06-10-2016, 09:30 AM
1457959549-TypesofBiogasPlants.pdf (Size: 244.48 KB / Downloads: 4)
A total of seven different types of biogas plant have been officially recognised by the MNES.
1. the floating-drum plant with a cylindrical digester (KVIC model),
2. the fixed-dome plant with a brick reinforced, moulded dome (Janata model)
3. the floating-drum plant with a hemisphere digester (Pragati model)
4. the fixed-dome plant with a hemisphere digester (Deenbandhu model)
5. the floating-drum plant made of angular steel and plastic foil (Ganesh model)
6. the floating-drum plant made of pre-fabricated reinforced concrete compound units
7. the floating-drum plant made of fibre-glass reinforced polyester.
SmallScaleBiogasDigester
1.Fixed-domePlants
A fixed-dome plant consists of a digester with a fixed, non-movable gas holder, which sits on top of
the digester. When gas production starts, the slurry is displaced into the compensation tank. Gas
pressure increases with the volume of gas stored and the height difference between the slurry level in
the digester and the slurry level in the compensation tank.
The costs of a fixed-dome biogas plant are relatively low. It is simple as no moving parts exist. There
are also no rusting steel parts and hence a long life of the plant (20 years or more) can be expected.
The plant is constructed underground, protecting it from physical damage and saving space. While the
underground digester is protected from low temperatures at night and during cold seasons, sunshine
and warm seasons take longer to heat up the digester. No day/night fluctuations of temperature in the
digester positively influence the bacteriological processes.
The construction of fixed dome plants is labor-intensive, thus creating local employment. Fixed-dome
plants are not easy to build. They should only be built where construction can be supervised by
experienced biogas technicians. Otherwise plants may not be gas-tight (porosity and cracks).
The basic elements of a fixed dome plant (here the Nicarao Design) are shown in the figure below.