design and design choice parameter of medium sized biogas ... · design and design choice parameter...
TRANSCRIPT
Feeding Material for Biogas Production
– All the biodegradable material
– Cattle dung
– Kitchen waste
– Human excreta
– Municipal waste
– Chicken droppings
– Green grasses
– Agricultural residues
– Other animal waste
Necessary Parameters
Resource
Biogas Technology
User
Technical parameters
Climatic Conditions
Time and movement
Family Size/Generator capacity
Food HabitsCooking Habits
Income level
Habits
Fuel and Cooking Device Preferences
Necessary Technical parameter for Biogas Production
Biogas
Anaerobic
Condtion
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
pH level
Optimum gas production – pH of inputmixture is 6-7
Temperature
The activity of bacteria largely dependsupon temperature.
Appropriate Temp. – 150C to 350C
The methanogenes are inactive inextreme high and low temperature.
Loading rate• Amount of raw material fed to the
digester per day per unit volume of digester capacity
• Incase of cow dung digester, the thumb rule is to put 6-8 kg of fresh dung for 1 m3 size of bio-digester.
• Correct rate of loading is essential for efficient gas production
• If plant is over fed, acidity will accumulate and methane production will be reduced.
• If loading rate is low, gas production will be reduced.
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
Retention Time• Average duration of time a simple
remains in the digester.
• For a cow dung plant, 40- 60 days is required, depending upon temperature.
• Volume of digester should be equal to 40 – 60 times the feed added daily.
• For a night soil digester, a longer retention time (70-90 days) is needed in order to kill the pathogens present in human faces.
daily added Feed of Volume
digester of volumeTotaltimeRetention
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
Carbon Nitrogen (C/N) ratio• For proper functioning of micro-
organism, both carbon andnitrogen is needed inside thedigester.
• C/N ratio – 20-30:1 is consideredbest for anaerobic digestion.
• If C/N is high – nitrogen will beconsumed rapidly leading todecrease in rate of reaction
• If C/N is low – nitrogen will beliberated and accumulated in theform of ammonia, which is toxic.
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
SN Raw Material C/N Ratio
1 Duck Dung 8
2 Human Excreta 8
3 Chicken dung 10
4 Goat dung 12
5 Sheep dung 19
6 Cow / Buffalo dung 24
7 Water hyacinth 25
438 Elephant dung
609 Straw (Maize)
10 Straw (Rice) 70
9011 Straw (wheat)
Above 20012 Saw dust
C/N ratio of some organic material
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
Dilution or Agitation• Before feeding the digester,
excreta such as fresh cowdung has to be mixedthoroughly with water.
• 1:1 on volume basis is used.
Anaerobic Condition• Digesters should be airtight
to maintain strictly anaerobiccondition
Biogas
Anaerobic
Condition
pH
Temperature
C/N ratioAgitation
Loading Rate
Retention Time
Necessary Conditions for Biogas Production (Contd….)
What about Biogas Generation from any organic substances?
S.N. Parameter Value
1 C/N Ratio 20 – 30
2 PH 6 – 7
3 Digestion temperature 20 – 35
4 Retention time (HRT) 40 –100 days
5 Biogas energy content 6 kWh/m3
6 One cow yield 9 – 15 kg dung/day
7 Gas production per kg of cow dung 0.023 – 0.04 m3
8 Gas production per kg of chicken dung 0.065 – 0.116 m3
9 Gas production per kg of human excreta 0.020 – 0.028 m3
10 Gas requirement for cooking 0.2 – 0.3 m3/person
11 Gas requirement for lighting one lamp 0.1 – 0.15 m3/hr
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Schematic Layout of the Biogas System and its different components for Hotels/Institutional/Dairy farm/waste recovery
But For Piloting case just focus on 1:1 Dung water feeding in Pakistan