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EPA Emission Factors

EPA Emission Factors. Example : Emissions From Bituminous Coal CombustionObtain Activity Rate: Coal Flow rate in this case. Lookup Emission Factors for Specific Class of PollutantsParticulate Emissions = EFparticulates x Coal Flow RateSO2 Emissions = EFSO2 x Coal Flow RateNOX Emissions = E

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EPA Emission Factors

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    1. EPA Emission Factors Emission Testing is Expensive For Well defined sources (e.g. stacks)- Tedious but not difficult For Poorly defined sources (e.g.dust from unpaved roads or forest fires) – Difficult to estimate For unknown or new sources - difficult Emission Factor Approach attempts to address these (EPA document AP-42, 1991) http://www.epa.gov/ttn/chief/ap42/ Emissions factor a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant General Equation for Emissions Estimation: E = EF x A x (1-ER/100) E = emissions (mass of pollutant/unit quantity of activity) A = Activity rate ( quantity of activity/ time) ER = Emission reduction efficiency

    2. EPA Emission Factors Example : Emissions From Bituminous Coal Combustion Obtain Activity Rate: Coal Flow rate in this case

    3. Visibility and Particulates in Air Depends on the nature and concentration of particulates Gas phase reactions ---> particles ---> effects visibility Haze in Los Angeles, Denver Smog in Baton Rouge Without particles visibility generally should of the order of 150 miles With no circulation particles remain suspended in air Smaller particles remain suspended longer

    4. Visibility and Particulates in Air Loss of Intensity through pathlength, d Magnitude of loss characterized by ?ext (extinction coefficient) depends on the amount of scattering or absorption depends on the composition and size, optical properties Typically I = I0 . exp (-?ext d) or ln (I/I0) = - ?ext d

    5. Visibility and Particulates in Air Extinction Coefficient, ?ext Rayleigh Scattering Scattering of gases by air molecules Absorption by Gases Some gases reflect certain wavelength of light (color) Absorption by Particles Typically carbon/soot particles Scattering by Particles Mie Scattering ?ext = ?Rayleigh + ?abs-gas + ?abs-part + ?scat-part Expressed as km-1

    6. Visibility and Particulates in Air Limit of Visibility, LV Defined as the limit when I = 0.02.I0 (2 percent) ln (I/I0) = - ?ext d ln (0.02) = - ?ext LV LV = 3.9 / ?ext If ?ext is known, the limit of visibility can be calculated. ?Rayleigh is a function of wavelength. ?scat-part = NK? r2 (for homogenous particles) K – scattering area ratio For scattering only, C : concentration of particles ?p : particle density r : particle radius

    7. Fate and Transport of Pollutants in Air Elementary reactions and Complex reactions. Examples of OZONE and SMOG We saw in the last class the number of hazardous effects of emissions. So one of the things we are concerned about now is fate and transport of chemicals that are released into the air. What do we mean by fate? Whether it will remain as it is or it will decay? What are the consequences of its reactivity? How do we assess the reactivity of a chemical? Question . Lead to the aspect of rate and rate expression and the reaction rate constant? We saw in the last class the number of hazardous effects of emissions. So one of the things we are concerned about now is fate and transport of chemicals that are released into the air. What do we mean by fate? Whether it will remain as it is or it will decay? What are the consequences of its reactivity? How do we assess the reactivity of a chemical? Question . Lead to the aspect of rate and rate expression and the reaction rate constant?

    8. Fate and Transport of Pollutants in Air Elementary reactions and Complex reactions. Examples of OZONE and SMOG We saw in the last class the number of hazardous effects of emissions. So one of the things we are concerned about now is fate and transport of chemicals that are released into the air. What do we mean by fate? Whether it will remain as it is or it will decay? What are the consequences of its reactivity? How do we assess the reactivity of a chemical? Question . Lead to the aspect of rate and rate expression and the reaction rate constant? We saw in the last class the number of hazardous effects of emissions. So one of the things we are concerned about now is fate and transport of chemicals that are released into the air. What do we mean by fate? Whether it will remain as it is or it will decay? What are the consequences of its reactivity? How do we assess the reactivity of a chemical? Question . Lead to the aspect of rate and rate expression and the reaction rate constant?

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