[Stoves] Comments about T-LUDs: Types of carbon

[Kevin Chisholm]

Dear Frank
----- Original Message ----- 
From: <frank at compostlab.com>
To: "Kevin Chisholm" <kchisholm at ca.inter.net>; <psanders at ilstu.edu>
Cc: <stoves at listserv.repp.org>
Sent: Sunday, October 08, 2006 11:35 PM
Subject: Re: [Stoves] Comments about T-LUDs: Types of carbon


> Kevin,
> Some great info.

I'm glad you found it helpful.

> I often wonder what effect nitrogen has on fuel. Plants can have around 5% 
> N
> or 30+ % protein. Do you have info on that?

I don't, and I haven't seen information on the combustion of protein. Your 
suggestion for fuel testing could be quite helpful in this regard.

Best wishes,

Kevin
>
> Thanks
> Frank
>
>
>
>
>
> On Sun, 8 Oct 2006 22:29:26 -0300, Kevin Chisholm wrote
>> Dear Paul
>>
>> Ash can be inert, but it could also be very influential on the
>> operation of a biomass gasification or combustion system.
>>
>> Consider Silica, or SiO2, as a simple case. It has a melting point,
>>  as a pure compound, of about 3,200 degrees F. As pure silica, it is
>> inert to the combustion process. Quicklime, or CaO, has a melting
>> point of about 4,000 degrees F, and as a pure compound, it also is
>> inert to the combustion process. HOWEVER, when mixed together, in an
>> equimolar ratio, the melting point drops to about 2,100 degrees. Add
>> the right amount of Al2O3, FeO, and K2O, and you can end up with a
>> slaggy mess with a melting point in the 1,300 to 1,500 degree F range.
>>
>> K2O has a catalytic effect that promotes the reaction of S with CaO;
>> I don't know, but if it can exert a catalytic effect on one reaction,
>>  it just might catalyze others.
>>
>> There is also the phenomenon of "alkali pumping"... when K2O reaches
>> the lower and hotter zones of an updraft gasifier, it is reduced to
>> metallic Potassium, which is then carried upward to the cooler fuel
>> bed, where it "back reacts" with CO2 to again form K2O. This imposes
>> a significant endothermic heat load on the reaction zone.. If it
>> recycles sufficiently, it can interfere with gas passage through the
>> bed, and cause channeling.
>>
>> Lime in wood would normally be as a carbonate or silicate, or
>> perhaps even an organo-metallic compound. It would not be found as
>> CaO per se. When the char is burned, if the Ca was there as a
>> Calcium Carbonate, CaCO3, it could have a significant effect on the
>> combustion process. CaCO3 requires in the order of about 4,000 BTU
>> per pound of Calcium Carbonate that is converted to quicklime, CaO.
>> If there was a significant presence of CaCO3 in the char, it could
>> impose a very significant endothermic heat load on the reaction zone.
>>
>> A very simple test will tell if CaO, Na2O, and K2O are present in
>> the ash... simply cool the ash in a sealed tin can, and when at room
>> temperature, add water. If there is significant quantities of these
>> components present, they will hydrate, with the liberation of
>> noticeable heat.
>>
>> Best wishes,
>>
>> Kevin
>> ----- Original Message ----- 
>> From: <psanders at ilstu.edu>
>> To: <frank at compostlab.com>
>> Cc: <stoves at listserv.repp.org>
>> Sent: Sunday, October 08, 2006 12:44 PM
>> Subject: [Stoves] Comments about T-LUDs: Types of carbon
>>
>> > Frank and all,
>> >
>> > Your comments about carbon arise questions to me.
>> >
>> > Quoting frank at compostlab.com:
>> >> As I see it there are two types of carbons left in the ash. One
>> >> carbon that is
>> >> left from the unburned wood and the other carbonates.
>> >      [and]
>> >> Ash, even in wood, is much more than just unburned organic material.
>> >
>> > I could easily be wrong, but to me ash is the absolutely inert,
>> > non-combustible
>> > residuals from combustion, and does NOT contain unburned organic
>> > material. Silica and clinkers etc are all part of the inert "ash."
>> > Maybe my terms are
>> > incorrect.
>> >
>> > Is a "carbonate" inert, meaning, are the carbon atoms LOCKED into
>> > carbonates? If so, then carbon-in-carbonate is
>> > carbon-not-available-for-combustion.
>> >
>> > Hydrocarbons are the backbone of combustion.  And there is
>> > carbon-in-unattached-form. (Is that pure carbon, or fixed carbon or
>> > elemental
>> > carbon, or all of those names?)    The unattached carbon also has great
>> > fuel
>> > value.
>> >
>> > I know that good-quality char (quite pure carbon) can be pulverized and
>> > added to
>> > soil as a great soil builder.  But is that true for "carbonates" also?
>> >
>> > Yes, this relates to T-LUDs because those devices deal with the various
>> > forms of
>> > carbon compounds and element at distinct times in the T-LUD pyrolytic
>> > gasification.
>> >
>> > Paul
>> >
>> >
>> > ----------------------------------------------------------------
>> > This message was sent using Illinois State University Webmail.
>> >
>> >
>> >
>> > _______________________________________________
>> > Stoves mailing list
>> > Stoves at listserv.repp.org
>> > http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
>
>
> --
>