David, You do have two atmospheres of ABSOLUTE pressure at the bottom of a 33 ft column of water however you only have one atmosphere of relative pressure (difference between top of the tank and bottom of the tank) under 33 ft of water.
Art Krenzel, P.E. PHOENIX TECHNOLOGIES 10505 NE 285th Street Battle Ground, WA 98604 360-666-1883 voice [email protected] Date: Fri, 19 Nov 2010 14:31:12 -0800 From: [email protected] To: [email protected] Subject: [Digestion] Pressure Dear friends, Excellent discussion lately. I was particularly impressed by the article by Dr. Fulford about biogas burners. Best information I've seen on this subject. I wanted to ask two questions just now, and I'll therefore be sending another message to the list quite soon. Separating the questions will allow the development of two different threads, if there is much discussion about either question. The first question concerns pressure. Obviously AD is able to generate biogas at pressure. Any vessel 33 feet deep will have two atmospheres of pressure at the bottom, and there are a number of digesters which are at least that deep. The gas produced in deeper vessels-- if they are not stirred-- tends to have a bit less carbon dioxide, because that gas dissolves rather easily as compared with methane. But I am not familiar with any work that has been done regarding the relationship between pressure and the rate of production. That is, one would expect that at increasing pressure, less biogas (measured, of course, at STP) would be produced. But what is the relationship? How dramatic is the reduction in the rate of production with deeper vessels? 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/
_______________________________________________ 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/
