[Digestion] Digestion Digest, Vol 14, Issue 14

Paul Harris paul.harris at adelaide.edu.au
Tue Oct 18 18:23:39 CDT 2011


G'day All,

In response to Bill here are the two posts from AD Karve (on the
Gasification List - under the thread "reducing temp. Of gasification").

Tues Oct 4

Dear Henry,
 There are a lot of very simple ideas that need to be tested.  I am
currently working on increasing the efficiency of biogas digesters and
feel that it might be possible to reduce the size and the capital
expense of a biogas system. For instance, when I filled the digester
with charcoal, my system accepted three times the normal daily input
and produced three times as much gas.
How much electrical energy would be required by the electric arc to
produce producer gas? One can perhaps achieve the same temperature
with paraboloid mirrors and sunlight.
Yours
A.D.Karve


Wed Oct 5
Dear Wishwanathan,
we are still working on the idea. It works. We have been able to
reduce the size of the digester to 1/3. Charcoal has to be enclosed in
a net bag. It does float in the initial stages, but later it absorbs
water and becomes heavy and sinks.
Yours
A.D.Karve

Happy digesting,
HOOROO

Mr. Paul Harris, Room 202 Charles Hawker Building, Faculty of Sciences, The 
University of Adelaide, 
Waite Campus, PMB 1, Glen Osmond SA 5064 Ph  : +61 8 8303 7880      Fax  :
+61 8 8303 4386
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-----Original Message-----
From: digestion-bounces at lists.bioenergylists.org
[mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Bill Rucks
Sent: Wednesday, 19 October 2011 5:56 AM
To: digestion at lists.bioenergylists.org
Subject: Re: [Digestion] Digestion Digest, Vol 14, Issue 14

Greetings 
Could I get the thread relating to Dr Karve biochar and biogas - 
It seems to bridge between 2 list !! Gasification and Digestion 
I have looked back through previous issues and vol - but cannot see the
original post !!

Bill Rucks 


 

-----Original Message-----
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Sent: Wednesday, 19 October 2011 8:00 a.m.
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Subject: Digestion Digest, Vol 14, Issue 14

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Today's Topics:

   1. Re: [Stoves] Karve connecting Biochar and Biogas (Duncan Martin)


----------------------------------------------------------------------

Message: 1
Date: Tue, 18 Oct 2011 07:04:50 +0100
From: Duncan Martin <duncanjmartin at gmail.com>
To: For Discussion of Anaerobic Digestion
	<digestion at lists.bioenergylists.org>
Subject: Re: [Digestion] [Stoves] Karve connecting Biochar and Biogas
Message-ID:
	<CAHiLkckDfQ0xCWq5irLWK4+boYgOH3RpwE6DQ9-HRzeZ6BthGQ at mail.gmail.com>
Content-Type: text/plain; charset="windows-1252"

Dr Karve's clarification of his original point is helpful - but I think it
still leaves some questions.

He implies that the stimulatory effect of charcoal is long-term and gradual,
so the mechanism isn't likely to be the absorption of a nutrient excess or
ant other inhibitors.

However, in this context, I'm not convinced by a role as a biomass support:

   1. Would the flow velocities in a digester be high enough to strip
   biomass off such a support medium? If not, it's hard to see a significant
   role as a source of inoculum. (Bear in mind that anaerobic filters are
   designed to retain biomass at much higher velocities.)
   2. The increased feed rate was 3kg (dry wt) per day, which implies about
   30L of food waste per day by volume (neglecting for the moment the free
   water in which it is suspended). In a 1000L digester, that implies a mean
   retention time of 33 days. (And a very long retention time of 100
days *before
   *adding the charcoal.) That implies a large volume of partly-digested
   solids for colonization by microbial flora. This would provide a major
   source of inoculum, so it's not obvious that charcoal would add
   significantly to it. (Yes, native charcoal has a massive surface area per
   unit weight - but that advantage would disappear if it was covered in
   biofilm.)
   3. In practice, the feedstock would probably be more dilute (depending on
   the digestion technology in use), so the retention time* would be
reduced.
   However, it seems unlikely that the volumetric throughput would be high
   enough to negate the above arguments. (*It would be interesting to know
what
   it was...)

Yes, Dr Karve's experiment allowed an increased feed rate and, as Crispin
says, the higher gas yield is a direct result of the larger volume of
"material ingested". However, that doesn't explain *how *the increased feed
rate became possible.

I would conclude that Dr Karve's observation remains unexplained - we
shouldn't jump to conclusions.

Duncan Martin PhD
Cloughjordan
Ireland


On 11 October 2011 17:21, Crispin Pemberton-Pigott
<crispinpigott at gmail.com>wrote:

> Dear Ron?N?All****
>
> ** **
>
> I think everyone involved in the gas business is clear that the production
> increase is the predictable results of a change in fuel (not grasses/dung)
> to high starch/sugar feedstocks.****
>
> ** **
>
> The increase in gas is not apparently the result of the char which is used
> more as a culture or host medium to ensure inoculation of the incoming
> feedstock. The speed of gas production is the result of the material
> ingested.****
>
> ** **
>
> Dr AD has been in communication with David House (author of the most
> important handbook on the subject) and everyone seems agreed on the
basics.
> The producing increase by this means was demonstrated as long ago as the
> 1920?s.****
>
> ** **
>
> Regards****
>
> Crispin****
>
> ** **
>
> ** **
>
> *From:* stoves-bounces at lists.bioenergylists.org [mailto:
> stoves-bounces at lists.bioenergylists.org] *On Behalf Of *
> rongretlarson at comcast.net
> *Sent:* October-05-11 11:05 PM
>
> *To:* Anand Karve; gasification at lists.bioenergylists.org; Discussion of
> biomass; biochar; digestion
> *Subject:* [Stoves] Karve connecting Biochar and Biogas****
>
> ** **
>
> AD (cc four lists):
>
>     I have not previously seen the connection between Biochar and Biogas
> that you described (below) today on the gasification list.     In
> particular, you say you "..* filled the digester**
> with charcoal, my system accepted three times the normal daily input
> and produced three times as much gas.*"
> I think what you describe can be a very powerful push for both Biochar and
> Biogas.  Can you describe what you have learned a little more?
>
>      I know too little of digesters, so this is not clear.  I think I know
> your kitchen-sized inverted "barrel" gas chamber and think I understand
the
> last part - of getting three times as much gas in the next 24 hours or
less
> (and 3X is a huge change!).   Does the idea of accepting three times more
> mean essentially the same thing?  I would think you could "jam" any amount
> in;  what limits acceptance?
>
>     Do you agree that this is very important new information?  Do you
agree
> this information could help speed up both technologies?  I believe there
is
> wide agreement that Biochar benefits from added biological material (that
> would not be long-lived from a sequestration perspective).  Is there any
> reason to think that the traditional use of digester effluent for ag
> improvements will be in any way harmed if it is continued through the
> addition of carbon-negative Biochar?  Should this not promote sales of
your
> charcoal-making stoves?
>
>    If I haven't asked quite the right question - please answer the right
> one.  And congratulations on learning and reporting this.
>
> Ron
>
>
>
>
>
> The remainder from AD Karve today on the gasification list:
>
>  There are a lot of very simple ideas that need to be tested.  I am
> currently working on increasing the efficiency of biogas digesters and
> feel that it might be possible to reduce the size and the capital
> expense of a biogas system. For instance, when I filled the digester
> with charcoal, my system accepted three times the normal daily input
> and produced three times as much gas.
>    < snip>
> Yours
> A.D.Karve
> ***********************************************
>
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>
> for more information about digestion, see
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>
>
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End of Digestion Digest, Vol 14, Issue 14
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