[Digestion] Photosythetically Conditioned Biogas Compression

Wed Oct 30 03:07:00 CDT 2013

Paul and listers, Hello,

People have expressed safety concerns over the underground concrete 
designs used in China, India, Nepal and elsewhere in Asia. An explosion 
in an underground chamber would throw slurry out of the reservoir, or, 
at the worst, cause the dome to crack, throwing soil around.

I know which I would prefer: with the choice of being covered in slurry 
(if I was standing in the wrong place) or being in range of shrapnel 
from a metal tank.

Best wishes,
David
davidf at kingdombio.com

******************************************************
Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5 4PU
        Tel: +44(0)118 326 9779 Mob: +44(0)7746 806401
Kingdom Bioenergy Ltd, www.kingdombio.com, davidf at kindombio.com
                                 Skype Identity: djfulford

------ Original Message ------
From: "Paul Harris" <paul.harris at adelaide.edu.au>
To: digestion at lists.bioenergylists.org
Sent: 30/10/2013 00:43:33
Subject: Re: [Digestion] Photosythetically Conditioned Biogas 
Compression
>G'day All,
>
>Variable Volume (VV) storage has a number of advantages over 
>Compression (C), which at 20 psi will not give you much advantage 
>anyway. VV can be plastic, avoiding the shrapnel problem, and saves the 
>cost/complication/energy consumption of C. You also get a simple visual 
>indication of gas production/use with VV. Several members of this list 
>can probably verify that with a plastic storage you get a hole and a 
>rapid flare of gas rather than a large explosion
>
>When we were talking about storing biogas at our University research 
>site the maintenance supervisor said we would have to use steel 
>containers and I thought to myself that I would rather stand alongside 
>a plastic VV storage during a fire than be anywhere near a steel 
>cylinder.
>
>Happy Digesting
>HOOROO Mr Paul Harris Visitor to The University of AdelaideOn 
>30/10/2013 8:00 AM, David wrote:
>>
>>
>>Jacob,
>>
>>Take 2,
>>
>>
>>On 10/29/2013 11:08 AM, Jacob Douenias wrote:
>>>Hi all!
>>>
>>>Excited to join this group. I am a researcher working at carnegie 
>>>mellon university in pittsburgh.I am working on a startup where we 
>>>are making biogas at home and biologically purifying this gas.
>>>
>>>Our gas composition at the end of our system is comprised of about 
>>>80% methane and 20% oxygen. We are concerned about the storage and 
>>>possible compression of this gas due to the presence of oxygen in the 
>>>gas. I know that 80% methane is well above the upper explosive limit 
>>>of methane (our working conditions are 15-20psi for final gas 
>>>compression and 60-80 degrees farenheight). I know it is bad practice 
>>>to have oxygen mixed with combustible gas but at our composition 
>>>should we worry about safely compressing this mixture to a low 
>>>pressure (15-20psi) and storing it in gas cylinder? I would really 
>>>love to hear what you think as I am just an architect who happens to 
>>>read a lot about biochem.
>>
>>
>>The upper limit of flammability for methane in air is of course about 
>>15%. I took a bit of time between tasks to look it up, and in pure 
>>oxygen, the upper limit is 61%. (The lower limit is about the same in 
>>either case: ~5%.) There is a formula proposed by Zabetakis which 
>>indicates-- if I've done my figgers correct-- that at 20 PSI it should 
>>increase to perhaps 63% methane in oxygen. But note: that is an 
>>extrapolation, not a test result. And I would not call 80% "well 
>>above" that extrapolated limit.
>>
>>I have to say, that particularly if I had children in the house-- you 
>>did say "biogas at home", and you did say "we"-- I would not want to 
>>take any implied risks. In the case of the information I have just 
>>given you, for example, maybe it's true, maybe I made a mistake. Maybe 
>>you didn't measure the gas ratio correctly and maybe it will change, 
>>if the presumed algae get frisky. Maybe, maybe.
>>
>>If it were me, I would have a tendency to look at the gas cylinder and 
>>wonder whether I was unintentionally planning on making a bomb with 
>>its own built-in shrapnel, and then I would begin to wonder how I 
>>might store the gas some other way, such that if the marginally 
>>unthinkable did happen, nobody would be likely to be nearby, and 
>>nothing sharp and glittering would be hurled hither and thither as a 
>>result.
>>
>>
>>
>>
>>
>>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/
>>
>>
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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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