My experience installing poly film digesters taught me to keep it as simple as possible to limit the abandonment of the systems afterwards. So in this idea of keeping it simple. What if you evacuated the gas using the exhaust from a car, many of the how to manuals I read when I was carrying out my Biogas project recommended this for inflation of digesters made of poly film. After initial testing I decided not to use it as it adds a step and I didn't see much advantage when I did and didn't use it. But that way you would be mixing a low oxygen gas into the digester to make sure that the Methane was evacuated. I imagine when you stopped getting a flame you would be safe to allow air to enter. But I might be wrong.
On Thu, Oct 28, 2010 at 10:37 AM, Alexander Eaton <[email protected]>wrote: > In a developing world context, it would also make sense to utilize the as > much of the gas production as possible, meaning that maybe a two-chamber > system would make the most sense so that you could allow the HRT to be 100+ > days in each chamber. Then, if there was a flexible portion of each chamber > that could be compressed while venting you would be able to essentially > eliminate any risk of an explosive mixture inside the system. My point it > that it would make sense to push the gas through to the end-use, then open > the chamber while it was empty. Under that scenario I see very little > risk. I may also be talking at a small scale, as I am imagining chamber of > maybe 50 m3 and smaller. Dry digestion for us would be a huge step, as we > have a water limitation that keeps us from installing digesters in many > areas of Mexico and Latin America. > > I am returning from the UN Genus waste to energy meeting in Costa Rica, > where I did have a really interesting discussion about a multi-chambered dry > digester system for food waste and solid waste collected at a larger level > and installed at landfills. In that scenario, I also envision some sort of > flexible cover that could be vacuum pumped empty before the cover was > opened. We were also talking about cells with 2+ year HRTs. > > Does anyone have some good info on dry digestion, appropriate substrates, > HRTs and gas production rates? > > A > > On Thu, Oct 28, 2010 at 10:22 AM, David <[email protected]> wrote: > >> >> Yvonne, >> >> On 10/28/2010 1:53 AM, Voegeli, Yvonne wrote: >> >> After visiting a Bekon biogas plant in Switzerland, I’m especially >> concerned regarding the opening of the digester for emptying and refilling. >> Before opening the door, the digester has to be vented in order to avoid a >> gas-air-mixture which is explosive. This installation seems to me rather >> complicated.... >> >> ...Is it possible to install a simpler venting system? >> >> >> I would venture a guess that where the inlet air is being forced in by >> bubbling through water, and the outlet air likewise is allowed to escape by >> bubbling through water, then the only place in the system where there would >> be both a potentially explosive gas mixture and the potential of a spark >> would be at the evacuation point of the exiting gas mixture. Where >> sufficient air is blown over the water through which the evacuating air is >> exiting, then the risk of any explosion would, I would think, be very close >> to zero. >> >> >> >> d. >> -- >> David William House >> "The Complete Biogas Handbook" www.completebiogas.com >> *Vahid Biogas*, an alternative energy consultancy www.vahidbiogas.com >> >> "Make no search for water. But find thirst, >> And water from the very ground will burst." >> (Rumi, a Persian mystic poet, quoted in *Delight of Hearts*, p. 77) >> >> http://bahai.us/ >> >> _______________________________________________ >> Digestion mailing list >> >> to Send a Message to the list, use the email address >> [email protected] >> >> to UNSUBSCRIBE or Change your List Settings use the web page >> >> http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org >> >> 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/ >> >> >> > > > -- > Alexander Eaton > Sistema Biobolsa > IRRI-Mexico > > Mex cel: (55) 11522786 > US cel: 970 275 4505 > > [email protected] > [email protected] > sistemabiobolsa.com > www.irrimexico.org > > _______________________________________________ > Digestion mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org > > 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/ > > > -- Joshua D Bogart Program Coordinator Trees for the Future Siguatapaque HN Barrio Macaruya, Calle, 21 de Agosto cellular (504) 9696-3700 home/casa 740-1060
_______________________________________________ Digestion mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org 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/
