[Digestion] Photosythetically Conditioned Biogas Compression

[Paul Harris]

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 Adelaide

On 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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