Testing Flare Emission Factors for Flaring in Refineries

The Technical University of Madrid (UPM) and REPSOL YPF are collaborating in the improvement in the estimation of the emiss ion factors for refinery flares. Flaring is an unavoidable process in the refining activity, both for safety reasons during upset processes (start-up, shut down, system blow-down) and when managing the disposal of waste gases with hydrocarbon from routine operations. The official flare gas emissions in Spain are currently evaluated using the CORINAIR methodology (SNAP 090203) and surveys from the petrol companies. However, the emission factors used in CORINAIR could be non-representative for some plants in Spain. Therefore, the aim of this study is to improve the value of the above mentioned emission factors in order to transform them into more accurate ones. The study compares the factors included in the references with factors obtained directly from flare measures and gas analyses in oil refineries. In this case, the emission sources selected are four flares belonging to two REPSOL YPF refineries. Three of the flares considered are located at the same refinery and the fourth one is selected from another refinery in order to compare the results. This refinery has just one flare. Several studies from other companies and institutions (US EPA, BP, OLF, Shell) are taken into account. These studies are focused on the measure of combustion efficiency, which is the indicator of a complete combustion. Different estimations of emissions have been carried out considering different combustion efficiencies. The pollutants considered are Carbon Dioxide (CO2) and Methane (CH4).