[Stoves] Characteristics of biochar was Re: [biochar] grassifier & cedar chip char

Alex English english at kingston.net
Tue Feb 5 17:36:28 CST 2013


Perhaps it should be called fixed-up carbon, its whats left after 
getting rid of the rif-raf that can['t tough it out in the kitchen when 
thing get hot.

What other tests are there that would give a better representation of 
the biological recalcitrance of char?

Alex

On 05/02/2013 5:33 PM, Frank Shields wrote:
>
> Paul,
>
> My biggest problem with the term 'fixed carbon' is that it is not a 
> measurement of the carbon at all. Just the stuff left over after 
> heating that can contain Oxygen and hydrogen.
>
> Frank
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On 
> Behalf Of *Paul Anderson
> *Sent:* Tuesday, February 05, 2013 1:17 PM
> *To:* Crispin Pemberton-Pigott; Discussion of biomass cooking stoves; 
> biochar at yahoogroups.com; Hugh McLaughlin; Ron Larson; Thomas Reed
> *Subject:* Re: [Stoves] Characteristics of biochar was Re: [biochar] 
> grassifier & cedar chip char
>
> Crispin,
>
> The influence of the coal industry on the testing is not a perfect 
> match for what biomass gasification is all about and the testing of 
> biomass and biochar.
>
> Biomass can be 50% carbon, but with decay it will all go to CO2.      
> Fixed carbon must be created in the carbonization process.
>
> In Atlanta airport about to fly to Uganda for 3 weeks.   I hope that 
> others will comment, and not rely on me to reply.
>
> Paul
>
>
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:psanders at ilstu.edu  <mailto:psanders at ilstu.edu>    Skype: paultlud  Phone: +1-309-452-7072
> Website:www.drtlud.com  <http://www.drtlud.com>
>
> On 2/5/2013 10:09 AM, Crispin Pemberton-Pigott wrote:
>
>     Dear Paul
>
>     1.As far as I know, there is no "fixed carbon" in the biomass.  
>     It is fixed during the process of carbonization/pyrolysis.
>
>
>     That is the problem -- it you give a sample of wood to a lab and
>     they perform a 'coal analysis test' on it you will get a report on
>     the amount of 'fixed carbon'. The point I was making is that it is
>     a metric of convenience arising from the test procedure, not a
>     reference to a material property.
>
>
>     2.  Some biomass such as seeds have "oils" that vaporize or are
>     volatile.   They are generally not pyrolyzed. However, the lignin
>     and other "stuff" in biomass is what is pyrolyzed and gives off
>     pyrolytic gases that are volatile.   At low temperatures, the
>     future volatiles are not yet in a form that can be called
>     volatile.   But they will volatize when subjected to higher
>     temperatures.
>
>     I will accept what the chemist eventually clarify for us.
>
>     The % Volatiles are defined as that fraction that will boil
>     (literally) at a given temperature. Choose you temperature. So
>     when using a defined method, the result changes with the
>     temperature your use.
>
>     See for example http://www.sigmatest.org/Coal-Testing-India.html
>
>     "*Proximate analysis - Moisture, Volatile matter, Ash and Fixed
>     Carbon: *
>
>     "Proximate analysis indicates the percentage by weight of the
>     Fixed Carbon, Volatiles, Ash, and Moisture Content in coal. The
>     amounts of fixed carbon and volatile combustible matter directly
>     contribute to the heating value of coal. Fixed carbon acts as a
>     main heat generator during burning. High volatile matter content
>     indicates easy ignition of fuel. The ash content is important in
>     the design of the furnace grate, combustion volume, pollution
>     control equipment and ash handling systems of a furnace."
>
>     This week we tried to get some tests of fuel content and were
>     offered 'coal analysis' tests. It all sounds good but if you look
>     into the procedure, you are not getting what you think -- i.e. it
>     is not an analysis of the elements that we are used to talking
>     about in the biomass fuel biz.
>
>     Getting a lab test result of this type using an instrument
>     designed to do ANSI/ASTM D3172 tests
>     http://www.marsap.com/anamedinstru.com/coal.shtml  and turning it
>     into a 'standard' analysis is quite messy and I have a spreadsheet
>     for doing that if you need it. It was necessary for the Asian Dev
>     Bank (which built the SEET Lab) to do this because all that is
>     available is standard coal analyses, but the HTP test method is
>     more scientific in the sense that it uses the chemical composition
>     of the fuel, not an approximation of it.  It is also necessary to
>     get the 'as received, ash-free' heat content. Coal analysis
>     methods gives AR (as received moisture), AD (after drying but not
>     'actually dry') and FC (fixed carbon, but not 'actual carbon'
>     content). It also view some of the moisture as 'inherent'.
>
>     There are two things which come back 'wrong': the moisture content
>     and the carbon content. Finding out what the carbon content of the
>     volatiles was is nearly impossible. The right approach is XRD and XRF.
>
>     To give you an idea of how far wrong the method is for determining
>     Carbon, here is a standard test result of some coals and sawdust
>     briquette. It is well known that the sawdust contains about 50%
>     Carbon. It was rated as having 16% 'fixed carbon'. In other words
>     it is basically a useless measurement when it comes to biochar (or
>     anything else).
>
>     Regards
>
>     Crispin
>
>
>
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