Pollution Control Devices Flashcards
Baghouse cleaning mechanism
Filtration
What is the most common type of pollution control?
Baghouse filters
What particle sizes do baghouse filters collect?
> 0.25 microns
Absorber
Liquid picks up gases and absorbs them. Gases counter flow of liquid. Similar to scrubber. Gases and vapors absorbed into liquid. Liquid must be good solvent for gases and vapors. Liquid is recycled.
Adsorber
Vapors and gases adsorbed on surface of porous medium. Does not work at high temperatures.
Condenser
Vapor is passed through cooling coils and condensed liquid is removed.
Cleaning mechanism of cyclones
Centrifugal force
Cleaning mechanism of scrubber
Inertial impingement
Venturi Scrubber
Uses narrowing duct to increase pressure, condensation, and collection efficiency.
- Similar to regular scrubber but liquid spray area is narrower to focus spray.
- The wet particles generally go to bag house.
- High energy costs.
Is a baghouse system or a cyclone system more effective at collecting particles?
Baghouse
What particle sizes do cyclones collect (small diameter)
> 5 microns
What would be the best pollution control for a woodworking shop?
Settling chamber or cyclone
An industrial hygienist (IH) needs to identify and recommend a pollution control device for exhaust gases and vapors of a very hot and humid process. Which of the following devices would be the best choice?
A. Absorber
B. Adsorber
C. Baghouse
D. Venturi scrubber
A baghouse and venturi scrubber are both used to control particulates, not gases or vapors. Adsorbers, like adsorbent sampling tubes, do not work well at high temperature or high humidity.
Max baghouse temperature
550F
Cleaning mechanism for venturi scrubber
Inertial impingement and centrifugal force
Cleaning mechanism for electrostatic precipitator
Electrostatic attachment
Particle size that electrostatic precipitators collect
> 0.25 um
Particle size that a venturi scrubber collects
> 1 um
Best pollution control device for gases/vapors in a hot/humid process
Absorber
Best pollution control device for a combustible dust
Wet scrubber
Which pollution control devices capture particulates >1um
Venturi scrubber
Which dust collection method is best for plastic extrusion machines
Electrostatic precipitator
Which pollution control device can capture small particles (>0.25 um) with minimal pressure drop?
- Electrostatic precipitator
- Pressure drop is 0.5 in h2o (whereas baghouse is 3-6 in h20)
