[Stoves] response to Dr. A.D. Karve

[adkarve]

Dear Stovers,
I wish to express my regrets about the wrong concept that I had about Prof.
Antal's process.  I should have contacted him to get more information. I was
only reporting what a chemical technologist colleague told me, which is
however valid for the processes he was refering to, namely natural coal
formation and conversion of wet biomass into charcoal by heating it in a
pressure
vessel.
However, I wish to point out that Prof. Antal has conceded that the charcoal
produced by him has typically less than 25% volatile matter.  Assuming that
his process yields charcoal containing, on an average, 20% volatile matter,
it explains the high charcoal yield. If a fifth of the weight is deducted
from his 40% char yield, one gets a figure of 32% pure carbon. The
oven-and -retort process yields about 33% char. It is free from volatiles
and comparable to high quality coke. Industries using coke are willing to
use our charcoal as a substitute for coke.
Yours
A.D.Karve

----- Original Message -----
From: Michael J Antal <mantal at hawaii.edu>
To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
Cc: Priyadarshini Karve <priyadarshini.karve at gmail.com>
Sent: Sunday, June 10, 2007 3:20 AM
Subject: [Stoves] response to Dr. A.D. Karve


> Dear friends: as most of you know, our research results concerning the
efficient production of charcoal have been recorded in dozens of archival
journal publications over the past 30 years.  These archival journals are
available in most university libraries around the world.  On numerous
occasions I have offered to send these publications to anyone who requests
them.  It's a pity that Dr. A.D. Karve never took the trouble to request
them from me.
>
> The conditions employed by Dr. Karve's chemical technologist have nothing
to do with the conditions that we employ.  Dr. Karve can discover this for
himself by reading our papers.
>
> In our more recent work (during the past 6 years) we have reported our
yields as fixed-carbon yields that reflect only the yield of fixed-carbon in
the charcoal.  These yields have reached the thermochemical equilibrium
limit.  These charcoals always have low (typically less than 25%, often less
than 10%) VM.  All of our engineering papers always report the proximate
analyses of our charcoals, including its VM content.
>
> I will be glad to send Dr. Karve copies of our archival journal
publications.  He only needs to request them.
>
> Best regards, Michael.
>
> ----- Original Message -----
> From: adkarve <adkarve at pn2.vsnl.net.in>
> Date: Friday, June 8, 2007 11:08 pm
> Subject: [Stoves] 40% yield of charcoal
> To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
> Cc: Priyadarshini Karve <priyadarshini.karve at gmail.com>
>
> > Dear Stovers,
> > For the last couple of years we have been reading in this forum
> > about a
> > charcoal making process that yielded almost 40% char. This process was
> > developed in Hawaii. All that was revealed about this process was
> > that it
> > was conducted under pressure.
> > A chemical technologist in Pune (India), with whom we are
> > collaborating in
> > another project, demystified this particular charcoal making process.
> > According to him, the Hawaiian process mimicked the formation of
> > mineralcoal in nature, where biomass got heated while buried under
> > tons of soil and
> > rock. One can imitate this process in a laboratory by filling wet
> > biomass in
> > a pressure vessel and heating it to 200 degrees celsius.  The
> > water in the
> > biomass gets converted into steam, which exerts pressure on the
> > biomass. The
> > volatiles that normally escape from the biomass in the process of
> > pyrolysis,are not allowed to escape because the biomass is under
> > pressure. As a
> > result, the tar is retained in the charcoal, adding to the weight
> > of the
> > charcoal. That is the secret of the 40% charcoal yield. This
> > charcoal is
> > however of a poor quality, because when one ignites it in a stove, the
> > volatiles escape from it, giving rise to smoke and soot. Autoclaving
> > distillery effluents with high organic content at 200 degrees C, under
> > pressure, is already being practised in some distilleries in
> > India, as a
> > measure of pollution control.
> > Yours
> > A.D.Karve
> >
> >
> >
> > _______________________________________________
> > Stoves mailing list
> > Stoves at listserv.repp.org
> > http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
> > http://stoves.bioenergylists.org
> > http://info.bioenergylists.org
> >
>
> _______________________________________________
> Stoves mailing list
> Stoves at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
> http://stoves.bioenergylists.org
> http://info.bioenergylists.org