[Digestion] Compressing Biogas into a Tank

[Paul Harris]

G'day All,

I agree with Dr A.D. Karve - in fact I have had almost pure methane when
my small digesters were "running down" and gas production was low since
I use a floating drum collector to facilitate gas measurement. I
typically get 70% methane.

Happy Digesting,
HOOROO

David Fulford wrote:
> 
> Gerry, Hi
> 
> Your systems sound typical of those used in places such as India and China.
> Some of the early work in India suggested that the gas production was
> higher at low pressures, so they used counter-balances with a floating drum
> to cause a negative gauge pressure. Unfortunately, if there is a leak in
> the system, air can mix with the gas and cause an explosive mixture. I have
> heard of a floating tank take-off when a farmer tried to demonstrate the
> flammability of the gas by lighting it as it came from the pipe in the top
> of the drum.
> 
> In fact, while the biogas production increases, the methane production does
> not. This is because the solubility of carbon dioxide in water varies with
> pressure, so a reduced pressure causes carbon dioxide to come out of
> solution. An increased pressure actually gives a better quality gas, as the
> carbon dioxide content is reduced. Dr Karve of ARTI claims that his
> floating drum system "pumps" carbon dioxide from the gas, as the pressure
> at the slurry surface in the narrow annulus outside the drum is lower than
> that of the biogas inside the drum, so the dissolved carbon dioxide bubbles
> out around this annulus.
> 
> Cheers,
> 
> David
-- 
Mr. Paul Harris
Room G8, Leske Building
Faculty of Sciences,
The  University of Adelaide, Roseworthy Campus, AUSTRALIA 5371
Ph    : +61 8 8303 7880
Fax   : +61 8 8303 7979
mailto:paul.harris at adelaide.edu.au
I now use "MailGuard" - if you do not get a reply please make contact
again (by fax?)
http://www.adelaide.edu.au/directory/paul.harris
Member IOBB http://www.iobbnet.org/drupal/

CRICOS Provider Number 00123M
----------------------------------------------------------- 
This email message is intended only for the addressee(s) 
and contains information that may be confidential and/or 
copyright.  If you are not the intended recipient please 
notify the sender by reply email and immediately delete 
this email. Use, disclosure or reproduction of this email 
by anyone other than the intended recipient(s) is strictly 
prohibited. No representation is made that this email or 
any attachments are free of viruses. Virus scanning is 
recommended and is the responsibility of the recipient.