Question

What is the primary function of baghouse filters in air pollution control?

• A. To remove sulfur dioxide (SO$_2$)
• B. To remove nitrogen oxides (NOx)
• C. To remove particulate matter
• D. To neutralize acidic gases

Hint:

• Baghouse filters (fabric filters) are designed to capture particulate matter (dust, ash, fumes) from gas streams.
• They work by passing the gas through fabric bags that act as filters.
• They are highly efficient for a wide range of particle sizes.
• Gaseous pollutants like SO$_2$, NOx, or acidic gases require different control technologies (e.g., scrubbers, catalytic converters).

Answer 1

The Correct Option is C

Baghouse filters, also known as fabric filters, are air pollution control devices designed to remove particulate matter (PM) from industrial exhaust gases or air streams. Their operation is similar to a vacuum cleaner bag:

• Dirty, particle-laden gas enters the baghouse.
• The gas is forced to pass through a series of long, cylindrical fabric bags (filters).
• The fabric material traps the particulate matter on its surface, allowing the cleaned gas to pass through.
• Over time, a layer of dust (dust cake) builds up on the bags, which actually enhances the filtration efficiency for finer particles.
• Periodically, the collected dust must be removed from the bags using various cleaning mechanisms (e.g., shaking, reverse air flow, pulse-jet cleaning) and collected in a hopper for disposal.

Baghouse filters are highly efficient at removing a wide range of particle sizes, including fine particulates. Options (a), (b), and (d) describe the removal or neutralization of gaseous pollutants, which is not the primary function of baghouse filters. Other technologies are used for these purposes:

• For SO$_2$ removal (option a): Wet scrubbers, dry sorbent injection.
• For NOx removal (option b): Selective Catalytic Reduction (SCR), Selective Non-Catalytic Reduction (SNCR).
• For neutralizing acidic gases (option d): Scrubbers using alkaline solutions.

While some specialized filter media might have sorbent properties for certain gases, the fundamental and primary function of a standard baghouse filter is particulate matter removal. \[ \boxed{\text{To remove particulate matter}} \]