Chapter 12. Air Pollution Control CIEG 331 Introduction to Environmental Engineering

Air Pollution Control Gaseous Particulates

Gaseous Pollutants Absorption Adsorption Combustion

Flue Gas Desulfurization (FGD) Non-regenerative: non-recovery and reuse of chemical reagents Regenerative: recovery and reuse of chemical reagents

Non-regenerative systems Chemicals: lime, limestone, caustic soda, soda ash, ammonia SO2 + CaCO3 ---> CaSO3 + CO2 SO2 + Ca(OH)2 ---> CaSO3 + H2O CaSO3 + 1/2 O2 ---> CaSO4 Types Wet Dry

Wet Type Venturi Static packed Moving bed Tray tower Spray towers

Vertical Venturi Scrubber

Packed Bed Scrubber

Dry Scrubber System http://www.fkinc.com/dirctspraydry.htm#top

Control Technologies for Nitrogen Oxides Preventive minimizing operating temperature fuel switching low excess air flue gas recirculation lean combustion staged combustion low Nox burners secondary combustion water/steam injection Post combustion selective catalytic reduction selective non-catalytic reduction non-selective catalytic reduction

Particulate Pollutants Cyclone Filter Liquid scrubbing Electrostatic precipitation (ESP)

Cyclone d0.5 = cut diameter at 50% removal De L3 D2 L1 L2 Dd H B d0.5 = cut diameter at 50% removal m = dynamic viscosity of gas, Pa-s B = width, m H = height, m rp = particle density, kg/m3 Qg = gas flow rate, m3/s q = effective number of turns

For standard Cyclone: B = 0.25 D2 = 0.13 m H = 0.5 D2 = 0.25 m L1 = L2 = 2 D2 = 1 m Ex. 6-9 Given: D2 = 0.5 m Qg = 4 m3/s T = 25 oC rp = 800 kg/m3 Q = What is the removal efficiency for particles with ave diameter of 10 mm? h = 0.95 @ d =10 mm

Cyclone Installation at Wood Working Plant http://www.fkinc.com/cyclones.htm

Air Filtration

Case A: Pore blocking Case B: Pore plugging Case C1: Pore narrowing Case C2: Pore narrowing w/lost pore Case D: Pore bridging

Air Filtration Impaction Diffusion Straining (Interception) Electrostatics

Air Filter High removal efficiency for < 5 mm particles

Scrubber Venturi

ESP

ESP http://www.powerspancorp.com/news/precipitator.shtml

http://www.ppcbio.com/ppcdespwhatis.htm