Stationary Source Controls & Source Sampling

1. Stationary Source Controls & Source Sampling Marti Blad Ph.D., P.E.

2. What we will learn • Control of air pollution is possible • Physical, chemical or biological • Control of air pollution is not perfect • “Shell game” • Control mechanisms for particles are different from those that control gasses • Examples of types of controls • How air pollution control devices work • Sampling of point sources

3. Stationary Source Control • Philosophy of pollution prevention • Modify the process: use different raw materials • Modify the process: increase efficiency • Recover and reuse: less waste = less pollution • Philosophy of end-of-pipe treatment • Collection of waste streams • Add-on equipment at emission points • AP control of stationary sources • Particulates • Gases

4. Particulate Control Technologies • Remember this order: • Settling chambers • Cyclones • ESPs (electrostatic precipitators) • Spray towers • Venturi scrubbers • Baghouses (fabric filtration) • All physical processes

7. Settling Chambers • “Knock-out pots” = initial separators • Gravity and inertia forces • Simplest, cheapest, no moving parts • Least efficient & large particles only • Creates solid-waste stream • Can be reused • Pictures on next slides • Baffle, Gravity, Centrifugal

8. Variety of styles

9. Simple boxes= collection

10. Cyclones • Inexpensive, no moving parts • More efficient than settling chamber • still better for larger particles • Single cyclone or multi-clone design • In series or in parallel • Creates solid-waste stream • Picture next slide

12. Notice shapes and fans Dry collection systems

15. Venturi Scrubber Detail illustrates cloud atomization from high-velocity gas stream shearing liquid at throat

16. Venturi Scrubber • High intensity contact between water and gas => high pressure drop • Venturi action modified spray tower • High removal efficiency for small particles • Creates water pollution stream • Can also absorb some gaseous pollutants (SO2)

18. Venturi and scrubbers

19. Spray Towers • Water or other liquid “washes out” PM • Less expensive than ESP but more than cyclone, still low pressure drop • Variety of configurations • Higher efficiency than cyclones • Creates water pollution stream • Can also absorb some gaseous pollutants (SO2)

20. Spray Tower

21. ESPs • Electrostatic precipitator • More expensive to install, • Electricity is major operating cost • Higher particulate efficiency than cyclones • Can be dry or wet • Plates cleaned by rapping • Creates solid-waste stream • Picture on next slide

22. Electrostatic Precipitator Concept

23. Same Size & Shape

24. Electrostatic Precipitator

25. Electrostatic Precipitator

26. Baghouses • Fabric filtration – vacuum cleaner • High removal efficiency for small particles • Not good for wet or high temperature streams • Uses fabric bags to filter out PM • Inexpensive to operate • Bags cleaned by periodic shaking or air pulse • Creates solid-waste stream

27. Pulse-Air-Jet Type Baghouse

29. Baghouse in a Facility

31. Baghouse= fabric filters

33. Stationary Source Controls:Gaseous Pollutants and Air Toxics

34. Source of Gaseous Pollutants

35. Controlling Gaseous Pollutants: SO2 & NOx • Modify Process • Switch to low-sulfur coals • Desulfurize coal • Washing-bioclean • Gasification • Increase efficiency • Low-NOx burners

36. Recover & Reuse Heat • Staged combustion • Multi chambers • Better process control • Flue-gas recirculation • Gas is heat sink • Absorbs heat from high flame area • Lowers peak flame temperatures • Picture next slide

37. How FGR fits in process

38. Controlling Gaseous Pollutants: CO & VOCs • Wet/dry scrubbers • Used for PM but double w wet • Absorber solutions • NOx and SOx included • Combustion Process • Proper operating conditions • Low NOx burners

39. Scrubbers / Absorbers • SO2 removal: “FGD” (flue gas desulfurization) • Lime/soda ash/citrate absorbing solutions • Can create useable by-product OR solid waste stream • NOx removal—catalytic and non-catalytic • Catalyst = facilitates chemical reaction • Ammonia-absorbing solutions • Process controls favored over this technology • CO & CO2 removal • Some VOC removal

40. VOC / CO Process Control • Keep combustion HOT • Reuse & recycle heat • Control cold start-ups, shut-downs, wet inputs • wood-fired, chemical incinerators, boilers • Increase residence time of gas in combustor • Unfortunately, things that reduce NOxtend to increase VOC’s • Atmosphere in air combustion 78% N2

43. How it might look together

44. Flares

45. Thermal Oxidation • Chemical change = burn • CO2 and H2O ideal end products of all processes • Flares (for emergency purposes) • Incinerators • Direct • Catalytic = improve reaction efficiency • Recuperative: heat transfer between inlet /exit gas • Regenerative: switching ceramic beds that hold heat, release in air stream later to re-use heat

46. Thermal Oxidation

47. Actual Oxidizers

48. Regenerative

49. Recuperative

50. Carbon Adsorption • Good for organics (VOCs) • Both VOCs and carbon can be recovered when carbon is regenerated (steam stripping) • Physical capture • Adsorption & Absorption • Bettermarriageblanket.com • Under-tec.com (farty pants)