[Digestion] Sizing a flexible balloon digester

Jaime Marti Herrero tallerbiogas at hotmail.com
Mon Apr 30 14:07:20 CDT 2012



hi vianneyjust as exampleRetention time:40 daysmanure to be load per day: 30 kg/dayRatio manure:water= 1:3 (recomended for cow manure, if it is pig manure use 1:4)water to be load: 30x 3= 90 l/daytotal load: 30+ 90=120 l/dayLiquid volume of digester= 120 x 40=4800 liter=4.8m3% biogas volumen respect total volume= 20%so the digester is 4 parts of liquid and 1 part of biogas sobiogas volume= 4800/4=1200 literTotal digester volume=4800+1200= 6000 liter
Yo can decide to have 20% of biogas volume , or 25%, or 50%, etc. i recomend 20%. that is enoughtbut the main issue is to calculate the liquid volume. after this, you can use this paper ( Design methodology for low cost tubular digesters http://www.sciencedirect.com/science/article/pii/S0960852411018979)to find the better dimensions for the ditch, depending the circufenre of your plastic, the angle of the ditch walls, and the % of biogas bell you want.i hope this helpskeep in touchjaime
-----
Jaime Martí Herrero

Technical advisor of biogas for the GTZ-Bolivia
CIMNE (www.cimne.com)
Building Energy and Environment Group
International research cooperation area
La Paz · Bolivia
Tel. (+591)-73 090 621
 

BIOGAS AND BOLIVIA
-Taller Biogas Bolivia
http://tallerbiogas.blogspot.com  
-Video: Biodigester installation in bolivian Altiplanohttp://www.youtube.com/watch?v=TdmJXDiqu44
http://es.youtube.com/watch?v=3Sl0XEN5Bgo
http://www.youtube.com/watch?v=Vs0JuV8WD_c
-Manual gratuito-Biodigestores familiares: Guía de diseño y manual de instalación
http://grecdh.upc.edu/publicacions/llibres/documents/2008_jmh_guia_biodigestores.pdf

From: trustvianney at gmail.com
Date: Mon, 30 Apr 2012 11:54:50 -0700
To: digestion at lists.bioenergylists.org
Subject: [Digestion] Sizing a flexible balloon digester

Guess all is well. 
Sizing a biogas unit

The size of the digester, i.e. the digester volume Vd, is determined on the basis of the chosen retention time RT and the daily substrate input quantity Sd. For a simple digester design, the retention time should amount to at least 40 days

RT = retention time = 40 daysSd = daily substrate quantity = manure plus water

Volume of digester, Vd = Sd × RTThe ratio Vd ÷ Vg (digester volume ÷ gasholder volume) is a major factor when designing a biogas digester. For a typical agricultural biogas plant, the Vd/Vg-ratio amounts to somewhere between 3:1 and 10:1, with 5:1 - 6:1 occurring most frequently.

 Volume of gas (Vg) = 1/3VdTotal volume required = Vd + Vg

I need to estimate the volume of the flexible balloon digester (using the above equations) which would be installed in different households. The

 daily feedstock, volume of biogas storage and retention time being the determinant factors. Retention time was however fixed at 40 days. 






I will be glad to get guided. 




Thanks in advance

. 
Best regards,


-- 
Vianney Tumwesige
Director - Green Heat (U) Ltd  


P.O. Box 10235
Kampala-Uganda
256 (0) 71 237 9889



"The more people are self sufficient in cooking fuel, the more personal and financial freedom they have." - Emma Casson







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