Estimation of Emission Factors for Sour Gas Flares

Gas flares are extensively used to control waste gases in oil and gas processing plants. Practically, flaring results in unregulated release of SO2, H2S and various hydrocarbons and particulates, which are harmful to human and environmental health. In this work, a back–calculation method was used to estimate SO2, CO and NO2 emission factors for a typical petroleum sour gas flare. The mean emission factors were estimated as 0.96, 0.97 and 0.020 lb/MMBtu (pound per Million British thermal unit) (0.41, 0.42 and 0.0086 kg/109J) for CO, SO2 and NO2 in an Iranian sour gas flare, respectively. The results showed that, estimated CO emission factor was in a good agreement with reported ARPEL (Regional Association of Oil and Natural Gas Companies in Latin America and the Caribbean) emission factor. However, for SO2 emission factor, fuel analysis method showed 87% difference from SO2 estimated emission factor. In addition, the results indicated that for the selected gas flare, NO2 emission factor is much lower than published emission factors. The uncertainty analysis showed that due to high uncertainty of dispersion model, the total uncertainty could be higher than 50% for all emission factors.