This set of Air Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Fabric Filters – Set 2”.
1. Which operating conditions can the felted filters not be used?
a) Large particle sizes
b) High abrasive
c) High temperature
d) High humidity
View Answer
Explanation: Felted particles are not used in high humidity operations. This restriction is because the fibre openings can be clogged by moisture and particulates in the gas stream. Other listed options are fibre material dependent.
2. Which of the following factors affects the choice of the fabric for fabric filters?
a) Humidity
b) Operating temperature
c) Operating pressure
d) Load volume
View Answer
Explanation: Of the given options, only operating temperature affects the choice of fabric. Another factor that affects the selection is the corrosiveness of the particulates that need to be separated. Humidity is a special condition for felted fabrics.
3. Which of the following is the least expensive fibre used in fabric filters?
a) Glass
b) Teflon
c) Cotton
d) Wool
View Answer
Explanation: Cotton is the least expensive fabric fibre that can be used in the fabric filtration process. However, it can be used only for low-temperature operations. Teflon is very expensive, and thus, has limited use.
4. Which kind of fabric is used for high operating temperatures of the fabric filters?
a) Silicon-coated glass
b) Nylon
c) Wool
d) Cotton
View Answer
Explanation: Cotton and wool are not used for high-temperature operations. On the other hand, silicon-coated glass fibres are used for high-temperature functioning. Teflon and Nomex nylon are also considered for this purpose.
5. Which type of fabrics can be used to make woven type filters to be used in fabric filters?
a) All fibre types
b) Natural
c) Synthetic
d) Glass
View Answer
Explanation: All fabric types can be used to make woven-type filters. This statement is true for felted type filters as well. The fibres are treated differently to make either of the fabric types and for particular operations.
6. How is the fabric in fabric filters incorporated into the equipment?
a) As sheets of fabric
b) As a bag-like structure
c) As a cavity
d) As a basin
View Answer
Explanation: The fabric is made into a bag-like structure. The gas is allowed into the chambers containing bags, then is forced through the openings in the fabric. The particulates settle here. The clean gas is then directed to the outlet.
7. What is the reason for several baghouses to be provided inside the same filtering equipment?
a) For higher efficiency
b) For ease of operation
c) For continuous operation
d) For easier control
View Answer
Explanation: The primary reason for having multiple baghouses is to ensure continuous operation. In such a case, one baghouse that needs maintenance can be removed while the equipment still operates as usual, and it does not have to be stopped.
8. Which of the following is not an advantage of using fabric filters?
a) High efficiencies
b) Fine particle separation
c) Low pressure drop
d) Small size of the unit
View Answer
Explanation: The fabric filters do not have small sizes; on the contrary, they are large and bulky. Since particles eventually become the primary mode of separation, even fine particles are trapped by the equipment.
9. Which of the following is not a disadvantage of fabric filters?
a) Large size
b) High pressure drop
c) High production costs
d) Application limited by temperature
View Answer
Explanation: Fabric filters offer low pressure drops, unlike the listed option, so this is the odd one out. The operation of fabric filters is limited to below 300 degree Celsius because clothes are temperature sensitive.
10. Which of the following fibres cannot be used in acidic conditions in fabric filters?
a) Cotton
b) Nomex nylon
c) Teflon
d) Polyester
View Answer
Explanation: Among the given options, only cotton has low resistance against acid. Therefore, it cannot be used for the separation of acidic gas and particulates. The other options have relatively high resistance.
11. Which of the following fabrics can be used to trap abrasive particulates?
a) Polyester
b) Cotton
c) Nylon
d) Nomex nylon
View Answer
Explanation: Nylon has high abrasion resistance and can be used for the collection of abrasive and corrosive particles in fabric filters. Wool is also fairly resistant. Other listed options are not preferred to trap such particulates.
12. Which of the following fibres cannot be used for the collection of abrasive particulates?
a) Silk
b) Wool
c) Glass
d) Nylon
View Answer
Explanation: Wool and nylon have a good resistance towards abrasion. However, glass cannot be used for the separation of abrasive solids because of its low resistance. Glass is suitable for high-temperature operations.
13. Which of the following fabrics in fabric filters can be used in a medium of organic solvents?
a) Wool
b) Cotton
c) Glass
d) All fibres are good
View Answer
Explanation: All the fibres (listed and unlisted) have a good resistance towards attacks by organic solvents. For this reason, they can be used for operation as filters when organic solvents are present in the entrained gas.
14. Which of the following is a property of Nomex nylon?
a) Low moisture resistance
b) Easy to clean
c) Low-temperature operation
d) Low resistance towards acids
View Answer
Explanation: Nomex nylon has a low resistance towards moisture and cannot be used under humid operating conditions. It has good acid resistance and can be used for relatively high temperatures of operation.
15. Particulates from which of the following industries cannot be removed using fabric filters?
a) Steel
b) Alumina processing
c) Cement
d) Paper industries
View Answer
Explanation: Fabric filters are not used for the removal of particulates in the paper industry. It is suitable for removing process dust and smoke which is produced in the other listed industries. Paper industries may be abrasive because of sulphurous particulates.
Sanfoundry Global Education & Learning Series – Air Pollution Control.
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