[Gasification] [biochar] Gasification, TLUDs and Biochar

[Stephen Joseph]

Hi Tom

I think you need to be very careful about stating temperatures for maximum adsorption.  For example Uchima et al found adsorption of heavy metals was highest at temperatures of 350C for a high mineral ash biochar.  Ammonia uptake is also highest at this temperature.  Other gases solids and liquids have maximum adsorbtivity at different temperatures and are also a function of feedstock.  I am working on adsorption of heavy metals on wheat straw biochar in China.  We see at least three mechanisms, one related to mineral matter, one related to function group composition and concentration and one related to pH and surface area.

There is a general misunderstanding about temperature and properties.

Regards
Stephen Joseph
On 15/05/2013, at 2:03 PM, Tom Miles wrote:

> This should be of interest to biochar and gasification enthusiasts.
> 
> Thanks Tom Reed. 
> 
> Tom Miles
> 
> -----Original Message-----
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
> Thomas Reed
> Sent: Tuesday, May 14, 2013 8:55 PM
> To: stoves at lists.bioenergylists.org
> 
> Dear Gasologist
> 
> We should all distinguish clearly when discussing gasification between 
> 
> O Total gasification (eg an Imbert gasifier) that converts typically 98% ot
> the wood to WoodGas
> 
> O Pyrolytic Gasification (TLUD and larger) which primarily gasifies the
> cellulose and pyrolyses the lignin to ~20% charcoal
> 
> <><><>
> 
> The smoke from a TLUD stove will leave a deposit on a cold steel plate. I
> was interested in finding out how much "tar" was in the TLUD combustible gas
> before it is burned. 
> 
> I measured the "tar" production from a TLUD stove by putting a 4" galvanized
> elbow (wrapped in wetted towels) in the stove, and a 4 ft length of
> galvanized pipe followed by another elbow and chimney.
> 
> Instead of the tarry deposit I expected, I obtained about 1% of a brown
> powdery deposit that was quite dry to the touch. 
> 
> I now wish I had saved it and analyzed it further. But I suspect a similar
> experiment on the Imbert gas would give a much higher "Tar" content,
> originating mostly from the lignin. 
> 
> <><><>
> 
> The charcoal resulting from the TLUD is generally a bonus, depending whether
> you have a use for it. The temperature of the flaming pyrolysis below the
> surface of the TLUD stove is between 500 and 700 C (measured with a Cr-Al
> thermocouple). For this reason, the charcoal produced is much more
> absorptive than commercial (<450 C) charcoal. 
> 
> This spring I am doing some planting tests on TLUD charcoal vs commercial
> charcoal. I'll report results. 
> 
> Onward to the future of charcoal...
> 
> Tom Reed
> 
> Dr. Thomas B Reed 
> Tombreed2010 at gmail.com
> 508-353-7841
> 
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