Page 102 - Plant design and economics for chemical engineers

TABLE 8
3 Air pollution control equipment characteristics
Optimum? Optimum
size concen- Tempera- Pressure Space
Control particle, tration, ture limi- drop, Effi- require- Collected
equipment microns grains / ft3 tations, “F in. H,O ciency ments$ pollutant Remarks
Particulates pollutant
Mechanical collectors
Settling chamber > 50 >5 < 0.1 <50 L Dry dust Good as precleaner
Cyclone 5-25 >1 1-5 5 0 - 9 0 M Dry dust Low initial cost
Dynamic precipitator > 10 >l Fan <80 M Dry dust
Impingement separator > 10 >l <4 <SO S Dry dust
Bag filter <I > 0.1 >4 >99 L Dry dust Bags sensitive to humidity, filter
velocity, and temperature
Wet collector
Spray tower 25 >1 40-700 0.5 <80 L Liquid Waste treatment required
Cyclone >5 >l 40-700 >2 <80 L Liquid Visible plume possible
Impingement >5 >1 40-700 >2 <80 L Liquid Corrosion
Venturi <l > 0.1 40-700 1-60 < 99 S Liquid High temperature operation possible
Electrostatic precipitator <I > 0.1 850 <l 9 5 - 9 9 L Dry or 1 Sensitive to varying condition and
wet dust particle properties
Gaseous pollutant
Gas scrubber > 1% 40-100 < 10 >90 M-L Liquid Same as wet collector
Gas adsorber 8 40-100 < 10 >90 L Solid or Adsorbent life critical
liquid High initial and operating cost
Direct incinerator Combustible 2000 <I <95 M None High operating costs
vatxxs
Catalytic combustion >1 <95 L None Contaminants could poison catalyst
vapors
t Minimum particle size (collected at approximately 90% efficiency under usual operating conditions)
$ Space requirements: S = small, M = moderate, L = large
8 Adsorber (concentrations less than 2 ppm non-regenerative system; greater than 2 ppm regenerative system)