Impacts of Air-Assist Flare Blower Configurations on Flaring Emissions

Air-assisted flares, operating under low flow conditions (<1% of maximum flow) with low BTU gases, have relatively narrow bands of air-to-vent gas ratios that can achieve destruction and removal efficiencies (DREs, fraction of waste gases destroyed by complete and incomplete combustion) greater than 98%. If blower configurations are not able to operate within these narrow bands, emissions may be greater than those predicted based on 98% DRE, but if air-assist rates can be finely tuned, emissions much lower than those predicted assuming 98% DRE are achievable. This work examines the potential impact on emissions of using four different blower configurations (single fixed speed, dual fixed speed, single variable speed, and dual variable speed) on an air-assisted flare. Typical patterns of flare vent gas flow rates were obtained from hourly data on flared gas flow rates from Houston, Texas. The analyses indicate that flare emissions can be much greater (up to a factor of 40) than a base case assuming 98% DRE...