# Energy Engineering Questions and Answers – Types of Biogas Plants – 2

This set of Tough Energy Engineering Questions and Answers focuses on “Types of Biogas Plants – 2”.

1. The ____________ is made of bricks and cement mortar and it’s inside wall are plastered with a mixture of cement and sand.
a) Foundation
b) Digester
c) Gas holder
d) Inlet and outlet pipe

Explanation: Digester (Fermentation chamber) of KVIC is a cylindrical shaped well like structure, constructed using the foundation as its base. The digester is made of bricks and cement mortar and it inside walls are plastered with a mixture of cement and sand.

2. From what material is biogas holder drum made?
a) Mild steel
b) Cast iron
c) Aluminum alloys
d) Rot iron

Explanation: The biogas holder drum of KVIC model is normally made of mild steel sheets. The biogas holder rests on a ledge constructed inside the walls of the digester well. If the KVIC model is made with water jacket on top of the digester wall, no ledge is made and the drum of the biogas holder is placed inside the water jacket.

3. What is the weight of biogas holder?
a) 8-10 kg/m2
b) 10-15 kg/m2
c) 8-18 kg/m2
d) 25-30 kg/m2

Explanation: The weight of the biogas holder is 8-10 kg/m2. The biogas holder of KVIC (Khadi village industries biogas plant) is also fabricated out of fiber glass reinforced plastic (FRP), high density polyethylene (HDP) or Ferroconcrete (FRC).

4. What type of movement does a biogas holder of KVIC has?
a) Linear Movement
b) Transverse movement
c) Rotary movement
d) Circular movement

Explanation: The biogas holder of a KVIC moves up and down on a guide pipe situated in the centre of the digester. The biogas holder has a rotary movement that helps in breaking the scum-mat formed on the top surface of the slurry. The weight of the biogas holder is 8-10 kg/m2. So that it can store biogas at a constant pressure of 8-10 cm of water column.

5. How is the inlet pipe of KVIC made?
a) Cement mortar
b) Asbestos cement concrete
c) White cement
d) PVC

Explanation: The inlet pipe is made out of cement concrete (CC) or Asbestos cement concrete (ACC) or pipe. The one end of the inlet pipe is concrete to the mixing tank and the other end goes inside the digester on the inlet side of the partition wall and rests on a support made of bricks of about 1 feet height.
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6. How is the outlet pipe of KVIC made?
a) Cement mortar
b) Asbestos cement concrete
c) White cement
d) PVC

Explanation: The outlet pipe is made out of cement concrete (CC) or asbestos cement concrete (ACC) or pipe. The one end of the outlet pipe is connected to the outlet tank and the other end goes inside the digester, on the outlet side of the partition wall and rests on a support made of about bricks of about 1 feet height.

7. How is the Biogas outlet pipe of KVIC made?
a) Cement
b) PVC
c) Asbestos
d) GI pipe

Explanation: The biogas outlet pipe is fixed on the top middle portion of the biogas holder, which is made of a small of GI pipe fitted with socket and a gat valve. The biogas generated in the plant and stored in the biogas holder is taken through the gas outlet pipe via pipeline to the place of utilization.

8. What is the life time of Floating drum plant?
a) Short
b) Large
c) Life time
d) Average

Explanation: Even though the floating drum plant is built with all reinforced constituents and hard materials the life of floating drum plant is short which is upto 15 years; And in tropical coastal regions its just about 5 years.

9. Which plant has no movable parts?
a) KVIC
b) JANATA model
c) Pragati design plant
d) Ferro – cement plant

Explanation: The janata model consists of a digester and fixed biogas holder as gas storage chamber covered by a dome shaped enclosed roof structure. The entire plant is made of bricks and cement masonry and constructed underground. Unlike the KVIC, the janata model has no movable part.

10. Which part of the janata bio gas plant comprises of the fermentation chamber and the gas storage chamber?
a) Foundation
b) Digester
c) Inlet chamber
d) Outlet chamber

Explanation: The digester is a cylindrical tank resting on the foundation. The top surface of the foundation serves as the bottom of the digester. The digester of janata biogas plant comprises of the fermentation chamber and the gas storage chamber.

11. The Gas storage chamber of the digester of janata model is designed to store what percentage og daily gas?
a) 5%
b) 19%
c) 33%
d) 58%

Explanation: The gas storage chamber is also cylindrical in shape and is the integral part of the digester and located just above the fermentation chamber. The GSC is designed to store 33% of the daily gas production from the plant.

12. Which plant has fixed hemi-spherical roof?
a) Fixed dome plant
b) Floating drum plant
c) Chinese plant
d) Flexible bag biogas plant

Explanation: Fixed dome plant has a fixed hemi-spherical roof which forms the cover of the digester and constructed with brick and cement concrete mixture, after which it is plastered with cement mortar. The dome is only an enclosed roof designed in such a way to avoid steel reinforcement.

13. The upper portion of the ______________ is in the shape of bell mouth and constructed using bricks and cements mortar in fixed dome plant.
a) gas storage chamber
b) inlet chamber
c) outlet chamber
d) digester

Explanation: The upper portion of the inlet chamber is in the shape of bell mouth and constructed using bricks and cements mortar in fixed dome plant. It s outer wall is kept inclined to the cylindrical wall of the digester so that the feed material can flow easily into the digester by gravity.

14. The outer chamber upper is called as ___________
a) outlet displacement chamber
b) outlet discharge chamber
c) outlet density chamber
d) outlet dwell chamber

Explanation: Outer chamber is a rectangular shaped located just on the opposite side of the inlet chamber. The bottom opening of the outlet chamber is connected to the gate and the upper portion is much wider and is known as Outlet displacement chamber (ODC).

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