Characteristics and environmental impact of VOCs and greenhouse gas emissions from ground flares of typical petrochemical enterprises

In response to the severe situation of pollution and carbon reduction in China's petrochemical industry, two ground flares in a petrochemical company with millions of tons of ethylene cracking capacity were studied. Through on-site sampling monitoring and model calculation, the emission characteristics of volatile organic compounds (VOCs) and greenhouse gases from the flares during the combustion process were systematically explored. The results showed that VOCs emissions from Flare A and B in 2021 were 310.56 and 77.38 t/a, respectively, with olefins as the main emitted components. Greenhouse gas emissions were dominated by CO₂ generated from the conversion of carbon-containing compounds into combustion, accounting for about 99.98% of the total CO₂ emissions from flares. The ozone formation potential (OFP) of Flare A and B was 3 011.72 and 628.97 t/a, respectively, and ethylene and propylene were the main contributors to OFP of Flare A and B, with contribution rate of 39.52% and 44.91%, respectively. The global warming potential (GWP) of the two flares was 5 806.92 and 1 148.46 t/a CO₂eq, respectively, with CO₂ contributing the most, leading to a direct greenhouse effect which was 25.12-35.46 times that of CH₄, and 6.64-7.24 times that of the greenhouse effect indirectly caused by VOCs emissions.