the tuyeres, and forces pyrolysis gases
> through all the biomass in the reactor - replacing the primary function of
> the constricted hearth.

..IMHO, the primary _two_ tuyere functions are:
1. fix the combustion zone to a certain level
2. agitate and torch the combustion zone to a certain thickness

..IMHO, the primary _two_ throat (constricted hearth) functions are:
1. fix the reduction zone to a certain level
2. fix the reduction zone to a certain thickness

> If I'm off base here, anyone is free to jump in and straighten me out. Doug
> Williams, are you still listening? It will save me a lot of effort "doing it
> wrong" the first time!

Doug Williams wrote:

> Regarding the discussion on S.V., you more or less have summed it up
> correctly in stating the blast velocity covers the whole fuel bed.

..however, imho there is much confusion around these theoretical
numbers. I prefer to look at numbers measured at the gasifier _throat_,
which will give us the optimum performance numbers, and design from
there.

> Ideally
> the blast rate should be similar to that of an air nozzle to produce an
> incandescent oxidation zone, with a temperature of at least 1200 degreesC.
> The only gas exiting this zone will be incandescent CO2, that is of course

..and H2O...we also produce H2, remember... ;-)

> if the bed is evenly saturated. CO2 doesn't burn, so a depth of char must
> also exist below the oxidation zone to form the reduction zone. This char
> goes to the grate, and must be free of ash pockets and clinker or
> channelling results.

..our's wasnt ;-), we used ash for heat insulation and gas outlet
throttling, _way_ overkill, but neat to control reduction zone
thickness. I agree _pockets_ in the char flow here, is bad.

> Unfortunately, the concept of an oxidation zone held
> between a bed of incoming fuel and a fixed depth reduction zone which must
> remain very stable is flawed. At least it is if you need stable gas making.

..IMHO, the above are _requirements_, to comply, these must forcefully
be _held_ stable, by tuyeering or fuel sprinkling, ash throttling, etc.
More on Grand-dad's pipe below --->

> Oxidation moves towards the incoming air and in doing so increases the
> reduction depth resulting in frozen reduction at the grate. Even a movement
> of 1 inch will cause change in the reduction zone as the increased char
> volume will decrease in temperature and bed resistance. It causes the
> reduction bed to fill with fines, and the bed velocity slows down affecting
> the oxidation temperature.
>
> So in order to keep the oxidation zone fixed in these open core gasifiers,
> grate movement usually removes charcoal from the reduction zone and in the

..ideally, all charcoal in this zone is consumed reducing CO2 into CO...

> process disturbs the reduction bed reactions and the quality of the
> resulting gas.
>
> If you wanted to overcome this problem, your gasifier would need a grate, a
> depth of charcoal about 12 inches, and a rotating sprinkle head to add the

..with a 4" throat diameter, built inside a 14" pipe 3 feet tall. Place
the 7 10-13mm tuyeres ~6" above the throat, and the tar flare 12-16"
above the throat. If memory serves, my ash throttle grate moved some 8"
up and down inside the gas outlet cage, giving an effective reduction
zone thickness between 8 and 16". Stick the auger into a standard T-pipe
spool and flange it in between the gasifier and the full bore service
gate valve.

..going the otsd route in 12" pipe spool to an oil barrel, I'd sprinkle
to maintain a 14-16" total ie: combustion ~2-4" + reduction ~10-12", on
full bore operation, and let it sink to 6-10" (1-2"+ 5-8") on "idle" for
my first trials. Then I'd probably shove in the piping to make it a
K¨alle...

> fuel evenly and continuously to the top of the char bed. The blast rate
> should be impinging directly onto the char and not filter through the actual
> fuel mass. The depth of char depends on the fuel size, smaller being
> shallower and larger deeper. Use a manometer on the outlet and adjust the
> fuel flow to maintain an even pressure, and of course a gas quality that
> burns.

..we used clear plastic waterfilled hoses to find 2 meters of suction...
;-)

> For the record, high S.V. only increases the oxidation temperature which in
> turn increases the volume of CO2. If the gas has poor C.V. then its because
> there is insufficient char available for reduction,

..or _too much_, causing _re_-oxidation; CO -> C + CO2 + heat,
temperature will then fall _well_ below the ideal 950oC, higher
temperatures on poor gas may also point to air leaks into the gasifier.
> and you have oxidation
> too near the grate. This is also the reason for burnt grates as any steel
> in contact with oxidising char will melt.

..note that stainless steels, titanium etc, _will corrode_ in our dusty
hot reducing environments, their corrosion protection rely on _surface_
oxygen diffusing into the metal, I was quoted a 10 minute service life
on some top priced titanium piping, we use cheap heat resistant mild
steel...

> It is important to remember you cannot have ash accumulating at the grate
> and if you do, then you are combusting fuel rather than gasifying it. Fine
> ash should be exiting the grate with the gas.

..assuming traditional grate design. My multi purpose ash grate seem to
collect most of the ash, we use it for throttling, heat shielding, and
slag removal. When we ran our mower engined flare fan on pelletized
sewer sludge, we also produces slag pellets which came out nicely thru
the auger. If left sitting in the gasifier long enough without forced
bed movement by ash augering, the sewer sludge pellets will fuze into
cakes.

> Hope this clears the way for you to proceed.

--
..Arnt ..to bypass my spam filter: cut ".no" in my address... ;-)
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From buitn at hcm.vnn.vn Sat May 29 09:52:41 1999
From: buitn at hcm.vnn.vn (Bui Tuyen)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not toTuyere, caution for looking through air inlets
Message-ID: <19990529135339.AAA10700@4rgroup>

Dear Vern et al:
Indeed one can learn a lot by observing the hearth color, looking through
an air inlet. Like Dale said, great care must be taken: always have
something to protect your face, eyes
specially, just in case of unforeseeable "sneeze".
Tuyen.

> Vern Harris: Since you asked, I'll give my 2 scents worth. The "tuyers"
or
> a periodic radial placement of air inlet tubes (typ 60 degree increments)
re
> as in Costich gasifier. is a mute point! When you are constructing the
> thing just put them in. They will take a few hours and a few dollars
extra
> to fit and weld into the design--and then you can use them or not and
> decide for yourself if they promote cleaner gas more efficiently.
> Additionally, with practice and great care I peer into any of the 6
inlets
> on my gasifier to observe the hearth color directly. This provides the
> ultimate in judging the reactions at the top of the throat. Good luck,
Dale
> Costich

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From Reedtb2 at cs.com Sun May 30 17:13:40 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: Re: FW: Products of Wood Pyrolysis
Message-ID: <b12edf3e.2483042c@cs.com>

Dear Harry et al:

Long time no E. The products of wood pyrolysis are truly amazing - and
possibly valuable. At present there are dozens of labs around the world
trying to commercialize "fast pyrolysis" of wood which converts wood to a
liquid with ~ 65% mass efficiency.

I visited Prof. David Othmer, author of the Encyclopedia of Chemical
Technology in 1977 when I first went to SERI/NREL. He gave the same advice
as you do. He had dozens of patents in this field and made lots of money,
but by 1950 the last wood pyrolysis to chemicals plant had shut down because
most of the products could be produced more easily from CHEAP oil.

However, there may not always be CHEAP oil and someday some of these products
may again be valuable. At present about the only pyrolysis product on the
market is liquid smoke for barbecues. In fact NOT getting pyrolysis oils and
tars is the main problem in wood gasification.

However, pyrolysis is a necessary precursor to both gasification and
combustion, so I do my best to understand it and use it to advantage.

Yours truly,
TOM REED

<<
Hello all,

There are perhaps thousands of products from wood pyrolysis, counting
the isomers. Having pyrolyzed wood there are two exceedingly difficulty
activities are ahead ---

<1> Identifying particular products having of unique and proven market
value.

<2> Separating, purifying and marketing thoseproducts to commercial
standards for a reasonable cost.

Wood alcohol was the early example of a wood pyrolysis product that
totally lost. It is now methyl alcohol that is now a commodity
petrochemical.

Wood pyrolysis is a looser. I tried it with manure and gained a lot of
experience that I am sharing with you all right now.

Harry

<><><><><><><><><><><><><><><><><><><><><><><><><><><>

Harry W. Parker, Ph.D., P.E.
>>
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From arnt at c2i.net Mon May 31 05:33:31 1999
From: arnt at c2i.net (Arnt Karlsen)
Date: Tue Aug 31 21:08:07 2004
Subject: GAS-L: To Tuyere or Not toTuyere, caution for looking through air inlets
In-Reply-To: <19990529135339.AAA10700@4rgroup>
Message-ID: <37525730.9765BF70@c2i.net.>

Bui Tuyen wrote:
> Dear Vern et al:
> Indeed one can learn a lot by observing the hearth color, looking through
> an air inlet. Like Dale said, great care must be taken: always have
> something to protect your face, eyes
> specially, just in case of unforeseeable "sneeze".
> Tuyen.

..I _knew_ I forgot to mention something, this above.

..the final obvious use of tuyeres, is of cource to stick in an
oxy-acetylene welding torch thru one or more tuyeres to light up the
gasifier, or if you like electrics, a music wire thru two and the coal
bed, (chk for shorting) and hook up the power. Automation would require
some form of tuyere manifold into which heated air could be piped, and
fed thru both an electric heat gun or the above torch (big lean flame
for hot O2) for light up, and recycling heat from hot air from the
reactors external surfaces inside some heat shield casing.
Plenty neat ways to do things...

--
..Arnt ..to bypass my spam filter: cut ".no" in my address... ;-)
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BioEnergy Lists: Gasifiers & Gasification

May 1999 Gasification Archive