Gobar Gas Plant construction

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Gobar Gas Plant construction

• Class IX

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Bio gas for village

• Bio gas is a clean unpolluted and cheap source of
  energy in rural areas.  It consists of 55-70
  methane  which is inflammable. Bio gas is
  produced from cattle dung in a bio gas plant
  commonly known as gobar gas plant through a
  process called digestion. 

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Objectives

• 1. To provide fuel for cooking purposes and
  organic manure to rural house holds through
  family type Bio Gas Plants.2. To mitigate
  drudgery of rural women, reduce pressure on
  forests and accentuate social benefits. 3. To
  improve sanitation in villages by linking
  sanitary toilets with bio gas plants.

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Construction Technique Need to keep in Mind

• Site Selection
• Digging of the pit
• Foundation laying 
• Machinery construction work
• Laying of pipeline and accessories
• Precautions in lying pipelines.

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A lay out Model of Gobar gas plant
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Components required for Bio gas plant

• Mixing tank and inlet 
• Digester
• Gas holder or gas storage dome
• Outlet and compost pits and 
• Gas main outlet and valve, pipeline, water
  fittings, gas stoves, lamp and similar appliances
  run on bio gas.

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Feeder (Raw materials) from the Villages

• Cow dung
• Human waste (link latrine to the Gas plant)
• Animal waste
• livestock and poultry wastes, night soil, crop
  residues, food-processing and paper wastes, and
  materials such as aquatic weeds, water hyacinth,
  filamentous algae, and seaweed.

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Construction Process

• First a pit is dug, perhaps ten feet deep. Then a
  water-tight cement cylinder (with brick or
  gravel) is constructed. Next, a wall is built
  across the middle, extending up from the bottom,
  not quite to the top. Intake and outgo pipes are
  installed. The whole unit is water-tight.

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• The manure is mixed with water in the Intake
  basin to make a slurry, which then goes down the
  pipe to the bottom of the left side. This side of
  the cylinder gradually fills and overflows to the
  right side. Meanwhile, the whole mass bubbles
  methane up to the top. It collects under the
  large metal bell-like cover. The gas builds
  pressure, and can be taken off through a rubber
  tube to a gas stove in a kitchen.

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Model of Gas plant
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• When both sides of the cylinder are full, the
  effluent flows out from the bottom of the right
  side each time more raw manure is added to the
  left. What comes out on the right is of more
  value as fertilizer than the raw manure. So the
  methane is an added byproduct literally
  "something for nothing," once the capital expense
  of the construction is paid.

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Cost estimate
Sl. no. Capacity of plant retention period Unit cost
1 1 cu. m 40 days 4700/-
2 2 cu. m 40 days 6500/-
3 3 cu. m 40 days 7600/-
4 4 cu. m 40 days 8700/-
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Subsidy available to Villages
Size of Plant (in cu. m)  Central subsidy for SF, MF AL SC ST Hilly areas Central subsidy for others State subsidy under Anila Yojane SF MF AL SC ST Hilly areas State subsidy for Hilly areas not approved from central government Total
1 2300 1800 1500 2000 3800
2 2300 1800 3500 4000 5800
3 2300 1800 3500 4000 5800
4 2300 1800 3500 4000 5800
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Advantages

• (a) Large cattle population in the countryside
  ensuring steady source of supply of the raw
  material required for running the gas plant.
• (b) Helps in reducing the deforestation as it
  arrests for cutting of trees for firewood.
• (c) Helps in maintaining ecological balance.
• (d) Helps in rural sanitation
• (e) Lower capital cost and almost cost free
  maintenance.
• (f) Removes drudgery of women.

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Uses of Gobar Gas

• Generally the uses of the gas can be as under 1)
  cooking
• 2) lighting
• 3) Motive Power a) run pump set b) chalf-cutter
• 4) can produce electricity. 
• Motive Power can be produced by linking the Gobar
  Gas to a duel fuel engine, specially designed for
  Gobar Gas.

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Courtesy

• http//www.unu.edu/unupress/unupbooks/80434e/80434
  E0k.htm