This set of Air Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Gaseous Pollutants – Control of Hydrocarbons”.
1. Which of the following is not one of the four techniques used to reduce hydrocarbon emissions?
a) Incineration
b) Adsorption
c) Absorption
d) Catalytic reduction
View Answer
Explanation: Catalytic reduction is not a technique used to reduce emissions of hydrocarbons. The four methods are incineration, adsorption, absorption, and condensation. The choice of method is made based on the constituents of the emissions.
2. Which method has a high removal efficiency for hydrocarbons?
a) Condensation in gravity settlers
b) Flame afterburner method
c) Adsorption with molecular sieves
d) Absorption with benzene
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Explanation: The flame afterburner method of incineration has high hydrocarbon removal efficiencies. Although the other listed techniques are viable for hydrocarbon emission reduction, the materials (molecular sieves, benzene) are not preferred.
3. Which of the following is not a disadvantage of using the flame afterburner method for hydrocarbon recovery?
a) Emits NOx
b) Emits CO
c) Expensive heat recovery
d) Emits CO2
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Explanation: The flame afterburner method has high removal efficiencies for hydrocarbons. It is a type of incineration. However, it has many disadvantages. The process may emit NOx and CO, and the equipment may be expensive.
4. For the recovery of hydrocarbons, what is the advantage of using the catalytic afterburner method over the flame afterburner method?
a) Emissions of NOx are less
b) Emissions of CO are less
c) Efficiencies are higher
d) Maintenance required is less
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Explanation: The catalytic afterburner method uses a catalyst for the process. The main advantage of this method is that the production and emission of nitrogen oxides are lower. Additionally, the fuel costs are lower as well.
5. For the recovery of hydrocarbons, what is the advantage of the flame afterburner method over the catalytic afterburner method?
a) Efficiencies are much higher
b) NOx emissions are lower
c) Equipment is expensive
d) Heat recovered is less
View Answer
Explanation: The main advantage of the flame afterburner method is that it has higher recovery efficiencies than the catalytic afterburner method. However, its disadvantages include higher NOx emissions, and the equipment is expensive.
6. Which of the following temperature falls into the range of the ideal operating temperature condition of adsorption when recovering hydrocarbons?
a) 25 degrees Celsius
b) 45 degrees Celsius
c) 65 degrees Celsius
d) 85 degrees Celsius
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Explanation: Adsorption of hydrocarbons to remove them from the emission stream occurs at relatively low temperatures. The range of temperature operation is between 30 and 60 degrees Celsius. Among the given options, only 45 degrees Celsius falls in this range.
7. Which of the following is the preferred adsorbent used for the adsorption of hydrocarbons?
a) Molecular sieves
b) Manganese oxide
c) Alkalised alumina
d) Activated carbon
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Explanation: Among the given options, only activated carbon is preferred for the adsorption of hydrocarbons from flue gases. The adsorbent grains have diameters less than 5 mm. The adsorbers themselves are operated in parallel.
8. Which statement about the absorption of hydrocarbons from emission streams is true?
a) The equipment is expensive
b) It is not effective at capturing hydrocarbon fumes
c) Water is used as an absorbent
d) Activated carbon is a viable absorbent
View Answer
Explanation: Water can be used for the absorption of hydrocarbon vapours. However, it can only be done when the hydrocarbon in question has a high solubility in water. Activated carbon is a viable adsorbent, not an absorbent.
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.
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