HOW TO START UP AND RUN A BIO GAS PLANT
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STARTING UP A BIO GAS PLANT
POST NUMBER :08 Date : 02/05/2004
BIO GAS PLANT PROCESS DESCRIPTION:
Biotechnology process
stage one : hydrolysis by hydrolytic bactaria, conversion of extracellular molecules
stage two : thermophilic fermentation based on carbohydrates
stage three : synthesis of volatile fatty acids by acetogenic bacteria
stage four : synthesis of methane by methanogenic organisms
STARTING UP A BIO GAS PLANT:
OPERATION OF BIO GAS PLANT
FLOW CHART: CRUSHER(less than 7mm particle size)----thermophilic Aerobic digester(Temp 55 degree C )---Mesophilic Anaerobic Digester(37 Degree C )---Manure Pit
POST NUMBER :08 Date : 02/05/2004
BIO GAS PLANT PROCESS DESCRIPTION:
STARTING UP A BIO GAS PLANT:
Aspect
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Bottlenecks
|
Remarks
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CONTROLS
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Check for Gas leaks
|
Check hood , pipe etc. Monthly checking of leakage by pressure system and or with soap water
|
Cow dung slurry
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Make slurry of cow dung and fresh water in the ratio 2kg dung 15 liter water (thumb rule 10% dung of water volume). Fill up the bio digester with the slurry.
| |
Slurry fermentation
|
Wait for slurry to form gas. It normally takes 3 to ten days.Gas formation can be seen by rising of floating dome or pressure gauge in fixed dome.
| |
Start of Feeding
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Start fresh feeding after formation of gas. Start with small quantity of feed material in 1:1 ratio. After 15 days, start feeding full capacity.
| |
Complete Release of first gas produced
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Gases should be released to the atmosphere at least three times at a gap of three days each.
It may be needed to be released more till methane percentage of 60% reached .Do a sample bio gas test to know exact position of gas produced.
| |
Technical
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Improper preparation of influent solids
leading to blockage and scum formation
|
Proper milling and other treatment measures (pre-
soaking, adjustment of C/N ratio); removal of inert
particles: sand and stone.
|
Temperature fluctuations
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Careful regulation of temperature through use of
incorporation of auxiliary solar heating system.
| |
Maintenance of pH for optimal growth of
Methanogenic bacteria
C/N ratio
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Appropriate choice of raw material, regulation of
C/N ratio and dilution rate.
Appropriate mixing of N-rich and N-poor
substrates with cellulosic substrates.
| |
Dilution ratio of influent solids content
|
Appropriate treatment of raw materials to avoid
stratification and scum formation.
| |
Retention time of slurry
|
Dependent upon dilution ratio, loading rate,
digestion temperature.
| |
Loading rate
|
Dependent upon digester size, dilution ratio,
digestion temperature.
| |
Seeding of an appropriate bacterial
Population for biogas generation
|
Development of specific and potent cultures.
| |
Corrosion of gas holder
|
Construction from cheap materials (glass fibre,
clay, jute-fibre reinforced plastic) and/or regular
cleaning and layering with protective materials
(e.g., lubricating oil).
| |
Pin-hole leakages (digester tank, holder,
inlet, outlet)
|
Establishment of "no leak" conditions, use of
external protective coating materials (PVC,
creosotes
| |
Occurrence of CO2 reducing calorific
value of biogas
|
Reduction in CO2 content through passage in
lime-water
| |
Occurrence of water condensate in gas
supply system (blockage, rusting)
|
Appropriate drainage system using condensate
traps
| |
Occurrence of H2S leading to corrosion
|
On a village scale, H2S removed by passing over
ferric oxide or iron filings
| |
Improper combustion
|
Proper air gas mixing appliances necessary
| |
Maintenance of gas supply at constant
pressure
|
Regulation of uniform distribution and use of gas;
removal of water condensate from piping systems;
appropriate choice of gas holder in terms of weight
and capacity
| |
Residue
utilization
|
Risks to health and plant crops resulting
from residual accumulation of toxic materials
and encysted pathogens
|
Avoid use of chemical industry effluents; more
research on type, nature, and die-off rates of
persisting organisms; minimize long transportation
period of un-dried effluent
|
Health
|
Hazards to human health in transporting
night soil and other wastes (gray-water)
|
Linkage of latrine run-offs into biogas reactors
promotes non-manual operations and general
aesthetics
|
Safety
|
Improper handling and storage of methane
|
Appropriate measures necessary for plant
operation, handling, and storage of biogas through
provision of extension and servicing facilities
|
DO NOT USE eggshells, Onion peels or left-over bones in this system as they will affect the efficient functioning of the system
Hazards: Methane in a concentration of 6 to 15 percent with air is an explosive mixture. Since it is lighter than air, it will collect in rooftops and other enclosed areas. It is relatively odorless and detection may be difficult. Extreme caution and special safety features are necessary in the digester design and storage tank
POSTED BY SALEEM ASRAF SYED IMDAADULLAH AT 5/02/2004 11:13:00 PM
Cost details, saving and payback period from a biogas plant:
The cost details and the savings envisaged from the plant are given in the following table. The life of the plant could be 20-30 years and payback period is 4-5 years.
Capacity (Tons / Day)
|
Installation Cost (Rs In Lacks)
|
Monthly Operation and Maintenance Charges (Rs)
|
Methane Generation M3
|
Manure production (tons /day)
|
Area Required M2
|
Power
|
Manpower
|
Fresh Water (KL /day)
|
Hot water (Ltr / day of 50-60 C0)
|
Cooking Fuel (Equivalent to LPG Cyl / day)
|
1
|
8-10
|
8,000/-
|
100-120
|
0.1
|
300
|
5hp(2hr)
|
2
|
2
|
200
|
2-3
|
2
|
10-12
|
12,000/-
|
200-240
|
0.2
|
500
|
5hp(3hr)
|
3
|
3
|
400
|
4-5
|
4
|
20-22
|
22,000/-
|
400-480
|
0.3
|
700
|
5hp(3hr)
|
4
|
5
|
400
|
8-10
|
5
|
28-30
|
30,000/-
|
500-600
|
0.5
|
800
|
10hp (4hr)
|
5
|
7
|
600
|
12-14 (25Kw)
|
10
|
65-70
|
50,000/-
|
1000-1200
|
2.5
|
1200
|
15hp (4hr)
|
10
|
15
|
1000
|
22-25 (50Kw)
|
* This is an approximate cost for biogas generation plant and may increase by 10%–20%, depending on location, site-specific parameters, cost of materials, labour cost, etc., in different states/cities. Cost of additional infrastructure like office space, toilets, security, Godown, Shades and power generation will be extra, if required.
Rs – rupees; m3 – cubic meters; m2 – square meters; h – hour; kL – kilolitre; LPG – liquefied petroleum gas; kW – kilowatt; cyl –
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