[Digestion] Dry fermentation in developing countries

Markus Schlattmann firmen at schlattmann.de
Thu Oct 28 15:03:46 PDT 2010


Hi,

>>> I would venture a guess that where the inlet air is being forced in 
>>> [to the batch container] 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.
>>> The process I attempted to describe should be easy to implement 
>>> whether in a situation where low cost is a primary consideration, or 
>>> in a shiny packaged version for a high tech system. What have I 
>>> missed here?
>

I don't know if I have understood this 100% correctly, but if you have 
inlet air you will get a potentially explosive atmosphere inside the 
digester. You will reach this at some point (when too low oxygen reaches 
ignitable concentration). And the time this explosive atmosphere lasts 
inside the digester depends on how fast you can blow the air (until 
methane is diluted too much). So you will get a potentially explosive 
atmosphere anyway, perhaps even longer in contrast to open the door at 
once? (So methane is diluted fast?). I don't know...In both cases one 
should take care of what technical equipment is used in areas with 
potentially explosive mixtures (the requirements given by law also may 
vary between countries).

I'm not a safety expert, but I just want to make list readers aware that 
flammable atmospheres may lead to severe personal and material damage.
E.g. have a look at this (this has nothingto do with dry fermentation, 
but just shows what can happen if there's a flammable atmosphere and an 
ignition source):

http://feuerwehr-biberach.de/index.php?id=45&tx_ttnews%5Btt_news%5D=148&tx_ttnews%5Bbackpid%5D=1&chash=c92cb6605c 
<http://feuerwehr-biberach.de/index.php?id=45&tx_ttnews%5Btt_news%5D=148&tx_ttnews%5Bbackpid%5D=1&chash=c92cb6605c>

(german again, pictures on a local fire service page, click on the 
pictures to enlarge (be sure to get the full link above, if it may break 
row in your mail-window))

Markus

-- 

Mit freundlichen Grüßen,
Markus Schlattmann

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schlattmann.de

Dipl.-Ing. agr. Markus Schlattmann
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85416 Langenbach

Tel.: +49 (0)8761 72162-60
Fax.: +49 (0)8761 72162-61

E-Mail: firmen at schlattmann de
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