[Digestion] feedbag-type digester slopes

[Jaime Marti Herrero]

Hi warren
The slope is recomend to be 0. you can have as much 5-10% slope.
The
manure will be mixed wth water on 1:3 (if it is vcow manure, 1:4 if
pig) so it is really flluid the mud inside the biodigester.
if you have 10 m biodigester, yo have to know the diameter or radio of the system. You need to know the volume.
once
you know the volume, 1/4 of it will be for the biogas bell on the upper
part of the biodigester, so ypou will have 3/4 of the total volumen for
liquid part.
This liquid volume you have to divide between the load
of  manure plus water that you will put insedie the biodigester every
day. So if you do this, you will get the retention time. If you add
more load manure:water the retention time will reduce.
You have to get a longitude:diameter rate of 1:5 - 1:10, and the best rate is 1:7.5.

The retention time (RT) depends on the ambient temperature of the place where the biodigester is gonna work. I recomend:
Min ambient temp.        Mean ambient Temt        Retention time
   -10ºC                                                4-12ºC                        75 days
   1ºC                                                  12-20ºC                    37 days
    10ºC                                                20-30ºC                    25 days

So
once you know the RT, you need too know the manure that you want to
introduce in the biodigester every day (every kg of cow manure will
produce 35 liters of biogas). With the amount of manure yo plus the
water need to mix it (1:3). this will bee your daily load. you have to
multiplay the daily load with the RT, and you get the liquid volume of
the biodigester.
Know you have to add the biogas bell: this is 1/3
of the liquid volume(the total volume is 1/4 of biogas bell and 3/4 of
liquid volume) , so you will get the total volume of the biodigester.
Now you know the  total volume, yo have to find the best relation between the diameter and longitude to get 1:7.5 rate.

You can send your design and i will help you if you want.
Kind regards
Keep in contact
jaime



> Date: Sun, 25 May 2008 15:33:50 -0700
> From: weiswar at yahoo.com
> To: digestion at listserv.repp.org
> Subject: [Digestion] feedbag-type digester slopes
> 
> 
> Hey all, 
> 
> With feedbag-type digesters like the ones in the video
> from Bolivia what slope is the trench cut at in order
> to move the effluent through? Obviously we can control
> the retention time with the angle, does anyone know
> how long of a retention time would be for a 10 meter
> long feedbag digester? 
> 
> Thanks Warren 
> 
> 
>       
> 
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> http://www.adelaide.edu.au/biogas/
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