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SO 2 Emission Factors. Kristin Burford 23/April/01 ME 449A: Sustainable Air Quality. Source: Environmental News Service. Table of Contents. Purpose and Methods EPA Emission Preparation Major Sources of SO 2 Coal Combustion Oil Combustion Gas Combustion Petroleum Refining
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SO2 Emission Factors Kristin Burford 23/April/01 ME 449A: Sustainable Air Quality Source: Environmental News Service
Table of Contents • Purpose and Methods • EPA Emission Preparation • Major Sources of SO2 • Coal Combustion • Oil Combustion • Gas Combustion • Petroleum Refining • Non-Road Diesel • Trends of SO2 Emissions • Summary and Recommendations
Purpose and Methods • Determine how the SO2 emissions were calculated by the EPA • Find out general emission calculation information • Determine major sources of SO2 according to 1996 Trends Data • Explore the specific factors which influence the the SO2 emissions for the major sources
EPA Emission Preparation • How are emissions determined? • Two factors: source information and emission factors General Equation: Emission = Emission Factor*Quality of Consumed Fuel • emission factors found in AP-42 • qualities of consumed fuel include amount of fuel, energy produced, % of precursor element in the fuel • In this study, the focus is on emission factors and how they are calculated • EPA rates the emission factors from A (best) to E according to how well the calculated emission correlates with the actual emission
Major Sources of SO2 (1996) • The major sources of SO2 emissions include: • Fuel Combustion • Coal • Oil • Gas • Industrial Processes • Petroleum Refining • Transportation • Non-Road Diesel • For more detailed information on the SO2 sources, consult EPA SO2 trends data for 1996
Coal Combustion Emission Factors • 60-70% of SO2 Emissions • Coal Rank: • anthracite - more C, less volatile, rare • bituminous - less C & more volatile than anthracite, most common • sub-bituminous - lower S, more volatile & moisture than bituminous • Uncontrolled emission factors (lbs SO2/ton coal): • 38*%S - bituminous Rating: A • 35*%S - sub-bituminous Rating: A • 39*%S - anthracite Rating: B • Have shown good correlation between calculated and actual emissions
Oil Combustion • 10-20% of total SO2 emissions • Uncontrolled emission factor (lbs SO2/103 gal): 0.98(MWSO2/MWS)(%S/100)x oil density x 1000 (oil gallons) Rating: A • Variables and Assumptions: • 98% conversion assumed • %S • MW • oil density • assumed 7 for distillate and 8 for residual • actual range 6.97- 7.03 (distillate) 7.95-8.17 (residual)
Gas Combustion • 5-10% of total SO2 emissions • Uncontrolled emission factor: (S grains/100 ft3)(lb/7000 grains)(ft3/1000 gal)(2 lb SO2/lb S) = 0.6 lbs SO2/106 std. ft3 (scft) gas Rating: A • Assumes 100% conversion of fuel S to SO2 and 2000 grains of S/106 scft. • Can convert emission factor to energy units using the average heating value of the gas (good approximation?) • Actual emissions not measured, therefore accuracy of emission factor is difficult to determine • Conservative, assume all S --> SO2
Petroleum Refining • 1-5% of total SO2 emissions • No background on emission factor calculation in AP-42 • Refining includes converting crude oil to over 2500 different products • Multiple Processes • Separation • Conversion • Treating • Feedstock and product handling • Auxiliary processes • The emission factors in the AP-42 have large ranges, probably depending on the product purity desired
Non-Road Diesel • 1-5% of total SO2 emissions • Data indicates that non-road diesel has a much larger contribution than any other transportation source • Not included in AP-42 online • EPA has limited information on emissions of non-road sources • Emissions based on : travel & rate of emission • SO2 based on 0.25% S in fuel (can be adjusted) • EPA recently decided to reduce the amount of sulfur in diesel fuels, however this will only effect road sources (see Federal Register for more information)
Trends of SO2 Emissions • Total SO2 emission & Coal SO2 emission have virtually the same trend • Other sources did not have a great impact on the total SO2 emissions (see other trend plots)
Summary and Recommendations • Summary: • Generally, the emission factors for combustion are accurate. • Petroleum refining and non-road diesel sources emission factors are not clearly defined • Recommendations: • Further work should be done on controls for the combustion sources • Improve accuracy of emission factors for other sources which significantly contribute to total SO2 emissions • Consider regulating sulfur in non-road diesel fuels