[Gasification] Autopyrolysis Biochar

Otto Formo terra-matricula at hotmail.com
Wed Dec 25 14:24:46 CST 2013

Dear Tom R,
I like your, "AutoChar", far better, than the TLUD char.
TLUD is more of a discription of how the fire is lit (from the top) and how the Natural Draft works, namely Upwards.
The most important issue here, I find from your writings,  is how the biomass is lit, namely from the top.
I am happy to  see how well the "Peko Pe" fit to your "AutoChar" consept.
You will not even need a wet newspaper to block the flame to consume the char........:)
When the flame is gone and the gases consumed, your Bio-char is served and ready for use. (20-25%?)
Like using a Microwave, just start it and when its ready, the Peko Pe will also "stop" according to lack of flame.
The Peko Pe is tuned from "factory", to  fit "standard" settings as well...............:)
Happy Holydays to all of you.
Best wishes
From: tombreed2010 at gmail.com
Date: Tue, 24 Dec 2013 17:02:57 -0500
To: gasification at lists.bioenergylists.org; deankstill at gmail.com
Subject: [Gasification] Autopyrolysis Biochar

Dear Tom Miles and all
(Be sure to specify Miles or Reed when addressing these two Toms specifically)
I regularly make what I have come to call "AUTOCHAR", but what is often also called Toplit updraft or TLUD char.  
If you make a moderately dense pile of dry (short?), <15%MC)  sticks and light the TOP of the pile, it is easier for the flame to jump to the cellulose in layer two than to consume the charcoal in layer 1, so the pile burns down to the ground.  If you build the pile on wet newspapers, the last layer of charcoal will make enough steam to extinguish the fire.  
While I can't prove it, I presume that the 20% lignin in the wood is the precursor to the charcoal.  
This is the same principle which causes WoodGas Stoves to also produce about 20% charcoal.  
The gas coming from the consumption of the cellulose is probably a reasonable synthesis gas:
C6H10O5 + 1/2 O2 -===> 6CO + 5 H2. (Add two N2 to both sides of this equation if you are using air, instead of O2. ). 
This gas is MUCH richer than the 150 BTU/SCF gas made in the Imbert gasifier, Probably over 250 BTU/SCF, and cleaner because most of the cats and dogs in Imbert gasification come from the Lignin.  
AND, you get a yield of ~20% Higher quality Biochar, since I have measured the temperature in the range 500-600C in TLUD gasifiers. <><><>If the TLUD reaction is carried out in a closed container (eg, 33 gal garbage can) and the gas is cooled, I believe this gas should be ideal for generating power in a Motor Generator set after cooling it, and  passing it through a bucket of the charcoal.  
In that case, a ton of dry wood could produce 400 lb of Biochar PLUS 470 kW of heat or ~ 90 kW of power (assuming 20% conversion efficiency in a motor generator set). 
I'd appreciate Comments, critical or otherwise.  
Tom Reed

Thomas B Reed 280 Hardwick RdBarre, Ma 01005508-353-7841I
Thomas B Reed 280 Hardwick RdBarre, MA 01005508 353 7841
On Dec 23, 2013, at 6:36 PM, "Tom Miles" <tmiles at trmiles.com> wrote:

Ron, I didn’t mean anything quite so personal. :-/ Most of the biochar research has focused on pyrolitic char and not on combustion or gasification char. There is a clear bias toward pyrolysis, or low temperature char. Can anyone really say this is the way that the Amazonians, or anyone else, created the charcoal that we find in the terra preta soils? Or was it smoldering combustion, staged combustion (a la Alex English), or a combination of pyrolysis, gasification and combustion? I know that I have had a lot of bad slash and straw burns that have left a lot more char on the ground than ash. Are there “signatures” in the terra preta char that point specifically to pyrolysis, gasification or combustion?   I see biochar production growing in stages. For the time being a large quantity of char that is sold as Biochar is actually char from gasification. As biochar markets grow we might expect to find more pyrolytic char made “for purpose” but now we have some pyrolitic char and byproducts of gasification (including TLUDs) and combustion.     The “high temperature” gasifier char performs very well and in some applications better than pyrolytic char. Several studies (and some commercial producers) have found that conditioning the char through partially oxidation (to higher temperature) enhances nutrient retention. These products are for improving soil fertility , not necessarily to replace activated carbon. So why not consider CO2 gasification as a possible process step?      One major producer of char in California uses a downdraft gasifier. In a downdraft gasifier wood devolatilizes at or above the oxidation zone. Volatile carbon is oxidized by the air injected from nozzles to make CO2. The hot CO2 reacts with the char to form CO and H2. This occurs in the “reduction zone”. The reduction zone is often shown as a deep bed of carbon but in fact it is usually only a couple of inches thick. Large chips reduce to powdered char in less than 2 inches where gas temperatures are 800-900C. The resultant producer gas is a mixture of this CO from reducing char and the devolatilized gas. Taking CO2 and reacting it with charcoal at 800-900C as Purdue has done is not a lot different so the qualities of the char should be similar.  I think we need to explore all avenues of producing char and energy 1.      Slow pyrolysis – 25%-30% char; 30% oil+gas2.      Fast pyrolysis – 15% char; 60% oil3.      Gasification – 5%-25% char; 75%-95% energy4.      Combustion – 1-5% char; 95% heat Tom       From: biochar at yahoogroups.com [mailto:biochar at yahoogroups.com] On Behalf Of Ronal W. Larson
Sent: Monday, December 23, 2013 2:53 PM
To: Biochar; Tom Miles
Cc: Crispin Pemberton-Pigott; Gasification-Request
Subject: Re: [biochar] Pine char gasification   Tom etal:
    1.   I’m not sure I want to accept the “philia” part of this message  (“philia” goes with “abnormal” and pedophilia at one google site).  I found the word agape - but that sounds presumptuous.  But I do admit to being at the non-sensical end of the char spectrum.  Maybe charphilia is apt.   2.  I know close to zero about any part of gasification, but I can understand why one would promote the idea of recycling the CO2 to get more gas (eventually the Purdue group wants liquid, it seems).  But that has to result in less char - and apparently leaves much higher temperature char.  Eventually it is almost all CO2, for gasification, but I worry that the char produced this (high temperature) way might only be suited to replace AC = activated carbon.   3.  Since Alex English name came up today, we should note that he also recycles CO2.   4.  The dogma of the cult I am in says more char beats more heat, gas or liquid, so I will look forward to some proof that is not correct.   Good luck to the Purdue folk. Ron   On Dec 23, 2013, at 12:58 PM, Tom Miles <tmiles at trmiles.com> wrote:

 Ron, This work is very important for both the biochar and gasification lists. Biochar will be produced at the large, or even small, scale as a co-product of energy (liquid fuels and/or power). The most efficient way to generate power from the gases and vapors from slow pyrolysis (50% of the energy) is probably through charcoal gasification (e.g. run the pyrolysis gases through a charcoal gasifier). There are commercial systems under development to make char and power in this way. There are also commercial systems under development to make liquid fuels through combinations of pyrolysis and gasification. The char products from these and fast pyrolysis processes run from 0% to about 15% of fuel input. I don’t know the fuel or char yield for Cool Planet. This particular study prepared the char with high temperature (826 C) nitrogen.  Wood particles (chips, sawdust) and resultant char particles in this study are larger than for other char studies. Obs

ervations about BET surface area, particle size and the char morphology are very interesting. The char morphology looks different than the SEM images that we typically see. From gasification and pyrolysis we know that pine carbonizes differently than hardwood so it is interesting to see the shredded fibrous appearance of the pine char in this study compared to the neat geometric structures that we often see, which is probably from hardwood chars. The authors observe that the macropore volume is significantly greater than the mesopore or micropore volume of the char. They observe “numerous wide tunnel protruding into the char particles. . . [that] may provide pathways for bulk transport of CO2 into the particle.” Char conversion numbers are interesting. Only 10-12% of the char was gasified at 726 C (BET 391 m3/g) while 98-100% was converted at 896 C. Surface area increased with conversion but not much greater than the 35-47% conversion at 776 C so CO2 gasification could be used to increase surface area at the expense of half of char (660 m3/g). Meso and micro pore volume doubles at the higher rate but stays pretty constant above 776 C. Researchers conclude that a significant proportion of the pore volume is within macro pores although the majority of the internal surface area is within micro pores.  They point out that the mass loss with surface gasification occurs within the smaller pores leading to pore widening. Researchers explain that the char gasification process involves three steps: (1) adsorption of the gas-phase species to the char surface, (2) surface reactions, and (3) desorption of the gasification products from the surface. The latter is the rate limiting process. Recycling CO2 from gasification to gasify the char is an interesting concept that may apply to modifying char properties (e.g. increase surface area) from pyrolysis or recovering energy (heat, power, syngas) in an industrial setting.    There is very little information about gasification or combustion chars. Sometimes it helps to step back from our char-philia (and gaso-phobia) to see what products combined pyrolysis and gasification can produce.   Tom   RL> don’t see any relevance to the biochar list.  (Except if this work shows that char is more valuable in the ground and/or that an approach like Cool Planet’s is more efficient.)  On the biochar list, we should want BOTH high value fuels and charcoal.        This Purdue work is all about gasification of char - not pyrolysis.   I am not sure whether the topic is appropriate for “gasification” either, since that list seems to want gases for engines, not liquids.    __._,_.___Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (5) Recent Activity: ·        New Members 1 Visit Your Group Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • Send us Feedback .__,_._,__________________________________________________
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