[Gasification] [biochar] ICM gasifier project comes to a close
tombreed2010 at gmail.com
Sun Apr 14 08:54:40 MDT 2013
Dear Peter and Kerry and all:
The following discussion is concerned with two categories of charcoal:
O straight pyrolysis charcoal, made presumably at 400-450C using the exothermic rise from 300-400-350C to reach final temperature
O gasifier charcoal, left over from gasification which can exceed 1000C
I'd like to stress a third category.
"Autopyrolytic Charcoal", such as is produced in the WoodGas stove. I have measured the temperature of formation of the charcoal as 500-700 C, depending on how much air is inducted or blown in, but the measurement may have been biased by the flame. In any case, this is the charcoal produced in WoodGas stoves or PyroPiles of wood by burning off the volatile cellulose gas during which the lignin becomes the harder to burn charcoal.
I'd appreciate positive and negative comments on this third category which is mostly what I make now that Spring is just around the corner here in Barre, Mass.
Thomas B Reed
280 Hardwick Rd
Barre, MA 01005
508 353 7841
On Dec 27, 2012, at 7:17 PM, Peter & Kerry Davies <realpowersystems at gmail.com> wrote:
> Thanks Tom,
> Yes I agree that more gasifier chars are being used than most people realise, the growing use of TLUD stoves can only accelerate this, and may yet be one of the important legacy's of the good people (many on this list) who have developed and promoted them.
> Unfortunately amongst the research community in Australia a peculiar and unwritten bias developed where only pyrolysis chars seem to be accepted in testing trials, I suspect in part because it is easy to make and study such chars in a lab.
> The alkalinity statement came from our experience working with Bluescope Steel on metallurgical chars, their testing showed our gasifier chars from both softwood & hardwood chips (pine and eucalyptus) to have a lower alkalinity compared to pyrolysis chars from oil mallee residues which were quite alkaline (fixed carbon <60%), so much so that the latter could not be used alone as a reductant but had to be blended with other carbon sources.
> We have since put oil malley leaf and stems through our system and came up with fixed carbon numbers >80% similar to our original trial results with wood chips above, though the ash analysis would be different.
> Perhaps interestingly we have noted our livestock greatly prefer gasifier chars to chew on when given two sources to choose from, and much preferred hardwood char to softwood, results mirrored in the Bluescope testing on steel making suitability, they all make steel better than coke, but hardwood gasifier chars were exceptional.
> However the Bluescope work example is the only one I have PH data for, more generally you may be right and my assumptions may not hold true either for other types of gasifiers or feed stocks. This is one the reasons we have been trying to get gasifier chars accepted over here in the biochar research, to get proper independently documented comparative information.
> I was told by one research source that gasifer chars would be inferior for agronomic use compared to pyrolysis chars because of the different crystalline structure between them, however they were unable to point me to any work on this, published or unpublished, that supported this conclusion. Whereas work by Greening Australia over here using our chars showed them to have equal or superior outcomes to baseline control and pyrolysis char plots.
> On 28/12/2012 7:00 AM, gasification-request at lists.bioenergylists.org wrote:
>> There are probably more gasifier chars used as biochar than most people
>> realize. I agree that gasification chars seem to be very useful for use as
>> biochar. I haven't really seen enough thorough analysis of gasifier chars to
>> be able to generalize on their characteristics as distinct from pyrolysis
>> chars. I do question your statement about gasifier chars being less
>> alkaline than pyrolysis chars. Given the same feedstock a gasifier char will
>> have higher ash, higher pH, and likely higher alkalinity than a pyrolysis
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