Feedstock prep, what sort of pump?

Digester design and construction info

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farmer
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Feedstock prep, what sort of pump?

Postby farmer » Sat Feb 16, 2008 4:43 am

Hi gang. I am looking at using food waste, leaves, and crude biodiesel glycerol to feed my digester, but I think this application could also apply to human waste and other feedstocks.

What sort of prep are you doing on the front end? Would passing the feedstocks through a garbage disposal be effective mastication?

I am also trying to picture a pump that will move this stuff into the digester with enough force to stir the pot, as in Bob's Biorealis design. I know that my centrifugal water pumps and gear pumps would not take this treatment. The best I can come up with so far is an inner tube that is manually squeezed, like an esophagus...

Thanks for your feedback~!

Farmer

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Bob
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Postby Bob » Fri Feb 29, 2008 4:12 pm

What sort of prep are you doing on the front end? Would passing the feedstocks through a garbage disposal be effective mastication?

I use a diaphragm pump -- commonly use for RV or boat holding tanks. But if the feedstock is fibrous, it will be a maintenance headache. And a nasty one. The extra energy required to grind, chop or macerate it to make it pumpable has to be subtracted from the bottom line.

The best I can come up with so far is an inner tube that is manually squeezed, like an esophagus...

Yep. They are called peristaltic pumps. But the same issues apply. Fibrous stuff just does not lend itself well to pumping. If that is the feedstock, some other system -- e.g. a batch/continuous feed 'hybrid' would probably work better. In these systems you have multiple 1st stage acidogenic digesters that are batch fed, and then the effluent from them is pumped into the methanogenic phase digester.


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