Comparison of emissions from steam- and water-assisted lab-scale flames

•“Assisted” flares are commonly used in the oil and gas industry to reduce black carbon emissions.•An emission comparison study of water- and steam-assist on turbulent non-premixed flames was carried out.•Liquid water reduced black carbon and NOx emissions more than steam for an equivalent mass of assist fluid.•The enhanced reduction in emissions when using liquid water was most likely due to thermal effects.