NOx Emission Factors

Robert Fowler

ME 449: Sustainable Air Quality

April 2001

Table of Contents

• Objective of work

• Major contributors for NOx emissions

• Emission factor equations

• Data sources

• Summary

• Recommendations

Objective

• Show emission factor calculations

MethodWeb search and EPA manual foe emission factors AP-42

Major Contributors to NOx

• Transportation - gas and diesel vehicles

• Fuel combustion - power plants

• Industrial Processes - waste disposal/petroleum refinery

Nox EmissionsFuel

Combustion41%

Industrial Processes

7%

Transportation52%

Transportation emission equation

Driving factors: Emission factor and vehicle miles traveled

Equation for emission factor

EF = (BER*OMTCF+OMTTAM)*SALCHF*TF

• BER - basic emission rate

• OMTCF - operating mode/temperature correction factor

• OMTTAM - Tampering offset

• SALCHF - Speed correction factor

• TF - Travel fraction

To get the emission inventory:

EI = EF * VMT

Fuel combustion emission equation

Driving factors: emission factor & quantity of fuel consumed

Emission factor: Mass of pollutant/mass of fuel (or output)

•Boilers - lb NOx/ton fuel

•ICE’s - lb NOx/hp-hr power output and lb NOx/MMBtu fuel input

•Gas turbines - lb NOx/MMBtu fuel

•Stationary diesels - lb NOx/hp-hr power output and lb NOx/MMBtu fuel input

•Stationary dual fuel engines - lb NOx/hp-hr power output and lb NOx/MMBtu fuel input

Industrial Processes emission equations

Driving factors: Emission factor and mass of fuel burned

Emission factor: mass pollutant/mass (or volume) fuel

• Solid waste disposal - kg NOx/Mg refuse or lb NOx/ton refuse

• Sewage sludge - kg NOx/Mg refuse or lb NOx/ton sludge

• Medical - kg NOx/Mg refuse or lb NOx/ton refuse

• Open burning - kg NOx/Mg refuse or lb NOx/ton refuse

• Auto Body - kg NOx/Mg refuse or lb NOx/ton refuse

• Evaporation losses - g/drum or lb/drum

• Petroleum refineries - kg NOx/103 L fresh feed; lb NOx/1000 bbl (barrel) fresh feed; kg NOx/1000

m3 gas burned; lb NOx/1000 ft3 gas burned; kg NOx/103 L refinery feed; lb NOx/1000 bbl refinery feed

Data Source

• Transportation data - EPA AP-42 Vol II Appendix G

http://www.epa.gov/otaq/ap42.htm

• Fuel combustion and industrial processes - EPA AP-42 Vol I Chapter 1-5, 11

http://www.epa.gov/ttn/chief/ap42/ch01/

http://www.epa.gov/ttn/chief/ap42/ch02/

http://www.epa.gov/ttn/chief/ap42/ch03/

http://www.epa.gov/ttn/chief/ap42/ch04/

http://www.epa.gov/ttn/chief/ap42/ch05/

http://www.epa.gov/ttn/chief/ap42/ch11/

Summary

• The major contributors of NOx emissions are transportation, fuel combustion, and industrial processes

• Emission inventory is determined by the emission factor times the driving force

• Data came from EPA AP-42 manual Vol I & II

Conclusion• Still don’t know what the equations are to determine the numbers for

the emission factors

• EPA website very useful obtaining the emission factor for whatever fuel you need it for

Recommendations for improving emission factors• The uncontrolled emission factors can be reduced by better controls

within the system prior to exhaust

• The controlled emission factors can be reduced by better scrubbers and filters at the exhaust