This set of Air Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Fabric Filters”.
1. Which method of collection is the oldest and considered the most viable and efficient at removing particulate matter?
a) Gravity settlers
b) Electrostatic precipitators
c) Cyclone separators
d) Filtration
View Answer
Explanation: The filtration technique is known to be the most adaptable and efficient at removing particulates from industrial gases. This method of removal uses packed fibre to exert a driving force for the separation.
2. On what basis are filters classified into packed or fabric filters?
a) Based on whether the filters are made of cloth
b) How the fibres are held in place
c) The thread count
d) How the gas impacts the filters
View Answer
Explanation: The filters are classified into packed and fabric based on the way the fibre is packed. In the case of the packed filter, the fibres are packed loosely. In the case of the fabric filter, the fibres are made into fabric.
3. How are the fibres packed in the packed filters?
a) Fibres are not used
b) Into a fabric
c) Loosely packed in a conduit
d) As a sheet
View Answer
Explanation: In the packed filters, the fibres are packed into a conduit. The entrained gas travels through the fibres in the conduit, where the fibres capture the particulates. The chamber is rectangular in nature, so the gas has a long path to travel before it can exit.
4. How are the fibres packed in the fabric filters?
a) Into a fabric
b) Fibres are not used
c) Loosely packed in a conduit
d) As a sheet
View Answer
Explanation: In the case of the fabric filter, the fibres are woven into a fabric. Then the material is made into a bag, which traps the particulates. Fabrics can be natural or synthetic, or even metallic, based on the application.
5. Where do fabric filters find most of their applications?
a) In industrial separation
b) Air conditioning
c) Domestic purposes
d) Power plants
View Answer
Explanation: Fabric filters mostly find their applications in the industrial particulate collection. Their efficiencies are very high, ranging up to 99.9% in some cases. The fabric can be made of metal, natural or synthetic fibres, and even glass.
6. Of the given options, where are packed filters used most commonly?
a) In industrial separation
b) Air conditioning
c) Domestic purposes
d) Power plants
View Answer
Explanation: Packed filters are used commonly in air-conditioning since the size of the dust particles is minute, and usually dust. The particulates are captured readily by the fibres in the packed filter.
7. Which of the following is not a mechanism of separation employed in packed filtration?
a) Direct interception
b) Inertial impact
c) Gravity settling
d) Diffusion
View Answer
Explanation: Among the given options, only gravity settling is not employed in the particulate collection by packed filters. Particulate inertia causes interception and impaction. Here, minute particles get diffused.
8. Why is the initial efficiency of the fabric filters so low?
a) The load capacity is less than nominal
b) The particulates are very small
c) The statement is false
d) The fabric openings are large
View Answer
Explanation: The initial efficiency is low because the openings in the woven fabric are much larger than the particulate size. This trait allows the particles to pass through. With time, however, as more and more particles are captured, the efficiency increases.
9. The fabric filters have low initial efficiency because of the improper selection of fabric.
a) True
b) False
View Answer
Explanation: The collection efficiency of the fabric filters is low initially because the particulate sizes are minute. The fabric openings are large enough to allow the particulates to pass through. The efficiency increases as more and more particulates are trapped.
10. What is the usual operating efficiency of fabric filters?
a) 99%
b) 95%
c) 80%
d) 75%
View Answer
Explanation: Fabric filters have very high efficiencies. As the fabric traps numerous particles, the efficiency increases rapidly, with the typical efficiency of the collection being 99%. Some filters have efficiencies as high as 99.9%.
11. After operating for some time, what is the primary medium of separation in fabric filters?
a) The gas
b) The fabric
c) The collected particles
d) The equipment walls
View Answer
Explanation: Over time, the primary driving force of the operation becomes the previously collected particulates. This situation is the reason for improved high operating efficiencies of the device. It is also the reason why frequent maintenance is essential.
12. Why do fabric filters need regular maintenance?
a) The gas
b) The fabric
c) The collected particles
d) The equipment walls
View Answer
Explanation: The collected particles-which increase the efficiency of the fabric filters-are the reason for the drop in efficiency. The device needs to be cleaned, but a layer of the collected particles should be allowed to remain. It is to ensure that efficiency does not drop entirely.
13. What is the fabric filter classification based on?
a) Fibre count
b) Fabric medium
c) Fabric preparation
d) Thread count
View Answer
Explanation: Fabric filters are classified into two categories based on the medium of the fabrics used. These are: woven fabric type and felt fabric type. All the materials used to make the filters can be woven or felted.
14. What are the two classifications of fabric filters?
a) Woven and felt
b) Woven and piled
c) Felt and piled
d) Piled and knitted
View Answer
Explanation: The two types of classifications are woven-typed and felted-type. All the fabric fibres that are used to make the separation medium can be either woven or felted, based on the application and suitability.
15. What is an advantage of the felted type fabric when used in the fabric filters?
a) Do not clog easily
b) They can withstand higher humidity conditions
c) Less expensive
d) Loading requires less cloth coverage
View Answer
Explanation: The main advantage of the felted type fabrics is that they require a lesser cloth area when loading when compared to the woven type. This advantage reduces the number of resources needed.
Sanfoundry Global Education & Learning Series – Air Pollution Control.
To practice all areas of Air Pollution Control, here is complete set of 1000+ Multiple Choice Questions and Answers.
If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]
