[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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