The Estimation of CO₂ Emission Factors for Combustion Sources in Oil and Gas Processing Plants

Abstract

CO₂ emission factors developed from fuel-specific data are more reliable than published average emission factors. In this article, CO₂ emission factors were estimated for main combustion sources including gas turbines, boilers, and gas flares in an Iranian oil and gas processing plant using a fuel analysis method as well as direct measurements. In general, the emission factors for gas flares were higher than gas turbines and boilers. However, it is believed that CO₂ emission factors are not very sensitive to combustion devices. CO₂ emission factors varied significantly with the quality of fuels and operation conditions. The mean CO₂ emission factor for a gas turbine was calculated as 114.47 lb/MMBtu (pound per million British thermal unit). This emission factor has good agreement with EPA and CAPP data. However, for the considered boiler due to poor fuel quality, an unexpected high mean value emission factor of 171.57 lb/MMBtu with uncertainty of 23.84% was obtained. The mean emission factor for gas flares was calculated as 122.15 lb/MMBtu and 112.18 lb/MMBtu with less than 1.5% uncertainty for combustion efficiency values of 98% and 90%, respectively. The results showed that among gas flares, the acid gas flares' CO₂ emission factors are high and strongly dependent to gas composition and heating value.

Keywords:

• CO₂
• emission factor
• flare
• oil and gas processing

Notes

^a Btu/scf: British thermal unit per standard cubic feet.