[Terrapreta] Commercial charcoal VM content

[Tom Miles]

Michael,

The charcoal is right in the reduction zone so it's probably a low VM char.
Depending on how you run the gasifier you can pull off the charcoal before
it is completely reduced. Typical small scale gasifiers that are well run
generate about 2-3% char. A poorly run gasifier can make 10% char. So a 10
kWe gasifier using 1.4 kg/kW will make about 8 kg char in a six hour day.
(1.4 g x 10 kW x 6 hr x 10%).In India and Cambdia they are running 5-6 hours
per day. 

One gasifier here has a long vertical bed of char below an open core
gasifier.It appears that tars from the gasification are recondensing on the
deep char bed because the gas coming out is pretty clean (no benzene). I
would think that the char would have a high VM content.

The point is that reactors can be run to generate different qualities of
char. There are probably appropriate uses for each quality of char. 

Tom        

-----Original Message-----
From: Michael J Antal [mailto:mantal at hawaii.edu] 
Sent: Sunday, March 11, 2007 7:35 PM
To: Tom Miles
Cc: 'Tom Miles'; 'Jdeenik at Hawaii. Edu'; terrapreta at bioenergylists.org; 'Goro
Uehara'
Subject: Re: RE: [Terrapreta] Commercial charcoal VM content

Hi Tom: if this charcoal is a result of gasification by CO2 (the Boudouard
reaction), then it must be a very low VM char with a surface area in excess
of 500 m2/g (maybe close to 1000 m2/g).  As you know, neither thermodynamics
nor kinetics favor the Boudouard reaction at temperatures below about 800 C.

On the other hand, maybe it is secondary char that forms from the pyrolysis
of the tarry vapors.  In this case its surface area could be much lower, and
its VM content higher. 

Michael.

----- Original Message -----
From: Tom Miles <tmiles at trmiles.com>
Date: Saturday, March 10, 2007 10:51 am
Subject: RE: [Terrapreta] Commercial charcoal VM content
To: 'Tom Miles' <tmiles at trmiles.com>, "'Michael J. Antal, Jr.'"
<mantal at hawaii.edu>
Cc: "'Jdeenik at Hawaii. Edu'" <jdeenik at hawaii.edu>,
terrapreta at bioenergylists.org, 'Goro Uehara' <goro at hawaii.edu>

> I continue to question drawing a correlation between reactor 
> temperature and charcoal quality without also quantifying the volatile 
> matter (VM) content.
> 
> 
> 
> When we gasify wood in a  down draft gasifier we find two types of 
> char in
> the bed . The first is a hard shiny char that we find produced 
> near the
> oxidation zone. The second, we call it "reduction char", is a 
> porous puffy
> char that is in the reduction zone where the CO2 produced from 
> oxidationreacts with char to produce combustible gas. It has been 
> subjected for a
> short time to gases that start at  1000 C and are cooled by 
> reaction with
> the char to 600C.  This reduction char is puffy, porous, and low 
> density,with a visible swelled structure. I don't know what the 
> volatile matter is
> for this reduction char but I would guess that it would be very 
> low.  It can
> be produced as a byproduct of gasification to produce power for rural
> communities. Is this char any good for crops? We need VM data.
> 
> 
> 
> Tom
> 
> 
> 
> See:
> 
>
http://www.fluidynenz.250x.com/_framed/250x/fluidynenz/IrelandJune2005/IMG_1
> 255.jpg
> 
> 
> 
> 
> 
>  
> 
> 
> 
> From: terrapreta-bounces at bioenergylists.org
> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Tom Miles
> Sent: Thursday, March 08, 2007 6:18 AM
> To: thomas.beer at clorox.com; 'Michael J. Antal, Jr.'
> Cc: terrapreta-bounces at bioenergylists.org; 'Jdeenik at Hawaii. Edu';
> terrapreta at bioenergylists.org; 'Goro Uehara'
> Subject: Re: [Terrapreta] Commercial charcoal VM content
> 
> 
> 
> Thomas,
> 
> 
> 
> Can you give us a range of typical VM and ash characteristics of 
> your char
> in? Is the analysis Michael reported typical?
> 
> 
> 
> Can you make a 20% volatile char (approximate max temp 400-450 C) 
> on order?
> What minimum quantities?
> 
> 
> 
> What is the typical ash content of the char before it gets blended?
> 
> 
> 
> Do you have typical analyses of ash compositions (K, NA, CaO, Mg, 
> P, etc.)
> 
> 
> 
> Thanks
> 
> 
> 
> Tom Miles
> 
> 
> 
> 
> 
> 
> 
> 
> 
> From: thomas.beer at clorox.com [mailto:thomas.beer at clorox.com] 
> Sent: Thursday, March 08, 2007 5:45 AM
> To: Michael J. Antal, Jr.
> Cc: Goro Uehara; Jdeenik at Hawaii. Edu; terrapreta at bioenergylists.org;
> terrapreta-bounces at bioenergylists.org; Tom Miles
> Subject: Re: [Terrapreta] Commercial charcoal VM content
> 
> 
> 
> 
> Hi Folks: 
> Remember that Kingsford is offering the pure  wood char... before 
> it is
> combined with other ingredients and a binder to make a briquette. 
> The size
> of this material is typically 1/4" and below, with a few thin (1/8-
> 1/4")chips up to 1/2" across. These are what make it through our 
> millingprocesses. 
> Volatile content, ash, particle size, ignition temperature, 
> moisture are all
> specified. 
> Let me know your interest and I'll connect you with a contact within
> Kingsford. 
> 
> Thomas Beer
> Manufacturing Technology
> Clorox Services Company
> 3900 Kennesaw 75 Parkway, Suite 100
> Kennesaw, GA   30144
> 770-426-2419
> 770-426-2428- FAX
> 770-364-1079- Cell 
> 
> 
> "Michael J. Antal, Jr." <mantal at hawaii.edu> 
> Sent by: terrapreta-bounces at bioenergylists.org 
> 
> 03/07/2007 09:15 PM 
> 
> 
> To
> 
> Tom Miles <tmiles at trmiles.com>, terrapreta at bioenergylists.org 
> 
> 
> cc
> 
> "Jdeenik at Hawaii. Edu" <jdeenik at hawaii.edu>, Goro Uehara 
> <goro at hawaii.edu> 
> 
> 
> Subject
> 
> [Terrapreta] Commercial charcoal VM content
> 
> 
> 
>        	
> 
> 
> 
> 
> Hi Tom: thanks for your very informative posting.
> 
> Readers of Energy & Fuels may recall an article from my lab "High-
> YieldBiomass Charcoal" (Vol. 10, No. 3, 1996, pp. 652-658) that 
> lists the
> following proximate analyses of commercial barbeque charcoals:
> 
> Kingsford briquette                  36.4% VM                 
> 17.2%  ash
> Kiawe lump charcoal                 28.3% VM                 
> 01.96% ash
> Mesquite lump charcoal                  9.0% VM                 
> 04.17% ash
> 
> The very high VM content of the Kingsford briquette charcoal makes 
> it easy
> to ignite.  The mesquite charcoal is tough to ignite.
> 
> Best wishes, Michael.
> 
> -----Original Message-----
> From: Tom Miles [mailto:tmiles at trmiles.com]
> Sent: Wednesday, March 07, 2007 8:10 AM
> To: 'Michael J. Antal, Jr.'; terrapreta at bioenergylists.org
> Subject: RE: [Terrapreta] Charcoal properties II
> 
> 
> 
> All,
> 
> Michael wrote:
> 
> "Since well-characterized charcoal samples are not easily 
> available, I
> suggest that you document everything you know (e.g. its source, the
> feedstock, its history, etc.) about the sample you are testing, 
> and that you
> set aside a small sub-sample of the charcoal (ca. 100 g or more) 
> for later
> testing in the event that you find the charcoal to be particularly
> beneficial (or detrimental) to plant growth.  Without well-
> characterizedcharcoal samples, progress can still be made if the 
> charcoals that prove to
> be particularly beneficial (or detrimental) can be identified and 
> testedafter the fact."
> 
> If the volatile matter content is the distinguishing 
> characteristic of the
> charocal then we can use that as a reference. The Ash and Moisture 
> Contentwould also be a product of the proximate analysis.
> 
> I uploaded a post to the Terra Preta site called "Factors Influencing
> Charcoal Quality" that I posted to the biomass cooking stoves site 
> lastyear.
> http://terrapreta.bioenergylists.org/charcoalquality
> If a target quality is 20%-25% volatile matter then the heat treat
> temperature for the wood samples cited would be about 400-450 C 
> for about an
> hour. I understand that commercial charcoals contain about 14% 
> volatilematter.
> 
> Charcoals used in the Indonesia work by the Forestry Research and
> Development Agency and the Japan International Cooperation Agency 
> using a
> flat kiln were tested at 20-25% volatile matter (VM) and 4%-6% 
> ash. See:
> "A Flat kiln and Utlization of Sawdust Charcoal"
> http://terrapreta.bioenergylists.org/?q=node/124
> And
> "Trials on Some of Charcoal Production Methods for Carbon 
> Sequestration in
> Indonesia Kazuya Ando, Nobuo Ishibashi, Gustan Pari, Kiyoshi 
> Miyakuni 2004"
> http://www.georgiaitp.org/carbon/PDF%20Files/Posters/AndoPoster.pdf
> 
> Other chemical properties that I see tested are: pH, Cation Exchange
> Capacity (me/100g), Exchangeable cations (me/100g) K, Ca, Mg, Na, and
> probably available phosphate.
> 
> I'm sure that organizations like Cornell have databases of these 
> qualitiesand a good notion of how charcoal quality impacts plant 
> response in soils.
> 
> What values do we have for lump charcoal purchased in stores for 
> barbecue,"horticultural charcoal" or other common sources. I'm 
> sure that producers
> like Kingsofrd/Chlorox could produce the quality of charcoal 
> required by the
> truckload.
> 
> Tom Miles
> 
> 
> 
> 
> 
> 
> 
> 
> 
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