This set of Energy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Types of Biogas Plants – 1”.
1. Which types of plant are fed and emptied regularly?
a) Batch type plants
b) Continuous type plants
c) Dome type plants
d) Drum type plants
View Answer
Explanation: Continuous plants are fed and emptied continuously. They empty automatically through the overflow whenever new material is filled in. therefore, the substance must be fluid and homogeneous.
2. Gas production of continuous plant is higher than which of the following plant?
a) Batch plant
b) Dome plant
c) Drum plant
d) Flexible gas biogas plant
View Answer
Explanation: Continuous plants are suitable for rural households as the necessary work fits well into daily routine. Gas production is constant and higher than in batch plants. Today, nearly all biogas plants are operating on a continuous mode.
3. What type of plant is a floating gas holder plant?
a) Batch plant
b) Continuous plant
c) Semi-batch plant
d) Semi-continuous plant
View Answer
Explanation: This is one of the common designs in India, coming under category of semi-continuous feed plant. It has a cylindrical floating biogas holder on top of the well shaped digester. This digester is vividly used in rural sides.
4. For how much percent is biogas normally designed to hold?
a) 35%
b) 20%
c) 50%
d) 80%
View Answer
Explanation: As the biogas is produced in the digester, it rises vertically and gets accumulated and stored in the biogas holder at a constant pressure of 8-10 cm of water column. The biogas holder is normally designed to store 50% of the daily gas production.
5. Where was fixed dome concept plant developed?
a) China
b) America
c) India
d) Japan
View Answer
Explanation: The plant based on fixed dome concept was developed in India in the middle 1970s. The Chinese fixed plants use a seasonal crop wastes as the major feed stock for feeding, therefore, their design is based on principle of semi-batch-feed digester.
6. Indian fixed dome digesters are designed for holding what pressure capacity?
a) 0 – 90 cm of water column
b) 70 – 90 cm of water column
c) 50 – 65 cm of water column
d) 10 – 25 cm of water column
View Answer
Explanation: The Indian fixed dome plant design use the principle of displacement of slurry inside the digester for storage of biogas in the fixed gas storage chamber. Indian fixed dome biogas digesters are designed for pressure inside the plant varying from 0 to 90 cm of water column.
7. Fixed dome biogas plant is best suitable for which type of plant?
a) Continuous type
b) Batch type
c) Semi-batch type
d) Semi continuous type
View Answer
Explanation: The discharge opening is located on water wall surface of the outlet displacement chamber and it spontaneously controls the maximum pressure. It is best suited for batch process especially when daily feeding is adopted in small quantities.
8. Which plants digester is fabricated by using rubber?
a) Flexible Bag biogas plant
b) Fixed dome biogas plant
c) Floating drum biogas plant
d) Khadi and village industries type biogas plant
View Answer
Explanation: Main unit of the plant including the digester is fabricated by using rubber, high strength plastic, neoprene or red mud plastic. The inlet and outlet are made of heavy duty PVC tube. A small pipe of same PVC tube is fixed on top of the plant as gas outlet pipe.
9. Which type of plant is portable?
a) Flexible Bag biogas plant
b) Fixed dome biogas plant
c) Floating drum biogas plant
d) Khadi and village industries type biogas plant
View Answer
Explanation: Flexible bag biogas plant is portable and can easily be erected. It requires support from outside, upto the slurry level, to maintain the shape as per its design configuration, which is done by placing the bag inside a pit dug on site.
10. In which type of plant the weight needs to be added on top to build the desired pressure?
a) Flexible Bag biogas plant
b) Fixed dome biogas plant
c) Floating drum biogas plant
d) Khadi and village industries type biogas plant
View Answer
Explanation: The depth of the pit should be in proportion to height of the digester so that the mark of initial slurry level is in line with the ground level. The outlet pipe is fixed in such a way that its outlet opening is also in line with the ground level. Some weight has to be added on the top of the bag to build the desired pressure to convey the generated gas to the point of utilization.
11. What is the main advantage of flexible bag plant?
a) The fabrication can be centralized for mass production
b) It has highest gas storage capacity
c) It is portable from place to place
d) Easy to understand and work on it
View Answer
Explanation: Advantage of flexible bag plant is that the fabrication can be centralized for mass production. Individuals or agencies having land and basic infrastructure can take up fabrication of the biogas plant with small investment.
12. Khadi village industries type biogas plant is example of _________
a) flexible Bag biogas plant
b) fixed dome biogas plant
c) floating drum biogas plant
d) semi-batch type
View Answer
Explanation: Khadi and village industries type biogas plant (KVIC) is an example of Floating drum biogas plant. It is a semi continuous plant. It is one of the most common types of biogas plant used in rural area of India.
13. Vertical type KVIC is more commonly used than horizontal type.
a) True
b) False
View Answer
Explanation: The KVIC (Khadi and village industries biogas plant) model is a floating holder semi continuous fed bio gas plant and has two types, (I) Vertical and (II) Horizontal. The vertical type is more commonly used and the horizontal type is used only in the high water table region.
14. Which part of the KVIC is made of mixture of cement concrete and brick ballast?
a) Foundation
b) Digester
c) Gas holder
d) Inlet and outlet pipe
View Answer
Explanation: Foundation of a KVIC is compact base made of a mixture of cement concrete and brick ballast. The foundation is well compacted using wooden ram and then top surface is cemented to prevent any percolation & seepage.
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